feat(编辑渲染): 完善三维转换，优化编辑渲染压缩

ofdgo_backend.go

@@ -43,6 +43,14 @@ type RasterBackend interface {
 	Render(*RasterPage) (image.Image, error)
 }
 
+// RasterBufferBackend 可选的目标缓冲绘制能力，不改变后端和采样精度
+// 目标须为原点为零、尺寸与页面一致的紧密RGBA缓冲，不得与输入图像共享数据
+// 绘制前清空目标像素，不保留目标引用；失败时目标可能包含部分结果
+type RasterBufferBackend interface {
+	RasterBackend
+	RenderInto(*RasterPage, *image.RGBA) error
+}
+
 // PageCompiler 统一页面编译、文字提取和对象度量，不得修改源数据
 // 三项能力需采用相同的字体和几何语义，避免绘制、搜索与选区不一致
 // renderer提供文档、字体配置和文字回调，实现中不得递归调用对应的Renderer方法

ofdgo_compression.go

@@ -164,6 +164,9 @@ func (e *Editor) outputSnapshot(ctx context.Context, options WriteOptions) (*Edi
 			return nil, err
 		}
 	}
+	if err := snapshot.compressPatternPaints(); err != nil {
+		return nil, err
+	}
 	return &snapshot, nil
 }
 

ofdgo_compression_pattern.go

@@ -0,0 +1,164 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"crypto/sha256"
+	"reflect"
+	"slices"
+)
+
+const (
+	compressionPatternMinimum = 4096
+	compressionPatternLimit   = 4096
+	compressionPatternUses    = 65536
+)
+
+// compressionPatternPaint 保存可共享的底纹颜色，不修改输入对象
+type compressionPatternPaint struct {
+	fill   *FillColor
+	stroke *StrokeColor
+	count  int
+	id     string
+}
+
+// compressionPatternUse 记录输出快照内需要替换的直接对象
+type compressionPatternUse struct {
+	page, layer, object int
+	paint               *compressionPatternPaint
+}
+
+// compressPatternPaints 将新文档中重复的大底纹颜色提取为绘制参数，仅修改输出快照
+// 返回: error 编码或取消错误
+func (e *Editor) compressPatternPaints() error {
+	if e.output == nil || e.output.options.Mode == CompressionUnchanged || e.output.protected || e.source != nil {
+		return nil
+	}
+	paints := make(map[[32]byte]*compressionPatternPaint)
+	var uses []compressionPatternUse
+	for pi, page := range e.pages {
+		for li, layer := range page.Content.Layer {
+			if layer.DrawParam != "" {
+				continue
+			}
+			for oi, object := range layer.Objects {
+				if err := e.output.ctx.Err(); err != nil {
+					return err
+				}
+				if len(uses) == compressionPatternUses {
+					break
+				}
+				fill, stroke := compressionObjectPattern(object)
+				if fill == nil && stroke == nil {
+					continue
+				}
+				hash := sha256.New()
+				var size int64
+				x := newOFDXML(convertWriter{writer: hash, count: &size, context: e.output.ctx})
+				x.ctx = e.output.ctx
+				x.color("FillColor", fill)
+				x.color("StrokeColor", (*FillColor)(stroke))
+				if err := x.finish(); err != nil {
+					return err
+				}
+				if size < compressionPatternMinimum {
+					continue
+				}
+				key := [32]byte(hash.Sum(nil))
+				paint := paints[key]
+				if paint == nil {
+					if len(paints) == compressionPatternLimit {
+						continue
+					}
+					paint = &compressionPatternPaint{fill: fill, stroke: stroke}
+					paints[key] = paint
+				} else if !reflect.DeepEqual(paint.fill, fill) || !reflect.DeepEqual(paint.stroke, stroke) {
+					continue
+				}
+				paint.count++
+				uses = append(uses, compressionPatternUse{pi, li, oi, paint})
+			}
+		}
+	}
+	var copied bool
+	lastPage, lastLayer := -1, -1
+	for _, use := range uses {
+		if err := e.output.ctx.Err(); err != nil {
+			return err
+		}
+		if use.paint.count < 2 {
+			continue
+		}
+		if !copied {
+			e.pages = slices.Clone(e.pages)
+			e.resources = slices.Clone(e.resources)
+			copied = true
+		}
+		if use.paint.id == "" {
+			id, err := e.addEditorDrawParam(DrawParam{FillColor: use.paint.fill, StrokeColor: use.paint.stroke})
+			if err != nil {
+				return err
+			}
+			use.paint.id = id
+		}
+		if use.page != lastPage {
+			e.pages[use.page].Content.Layer = slices.Clone(e.pages[use.page].Content.Layer)
+			lastPage, lastLayer = use.page, -1
+		}
+		layer := &e.pages[use.page].Content.Layer[use.layer]
+		if use.layer != lastLayer {
+			layer.Objects = slices.Clone(layer.Objects)
+			lastLayer = use.layer
+		}
+		object := &layer.Objects[use.object]
+		if object.Type == "PathObject" {
+			object.PathObject.DrawParam = use.paint.id
+			object.PathObject.FillColor, object.PathObject.StrokeColor = nil, nil
+		} else {
+			object.TextObject.DrawParam = use.paint.id
+			object.TextObject.FillColor, object.TextObject.StrokeColor = nil, nil
+		}
+	}
+	return nil
+}
+
+// compressionObjectPattern 筛选没有原文及绘制参数继承的底纹对象
+// 入参: object 图形对象
+// 返回: *FillColor 填充颜色, *StrokeColor 描边颜色，不适用时均为空
+func compressionObjectPattern(object GraphicObject) (*FillColor, *StrokeColor) {
+	if object.origin != nil {
+		return nil, nil
+	}
+	var fill *FillColor
+	var stroke *StrokeColor
+	switch object.Type {
+	case "PathObject":
+		if object.PathObject.DrawParam != "" {
+			return nil, nil
+		}
+		fill, stroke = object.PathObject.FillColor, object.PathObject.StrokeColor
+	case "TextObject":
+		if object.TextObject.DrawParam != "" {
+			return nil, nil
+		}
+		fill, stroke = object.TextObject.FillColor, object.TextObject.StrokeColor
+	default:
+		return nil, nil
+	}
+	if fill != nil && fill.Pattern != nil || stroke != nil && stroke.Pattern != nil {
+		return fill, stroke
+	}
+	return nil, nil
+}

ofdgo_compression_resources.go

@@ -50,6 +50,7 @@ func (e *Editor) compressResourceReferences(parts map[string][]byte, reader *Rea
 	if e.output == nil || e.output.options.Mode == CompressionUnchanged || e.output.protected {
 		return nil
 	}
+	generated = e.generatedVectorReferences(parts, generated)
 	names := make(map[string]bool)
 	if reader != nil {
 		for name := range reader.fileIndex {

ofdgo_editor.go

@@ -84,6 +84,7 @@ type editorResource struct {
 	vectorKey    [32]byte
 	vectorStates map[string]editorCompositeState
 	references   []string
+	usage        *editorVectorUsage
 	subset       *editorFontSubset
 	states       map[string]editorCompositeState
 	draw         *DrawParam

ofdgo_editor_batch.go

@@ -170,6 +170,14 @@ func (e *Editor) CopyObjectsContext(ctx context.Context, page int, objects []Gra
 // 入参: ctx 取消上下文, page 目标页, objects 无原文和标识且调用方不再修改的对象
 // 返回: error 校验或取消错误，失败时不提交页面内容
 func (e *Editor) appendOwnedObjects(ctx context.Context, page int, objects []GraphicObject) error {
+	return (&editorValidation{Editor: e}).appendOwnedObjects(ctx, page, objects)
+}
+
+// appendOwnedObjects 在资源不变的构建会话内复用校验结果，接收对象所有权
+// 入参: ctx 取消上下文, page 目标页, objects 无原文和标识的独立对象
+// 返回: error 校验或取消错误
+func (v *editorValidation) appendOwnedObjects(ctx context.Context, page int, objects []GraphicObject) error {
+	e := v.Editor
 	if err := ctx.Err(); err != nil {
 		return err
 	}
@@ -182,7 +190,6 @@ func (e *Editor) appendOwnedObjects(ctx context.Context, page int, objects []Gra
 	if err := e.prepareSourceIDs(); err != nil {
 		return err
 	}
-	validation := &editorValidation{Editor: e}
 	for i, object := range objects {
 		if err := ctx.Err(); err != nil {
 			return err
@@ -190,7 +197,7 @@ func (e *Editor) appendOwnedObjects(ctx context.Context, page int, objects []Gra
 		if object.origin != nil || editorObjectID(object) != "" {
 			return fmt.Errorf("owned objects must not have identifiers or original content")
 		}
-		prepared, err := validation.prepareObject("", object)
+		prepared, err := v.prepareObject("", object)
 		if err != nil {
 			return err
 		}

ofdgo_editor_color.go

@@ -39,7 +39,7 @@ type editorValidation struct {
 	*Editor
 	patterns   map[*Pattern]bool
 	composites map[string]bool
-	vectors    map[string]*editorCompositeNode
+	vectors    map[string]bool
 	paths      map[string]bool
 }
 
@@ -142,7 +142,7 @@ func (e *Editor) StylePatterns(page int, ids []string, stroke bool, style Patter
 			return err
 		}
 	}
-	objects, _, err := e.selectedObjects(page, ids)
+	objects, indexes, err := e.selectedObjects(page, ids)
 	if err != nil {
 		return err
 	}
@@ -150,17 +150,51 @@ func (e *Editor) StylePatterns(page int, ids []string, stroke bool, style Patter
 		objects[i] = cloneEditorData(objects[i])
 		object := &objects[i]
 		var fill *FillColor
+		var draw string
 		switch object.Type {
 		case "TextObject":
+			draw = object.TextObject.DrawParam
 			fill = object.TextObject.FillColor
 			if stroke {
 				fill = (*FillColor)(object.TextObject.StrokeColor)
 			}
 		case "PathObject", "Path":
+			draw = object.PathObject.DrawParam
 			fill = object.PathObject.FillColor
 			if stroke {
 				fill = (*FillColor)(object.PathObject.StrokeColor)
 			}
+		default:
+			return fmt.Errorf("object %q does not use a pattern", ids[i])
+		}
+		if fill == nil {
+			base, err := e.editorDrawParam(e.pages[page].Content.Layer[indexes[i].layer].DrawParam, make(map[string]bool))
+			if err != nil {
+				return err
+			}
+			param, err := e.editorDrawParam(draw, make(map[string]bool))
+			if err != nil {
+				return err
+			}
+			paint := mergeDrawParam(*base, param)
+			fill = paint.FillColor
+			if stroke {
+				fill = (*FillColor)(paint.StrokeColor)
+			}
+			fill = cloneEditorData(fill)
+			if object.Type == "TextObject" {
+				if stroke {
+					object.TextObject.StrokeColor = (*StrokeColor)(fill)
+				} else {
+					object.TextObject.FillColor = fill
+				}
+			} else if object.Type == "PathObject" || object.Type == "Path" {
+				if stroke {
+					object.PathObject.StrokeColor = (*StrokeColor)(fill)
+				} else {
+					object.PathObject.FillColor = fill
+				}
+			}
 		}
 		if fill == nil || fill.Pattern == nil {
 			return fmt.Errorf("object %q does not use a pattern", ids[i])

ofdgo_editor_composite.go

@@ -1097,21 +1097,18 @@ func (v *editorValidation) validateVector(id string) error {
 	if v.composites[id] {
 		return fmt.Errorf("cyclic composite resource %q", id)
 	}
+	if v.vectors[id] {
+		return nil
+	}
 	if v.composites == nil {
 		v.composites = make(map[string]bool)
-		v.vectors = make(map[string]*editorCompositeNode)
 	}
 	v.composites[id] = true
 	defer delete(v.composites, id)
-	node := v.vectors[id]
+	node, err := v.compositeDefinition(id)
-	if node == nil {
-		var err error
-		node, err = v.compositeDefinition(id)
 	if err != nil {
 		return err
 	}
-		v.vectors[id] = node
-	}
 	unit := node.object.CompositeGraphicUnit
 	if node.node.attr("Width") == "" || node.node.attr("Height") == "" || !finite(unit.Width) || !finite(unit.Height) || unit.Width < 0 || unit.Height < 0 {
 		return fmt.Errorf("invalid vector dimensions")
@@ -1131,5 +1128,9 @@ func (v *editorValidation) validateVector(id string) error {
 			return err
 		}
 	}
+	if v.vectors == nil {
+		v.vectors = make(map[string]bool)
+	}
+	v.vectors[id] = true
 	return nil
 }

ofdgo_editor_composite_insert.go

@@ -249,7 +249,7 @@ func (e *Editor) addEditorDrawParam(draw DrawParam) (string, error) {
 		return "", err
 	}
 	draw.ID = e.nextID()
-	data, err := encodeOFDXML(func(x *ofdXML) {
+	data, err := e.encodeXML(func(x *ofdXML) {
 		x.root("Res", ofdAttrs{{Name: xml.Name{Local: "BaseLoc"}, Value: "."}})
 		x.start("DrawParams", nil)
 		attrs := ofdAttrs{}

ofdgo_editor_font.go

@@ -202,13 +202,16 @@ func (e *Editor) subsetFonts(progress editorProgress) (map[string][]byte, error)
 				if object.Type == "CompositeObject" || object.Type == "CompositeGraphicUnit" {
 					composite = true
 					origin := e.objectOrigin(editorObjectID(object))
+					var data []byte
+					var err error
 					if origin == nil {
-						return nil, nil
+						data, err = e.encodeXML(func(x *ofdXML) { x.object(object, true) })
-					}
+					} else {
-					data, err := editorXMLObject(origin.data, origin.node, origin.object, object)
+						data, err = editorXMLObject(origin.data, origin.node, origin.object, object)
 						if err == nil {
 							data, err = editorXMLStandalone(data, origin.node)
 						}
+					}
 					if err != nil {
 						return nil, err
 					}
@@ -252,18 +255,30 @@ func (e *Editor) subsetFonts(progress editorProgress) (map[string][]byte, error)
 			if err := progress.report("fonts", len(e.pages)+i, total); err != nil {
 				return nil, err
 			}
-			if _, safe := refs.scan(bytes.NewReader(resource.data), resource.name); !safe {
+			if resource.usage.matches(resource.name, resource.data) {
+				refs.merge(resource.usage.refs)
+			} else if _, safe := refs.scan(bytes.NewReader(resource.data), resource.name); !safe {
 				return nil, nil
 			}
 		}
 		for id, usage := range refs.fonts {
 			glyphs := used[id]
-			if usage.unsafe || len(usage.glyphs) != 0 {
+			if usage.unsafe {
 				delete(used, id)
 			} else if glyphs != nil {
 				for char := range usage.chars {
 					glyphs[e.fonts[id].GlyphIndex(char)] = true
 				}
+				if len(usage.glyphs) != 0 {
+					mapped[id] = true
+					for glyph := range usage.glyphs {
+						if glyph >= e.fonts[id].NumGlyphs() {
+							delete(used, id)
+							break
+						}
+						glyphs[glyph] = true
+					}
+				}
 			}
 		}
 	}

ofdgo_editor_reference.go

@@ -16,13 +16,17 @@ package ofdgo
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"encoding/xml"
 	"maps"
 	"strings"
 	"unicode/utf8"
 )
 
-// editorGeneratedReferences 保存本次编码页面及其引用，不跨写出复用
+// editorVectorUsageLimit 限制单个矢量引用快照的记录数，不限制资源内容
+const editorVectorUsageLimit = 4096
+
+// editorGeneratedReferences 保存本次输出条目及其引用，不跨写出复用
 type editorGeneratedReferences struct {
 	data   []byte
 	refs   *editorResourceRefs
@@ -39,9 +43,49 @@ func (r editorGeneratedReferences) matches(data []byte) bool {
 	return bytes.Equal(data, r.data)
 }
 
+// editorVectorUsage 保存自产矢量资源的引用快照，内容和路径变化时失效
+type editorVectorUsage struct {
+	name   string
+	digest [32]byte
+	refs   *editorResourceRefs
+}
+
+// matches 核对资源路径和完整内容摘要，不以切片地址判断内容
+// 入参: name 当前资源路径, data 当前资源内容
+// 返回: bool 是否仍可使用编码时的引用
+func (u *editorVectorUsage) matches(name string, data []byte) bool {
+	return u != nil && u.name == name && u.digest == sha256.Sum256(data)
+}
+
+// generatedVectorReferences 合并未改变的自产矢量引用，不修改调用方集合
+// 入参: parts 输出条目, generated 本次已知引用
+// 返回: map[string]editorGeneratedReferences 本次可复用引用
+func (e *Editor) generatedVectorReferences(parts map[string][]byte, generated map[string]editorGeneratedReferences) map[string]editorGeneratedReferences {
+	copied := false
+	for _, resource := range e.resources {
+		if e.output != nil && e.output.ctx.Err() != nil {
+			return generated
+		}
+		data, ok := parts[resource.name]
+		if !ok || !resource.usage.matches(resource.name, data) {
+			continue
+		}
+		if !copied {
+			generated = maps.Clone(generated)
+			if generated == nil {
+				generated = make(map[string]editorGeneratedReferences)
+			}
+			copied = true
+		}
+		generated[resource.name] = editorGeneratedReferences{data: data, refs: resource.usage.refs}
+	}
+	return generated
+}
+
 // editorReferenceScan 按XML事件收集资源和字体用字，未知内容保持完整扫描
 type editorReferenceScan struct {
 	refs     *editorResourceRefs
+	objects  map[string]bool
 	name     string
 	base     string
 	stack    []string
@@ -53,6 +97,26 @@ type editorReferenceScan struct {
 	seen     bool
 }
 
+// vectorUsage 保留完整且限额内的自产矢量引用，超限时保存流程重新扫描
+// 入参: data 本次编码内容
+// 返回: *editorVectorUsage 引用快照，无法复用时为空
+func (s *editorReferenceScan) vectorUsage(data []byte) *editorVectorUsage {
+	if !s.safe || !s.seen || len(s.stack) != 0 {
+		return nil
+	}
+	count := len(s.refs.ids) + len(s.refs.files) + len(s.refs.fonts)
+	for _, usage := range s.refs.fonts {
+		count += len(usage.chars) + len(usage.glyphs)
+		if count > editorVectorUsageLimit {
+			return nil
+		}
+	}
+	if count > editorVectorUsageLimit {
+		return nil
+	}
+	return &editorVectorUsage{name: s.name, digest: sha256.Sum256(data), refs: s.refs}
+}
+
 // accept 共用读取和自产页面的引用判断，不将对象自身标识视为引用
 // 入参: token 已解析或已编码的XML事件
 // 返回: bool 是否仍可完整判断引用
@@ -99,6 +163,9 @@ func (s *editorReferenceScan) accept(token xml.Token) bool {
 			if attr.Name.Local != "ID" {
 				s.refs.reference(s.name, s.base, attr.Name.Local, attr.Value, s.resource)
 			}
+			if s.objects != nil && editorObjectReference(attr.Name.Local) {
+				s.objects[attr.Value] = true
+			}
 			if attr.Name.Local == "Font" {
 				usage = s.refs.fontUsage(attr.Value)
 				if token.Name.Local != "TextObject" && token.Name.Local != "Text" {
@@ -122,6 +189,11 @@ func (s *editorReferenceScan) accept(token xml.Token) bool {
 			return false
 		}
 		s.refs.reference(s.name, s.base, token.Name.Local, s.text.String(), s.resource)
+		if s.objects != nil && (token.Name.Local == "Thumbnail" || token.Name.Local == "Substitution") {
+			if id := editorResourceID(s.text.String()); id != "" {
+				s.objects[id] = true
+			}
+		}
 		if (token.Name.Local == "Substitution" || token.Name.Local == "Font") && strings.TrimSpace(s.text.String()) != "" {
 			s.refs.fontUsage(s.text.String()).unsafe = true
 		}

ofdgo_editor_resources.go

@@ -60,6 +60,7 @@ func (e *Editor) compactSourceReferences(parts map[string][]byte, progress edito
 	if len(parts) == 0 && e.revision == 0 && (e.output == nil || e.output.options.Mode == CompressionUnchanged) {
 		return nil, nil
 	}
+	generated = e.generatedVectorReferences(parts, generated)
 	reader := e.source.reader
 	names := make(map[string]bool)
 	for name := range reader.fileIndex {

ofdgo_editor_style.go

@@ -91,7 +91,11 @@ func (e *Editor) ApplyAppearance(page int, ids []string, appearance ObjectAppear
 // 返回: *DrawParam 绘制参数, error 错误信息
 func (e *Editor) DrawParam(id string, resolved bool) (*DrawParam, error) {
 	if resolved {
-		return e.editorDrawParam(id, make(map[string]bool))
+		draw, err := e.editorDrawParam(id, make(map[string]bool))
+		if err != nil {
+			return nil, err
+		}
+		return cloneEditorData(draw), nil
 	}
 	for _, resource := range e.resources {
 		if resource.draw != nil && resource.draw.ID == id {

ofdgo_editor_vector.go

@@ -17,25 +17,41 @@ package ofdgo
 import (
 	"context"
 	"encoding/xml"
+	"fmt"
+	"maps"
+	"slices"
 )
 
 // addOwnedVector 将本库生成的独立对象注册为标准矢量资源，不保留内联复合内容
 // 入参: ctx 取消上下文, objects 无原文和标识的对象, width 资源宽度, height 资源高度
 // 返回: string 资源编号, error 校验、编码或取消错误
 func (e *Editor) addOwnedVector(ctx context.Context, objects []GraphicObject, width, height float64) (string, error) {
-	validation := &editorValidation{Editor: e}
+	return (&editorValidation{Editor: e}).addOwnedVector(ctx, objects, width, height)
+}
+
+// addOwnedVector 在资源不变的构建会话内登记矢量资源，复用资源校验结果
+// 入参: ctx 取消上下文, objects 无原文和标识的对象, width 资源宽度, height 资源高度
+// 返回: string 资源编号, error 校验、编码或取消错误
+func (v *editorValidation) addOwnedVector(ctx context.Context, objects []GraphicObject, width, height float64) (string, error) {
+	e := v.Editor
+	if !finite(width) || !finite(height) || width < 0 || height < 0 {
+		return "", fmt.Errorf("invalid vector dimensions")
+	}
 	for index, object := range objects {
 		if err := ctx.Err(); err != nil {
 			return "", err
 		}
-		prepared, err := validation.prepareObject(e.nextID(), object)
+		prepared, err := v.prepareObject(e.nextID(), object)
 		if err != nil {
 			return "", err
 		}
 		objects[index] = prepared
 	}
 	id := e.nextID()
+	name := e.packageName("Res/Composites/Composite_" + id + ".xml")
+	scan := &editorReferenceScan{refs: &editorResourceRefs{ids: make(map[string]bool), files: make(map[string]bool), fonts: make(map[string]*editorFontUsage)}, objects: make(map[string]bool), name: name, safe: true}
 	data, err := encodeOFDXMLContext(ctx, func(x *ofdXML) {
+		x.references = scan
 		x.root("Res", ofdAttrs{{Name: xml.Name{Local: "BaseLoc"}, Value: "."}})
 		x.start("CompositeGraphicUnits", nil)
 		x.start("CompositeGraphicUnit", ofdAttrs{{Name: xml.Name{Local: "ID"}, Value: id},
@@ -56,10 +72,20 @@ func (e *Editor) addOwnedVector(ctx context.Context, objects []GraphicObject, wi
 	if err != nil {
 		return "", err
 	}
-	resource, err := e.compositeResource(id, data)
+	resource := editorResource{name: name, data: data, composite: id}
+	if scan.safe && scan.seen && len(scan.stack) == 0 {
+		resource.references = slices.Sorted(maps.Keys(scan.objects))
+		resource.usage = scan.vectorUsage(data)
+	} else {
+		resource, err = e.compositeResource(id, data)
 		if err != nil {
 			return "", err
 		}
+	}
 	e.resources = append(e.resources, resource)
+	if v.vectors == nil {
+		v.vectors = make(map[string]bool)
+	}
+	v.vectors[id] = true
 	return id, ctx.Err()
 }

ofdgo_image.go

@@ -431,6 +431,17 @@ func imageNRGBAAt(img image.Image, x, y int) color.NRGBA {
 	return color.NRGBAModel.Convert(img.At(x, y)).(color.NRGBA)
 }
 
+// imageAlphaAt 读取十六位透明度，原生图像避免颜色装箱
+// 入参: img 图像, x 横坐标, y 纵坐标
+// 返回: uint32 十六位透明度
+func imageAlphaAt(img image.Image, x, y int) uint32 {
+	if source, ok := img.(image.RGBA64Image); ok {
+		return uint32(source.RGBA64At(x, y).A)
+	}
+	_, _, _, alpha := img.At(x, y).RGBA()
+	return alpha
+}
+
 // imageNRGBA64At 读取十六位非预乘像素，原生图像避免颜色装箱
 // 入参: img 图片对象, x X坐标, y Y坐标
 // 返回: color.NRGBA64 NRGBA64像素

ofdgo_pdf.go

@@ -32,7 +32,7 @@ var ErrPDFPassword = pdfgo.ErrPassword
 // Password默认使用PDF安全处理器编码，PasswordUTF8启用UTF-8输入及标准密码准备，空值尝试空密码
 // Strict禁止恢复缺失资源或丢失内容语义，默认在报告中记录警告
 // RendererOptions复用渲染器字体来源和后端配置，Backends优先于其中的后端设置
-// RasterDPI指定局部透明效果合成精度，0沿用渲染器DPI，默认300dpi，Strict禁用局部合成
+// RasterDPI指定局部合成与三维绘制精度，0沿用渲染器DPI，默认300dpi，Strict禁用局部合成
 // OnProgress按open、pages、convert及write.*阶段报告进度，total为0表示总量未知
 // ResolveFile读取PDF引用的外部媒体、附件和页面，默认不访问网络或本地路径
 // ResolveReference可提供已解密的引用页面，目标阅读器由调用方维护
@@ -86,12 +86,15 @@ type pdfImporter struct {
 	cmykSpace        string
 	iccSpaces        map[pdfICCKey]string
 	objects          *pdfObjectBuffer
+	formResources    *pdfFormCache
+	validation       *editorValidation
 	pages            map[pdfgo.Reference]*pdfgo.Page
 	pageIDs          map[pdfgo.Reference]string
 	pageIndexes      map[pdfgo.Reference]int
 	imageIDs         map[pdfImageKey][]pdfImageResource
 	imageContents    *renderCache[pdfImageContentKey, pdfImageContent]
 	attachmentIDs    map[pdfAttachmentKey]string
+	modelAttachments map[*pdfgo.Stream]string
 	maskClips        map[*pdfgo.SoftMask]pdfgo.Path
 	pageBox          pdfgo.Rectangle
 	pageWidth        float64
@@ -308,7 +311,7 @@ func (p *pdfImporter) commitObjects() error {
 	if err != nil {
 		return err
 	}
-	if err := p.editor.appendOwnedObjects(p.ctx, p.page, objects); err != nil {
+	if err := p.objectValidation().appendOwnedObjects(p.ctx, p.page, objects); err != nil {
 		return err
 	}
 	p.objects = nil
@@ -778,11 +781,7 @@ func (p *pdfImporter) buildTilingPattern(source *pdfgo.TilingPattern, base pdfgo
 		return nil, fmt.Errorf("invalid PDF tiling pattern raster scale")
 	}
 	cell.objects, cell.pendingPath = nil, nil
-	visitor := pdfgo.Visitor{Path: cell.path, Text: cell.text, Image: cell.image, Reference: p.referencePage}
+	if err := source.Walk(p.ctx, base, cell.visitor()); err != nil {
-	visitor.Group = func(mark pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
-		return cell.group(mark, walk, visitor)
-	}
-	if err := source.Walk(p.ctx, base, visitor); err != nil {
 		return nil, err
 	}
 	if err := cell.flushPath(); err != nil {

ofdgo_pdf_3d.go

@@ -0,0 +1,501 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"image"
+	"math"
+	"strings"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfModelAttachmentLimit 限制单次转换保留的共享模型索引数量
+const pdfModelAttachmentLimit = 1024
+
+// PDFThreeDRenderOptions 控制PDF三维视口的静态绘制，不改变注解激活状态
+// 缓存与实例上限为0时采用U3DRenderOptions的默认值
+type PDFThreeDRenderOptions struct {
+	Width, Height  int
+	MaxMemoryBytes int64
+	MaxInstances   int
+}
+
+// threeDAnnotation 按非交互呈现规则处理激活状态，保留原始模型与附件动作
+// 入参: ctx 取消上下文, page PDF页面, annotation 三维注解
+// 返回: error 外观、资源或取消错误
+func (p *pdfImporter) threeDAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation) error {
+	source, err := p.reader.ReadThreeD(annotation)
+	if err != nil {
+		return p.interactiveAppearanceFallback(ctx, page, annotation, "metadata", err)
+	}
+	var data []byte
+	id := p.modelAttachments[source.Stream]
+	if id == "" {
+		data, err = source.Stream.DecodeContext(ctx)
+		if err != nil {
+			return p.interactiveAppearanceFallback(ctx, page, annotation, "model", err)
+		}
+		id, err = p.editor.AddAttachment(fmt.Sprintf("Model_%d.%s", p.page+1, strings.ToLower(string(source.Format))), data)
+		if err != nil {
+			return err
+		}
+		if p.modelAttachments == nil {
+			p.modelAttachments = make(map[*pdfgo.Stream]string)
+		}
+		if len(p.modelAttachments) < pdfModelAttachmentLimit {
+			p.modelAttachments[source.Stream] = id
+		}
+	}
+	action := Action{Event: "CLICK", GotoA: &GotoA{AttachID: id}}
+	var paint func(*pdfImporter) error
+	if source.ActivationPolicy.Activation != "XA" {
+		appearance, err := p.reader.ReadAnnotationAppearance(annotation)
+		if err != nil {
+			return p.interactiveAppearanceFallback(ctx, page, annotation, "appearance", err)
+		}
+		if appearance == nil {
+			return fmt.Errorf("missing PDF 3D normal appearance")
+		}
+		if data == nil {
+			data, err = p.editor.source.reader.AttachmentData(id)
+			if err != nil {
+				return err
+			}
+		}
+		paint, err = p.threeDPainter(ctx, source, annotation, data)
+		if err != nil {
+			if ctx.Err() != nil {
+				return ctx.Err()
+			}
+			if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+				return err
+			}
+			p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF 3D rendering unavailable; normal appearance retained: " + err.Error()})
+		}
+	}
+	if err := p.paintedAnnotation(ctx, page, annotation, paint, action); err != nil {
+		return err
+	}
+	message := "PDF 3D appearance and original model retained; advanced interaction not transferred to OFD"
+	if paint != nil {
+		message = "PDF 3D static view and original model retained; interactive rendering not transferred to OFD"
+	}
+	p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: message})
+	return nil
+}
+
+// threeDPainter 准备三维静态图像，复用库层压缩，失败时不提交注解对象
+// 入参: ctx 取消上下文, source 三维参数, annotation 注解, data 原始模型
+// 返回: func(*pdfImporter) error 绘制回调, error 模型、绘制或资源错误
+func (p *pdfImporter) threeDPainter(ctx context.Context, source pdfgo.ThreeD, annotation pdfgo.Annotation, data []byte) (func(*pdfImporter) error, error) {
+	box := source.ViewBox
+	width, height := box.XMax-box.XMin, box.YMax-box.YMin
+	x, y := annotation.Rect.XMin/2+annotation.Rect.XMax/2, annotation.Rect.YMin/2+annotation.Rect.YMax/2
+	var nodes []pdfCompositeNode
+	if source.Background.RGB == nil {
+		return nil, &pdfgo.UnsupportedError{Feature: "3D background color space"}
+	}
+	if source.Background.EntireAnnotation {
+		r := annotation.Rect
+		path := pdfgo.Path{Segments: []pdfgo.Segment{
+			{Operator: "M", Points: []pdfgo.Point{{X: r.XMin, Y: r.YMin}}},
+			{Operator: "L", Points: []pdfgo.Point{{X: r.XMax, Y: r.YMin}}},
+			{Operator: "L", Points: []pdfgo.Point{{X: r.XMax, Y: r.YMax}}},
+			{Operator: "L", Points: []pdfgo.Point{{X: r.XMin, Y: r.YMax}}},
+			{Operator: "C"},
+		}}
+		nodes = append(nodes, pdfCompositeNode{path: &pdfgo.PathMark{Path: path, Fill: true, Style: pdfgo.Style{Fill: pdfgo.Paint{RGB: *source.Background.RGB, Alpha: 1}}}})
+	}
+	if width > 0 && height > 0 {
+		if source.Format != "U3D" {
+			return nil, &pdfgo.UnsupportedError{Feature: "3D model format " + string(source.Format)}
+		}
+		model, err := DecodeU3D(ctx, data, U3DOptions{})
+		if err != nil {
+			return nil, err
+		}
+		widthMM := width * math.Hypot(p.matrix[0], p.matrix[1])
+		heightMM := height * math.Hypot(p.matrix[2], p.matrix[3])
+		w, h := math.Ceil(widthMM*p.rasterDPI/25.4), math.Ceil(heightMM*p.rasterDPI/25.4)
+		if !finite(w) || !finite(h) || w <= 0 || h <= 0 || w > 1<<30 || h > 1<<30 {
+			return nil, fmt.Errorf("invalid PDF 3D raster dimensions")
+		}
+		img, err := RenderPDFThreeD(ctx, model, source, PDFThreeDRenderOptions{Width: int(w), Height: int(h)})
+		if err != nil {
+			return nil, err
+		}
+		resource, err := p.reader.CreateImage(ctx, img)
+		if err != nil {
+			return nil, err
+		}
+		nodes = append(nodes, pdfCompositeNode{image: &pdfgo.ImageMark{Image: resource, Matrix: pdfgo.Matrix{width, 0, 0, height, x + box.XMin, y + box.YMin}, Style: pdfgo.Style{Fill: pdfgo.Paint{Alpha: 1}}}})
+	}
+	return func(stamp *pdfImporter) error {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		return stamp.compositeObjects(nodes)
+	}, nil
+}
+
+// RenderPDFThreeD 按PDF相机、投影、背景与灯光绘制3DB区域，不执行脚本或动画
+// 返回图像不含3DB以外的注解背景，未支持的视图效果返回明确错误
+// 每次从传入场景建立独立节点状态，不继承此前绘制的运行时状态
+// 入参: ctx 取消上下文, model 解码后的U3D模型, source PDF三维参数, options 输出与资源限制
+// 返回: *image.RGBA 不透明图像, error 参数、能力、预算或取消错误
+func RenderPDFThreeD(ctx context.Context, model *U3DModel, source pdfgo.ThreeD, options PDFThreeDRenderOptions) (*image.RGBA, error) {
+	if ctx == nil {
+		return nil, fmt.Errorf("invalid PDF 3D render context")
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	if source.Format != "U3D" {
+		return nil, &pdfgo.UnsupportedError{Feature: "3D model format " + string(source.Format)}
+	}
+	presentation := source.Presentation
+	if presentation.RenderMode != "" && presentation.RenderMode != "Solid" || presentation.Overlay != nil {
+		return nil, &pdfgo.UnsupportedError{Feature: "3D view render mode or overlay"}
+	}
+	if source.Background.RGB == nil {
+		return nil, &pdfgo.UnsupportedError{Feature: "3D background color space"}
+	}
+	box := source.ViewBox
+	width, height := box.XMax-box.XMin, box.YMax-box.YMin
+	if !finite(width) || !finite(height) || width <= 0 || height <= 0 {
+		return nil, fmt.Errorf("invalid PDF 3D viewport")
+	}
+	projection := pdfgo.ThreeDProjection{Subtype: "P", Clipping: "ANF", FieldOfView: 90, PerspectiveBinding: "W"}
+	if source.Projection != nil {
+		projection = *source.Projection
+	}
+	render := U3DRenderOptions{Width: options.Width, Height: options.Height, MaxMemoryBytes: options.MaxMemoryBytes, MaxInstances: options.MaxInstances, Background: source.Background.RGB}
+	if err := pdfThreeDNodeStates(ctx, presentation.Nodes, &render); err != nil {
+		return nil, err
+	}
+	if err := pdfThreeDSections(ctx, presentation.CrossSections, &render); err != nil {
+		return nil, err
+	}
+	r, err := newU3DRender(ctx, model, render)
+	if err != nil {
+		return nil, err
+	}
+	camera, view, err := r.pdfCamera(source.Camera)
+	if err != nil {
+		return nil, err
+	}
+	render.View = view
+	camera.ScaleX, camera.ScaleY, camera.Near = 1, 1, 1
+	render.Camera = &camera
+	passes, err := r.selectView(render)
+	if err != nil {
+		return nil, err
+	}
+	if err := r.prepareSections(render.Sections); err != nil {
+		return nil, err
+	}
+	scale := 0.0
+	switch projection.Subtype {
+	case "P":
+		if !finite(projection.FieldOfView) || projection.FieldOfView <= 0 || projection.FieldOfView >= 180 {
+			return nil, &pdfgo.UnsupportedError{Feature: "degenerate 3D perspective field of view"}
+		}
+		diameter := projection.PerspectiveDiameter
+		if projection.PerspectiveBinding != "" {
+			diameter, err = pdfThreeDBinding(projection.PerspectiveBinding, width, height)
+			if err != nil {
+				return nil, err
+			}
+		}
+		if !finite(diameter) || diameter <= 0 {
+			return nil, fmt.Errorf("invalid PDF 3D perspective diameter")
+		}
+		scale = diameter / (2 * math.Tan(projection.FieldOfView*math.Pi/360))
+		camera.Perspective = true
+	case "O":
+		width := source.AnnotationBox.XMax - source.AnnotationBox.XMin
+		height := source.AnnotationBox.YMax - source.AnnotationBox.YMin
+		binding, err := pdfThreeDBinding(projection.OrthographicBinding, width, height)
+		if err != nil {
+			return nil, err
+		}
+		scale = projection.OrthographicScale * binding
+	default:
+		return nil, fmt.Errorf("invalid PDF 3D projection subtype")
+	}
+	camera.ScaleX = scale * float64(options.Width) / width
+	camera.ScaleY = scale * float64(options.Height) / height
+	switch projection.Clipping {
+	case "XNF":
+		camera.Near = 0
+		if projection.Near != nil {
+			camera.Near = *projection.Near
+		}
+		if !finite(camera.Near) || camera.Near < 0 || camera.Perspective && camera.Near == 0 {
+			return nil, fmt.Errorf("invalid PDF 3D near distance")
+		}
+		if projection.Far != nil {
+			camera.ClipFar = true
+			camera.Far = *projection.Far
+			if !finite(camera.Far) {
+				return nil, fmt.Errorf("invalid PDF 3D far distance")
+			}
+			if camera.Far < camera.Near {
+				passes, camera.Far = nil, 0
+				camera.ClipFar = false
+			}
+		}
+	case "ANF":
+		minimum, maximum, found, err := r.depthRange()
+		if err != nil {
+			return nil, err
+		}
+		if !found {
+			passes = nil
+		}
+		camera.Near = minimum
+		if camera.Perspective {
+			if maximum <= 0 {
+				passes = nil
+			}
+			camera.Near = max(1e-300, maximum*1e-9)
+			if minimum > 0 {
+				camera.Near = max(1e-300, minimum/2)
+			}
+		}
+		camera.Far = math.Nextafter(maximum, math.Inf(1))
+		if !finite(camera.Far) || camera.Far <= camera.Near {
+			camera.Far = 0
+		}
+	default:
+		return nil, fmt.Errorf("invalid PDF 3D clipping style")
+	}
+	if _, err := r.selectView(render); err != nil {
+		return nil, err
+	}
+	if source.Lighting.Subtype != "Artwork" && source.Lighting.Subtype != "" {
+		if err := r.reserve(uint64(len(source.Lighting.Lights)), 56); err != nil {
+			return nil, err
+		}
+		render.Lighting = &U3DLighting{DiffuseOffset: source.Lighting.Ambient, Lights: make([]U3DDirectionalLight, len(source.Lighting.Lights))}
+		for i, light := range source.Lighting.Lights {
+			if i%256 == 0 {
+				if err := ctx.Err(); err != nil {
+					return nil, err
+				}
+			}
+			direction := light.Direction
+			if light.CameraAttached {
+				direction = [3]float64{0, 0, 1}
+			}
+			render.Lighting.Lights[i] = U3DDirectionalLight{Color: light.Color, Direction: direction, CameraRelative: light.CameraAttached}
+		}
+	}
+	return r.render(render, passes)
+}
+
+// pdfThreeDBinding 计算目标区域的标准绑定倍率，不按模型包围盒重新适配
+// 入参: binding 绑定方式, width 区域宽度, height 区域高度
+// 返回: float64 倍率, error 方式或尺寸错误
+func pdfThreeDBinding(binding pdfgo.Name, width, height float64) (float64, error) {
+	if binding == "Absolute" {
+		return 1, nil
+	}
+	if !finite(width) || !finite(height) || width <= 0 || height <= 0 {
+		return 0, fmt.Errorf("invalid PDF 3D binding dimensions")
+	}
+	switch binding {
+	case "W":
+		return width, nil
+	case "H":
+		return height, nil
+	case "Min":
+		return min(width, height), nil
+	case "Max":
+		return max(width, height), nil
+	}
+	return 0, fmt.Errorf("invalid PDF 3D binding")
+}
+
+// pdfCamera 解析PDF相机来源并保留模型视图的绘制轮次
+// 入参: source 相机来源
+// 返回: U3DCamera 相机变换, string 视图节点, error 路径或变换错误
+func (r *u3dRender) pdfCamera(source pdfgo.ThreeDCamera) (U3DCamera, string, error) {
+	var camera U3DCamera
+	selected := -1
+	for i, node := range r.model.Nodes {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return camera, "", err
+			}
+		}
+		if node.Kind == "View" {
+			selected = i
+			break
+		}
+	}
+	if source.Source == "M" {
+		m := source.Matrix
+		camera.ToWorld = [16]float64{m[0], m[1], m[2], 0, m[3], m[4], m[5], 0, m[6], m[7], m[8], 0, m[9], m[10], m[11], 1}
+	} else {
+		if source.Source != "" && source.Source != "U3D" || source.Source == "U3D" && len(source.Path) == 0 {
+			return camera, "", fmt.Errorf("invalid PDF 3D camera source")
+		}
+		if source.Source == "U3D" {
+			selected = -1
+			for i, node := range r.model.Nodes {
+				if i%256 == 0 {
+					if err := r.ctx.Err(); err != nil {
+						return camera, "", err
+					}
+				}
+				if node.Name == source.Path[len(source.Path)-1] {
+					selected = i
+					break
+				}
+			}
+		}
+		if selected < 0 || r.model.Nodes[selected].Kind != "View" {
+			return camera, "", fmt.Errorf("missing PDF 3D camera node")
+		}
+		found := false
+		for _, index := range r.byNode[selected] {
+			if err := r.ctx.Err(); err != nil {
+				return camera, "", err
+			}
+			current, match := index, true
+			for j := len(source.Path) - 1; j >= 0; j-- {
+				if j%256 == 0 {
+					if err := r.ctx.Err(); err != nil {
+						return camera, "", err
+					}
+				}
+				if current < 0 || r.model.Nodes[r.scene[current].node].Name != source.Path[j] || r.model.Nodes[r.scene[current].node].Kind != "View" {
+					match = false
+					break
+				}
+				current = r.scene[current].parent
+			}
+			if source.Source == "U3D" && current >= 0 {
+				match = false
+			}
+			if !match {
+				continue
+			}
+			if found {
+				return camera, "", &pdfgo.UnsupportedError{Feature: "ambiguous 3D camera instance"}
+			}
+			camera.ToWorld, found = r.scene[index].world, true
+		}
+		if !found {
+			return camera, "", fmt.Errorf("missing PDF 3D camera path")
+		}
+	}
+	view := ""
+	if selected >= 0 {
+		view = r.model.Nodes[selected].Name
+	}
+	return camera, view, nil
+}
+
+// depthRange 计算可见模型面的相机深度范围，不为自动裁剪复制顶点
+// 返回: float64 最近深度, float64 最远深度, bool 是否含几何, error 几何或取消错误
+func (r *u3dRender) depthRange() (float64, float64, bool, error) {
+	minimum, maximum := math.Inf(1), math.Inf(-1)
+	for i, instance := range r.scene {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return 0, 0, false, err
+			}
+		}
+		node := r.model.Nodes[instance.node]
+		index, ok := r.meshes[node.Resource]
+		if node.Kind != "Model" || instance.modelVisibility(&node) == 0 || instance.opacity == 0 || !ok {
+			continue
+		}
+		mesh := &r.model.Meshes[index]
+		matrix := r.toCamera.multiply(instance.world)
+		for j, face := range mesh.Faces {
+			if j%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return 0, 0, false, err
+				}
+			}
+			for _, corner := range face.Corners {
+				if uint64(corner.Position) >= uint64(len(mesh.Positions)) {
+					return 0, 0, false, fmt.Errorf("invalid U3D position index")
+				}
+				p := mesh.Positions[corner.Position]
+				z := matrix[2]*float64(p[0]) + matrix[6]*float64(p[1]) + matrix[10]*float64(p[2]) + matrix[14]
+				if !finite(z) {
+					return 0, 0, false, fmt.Errorf("invalid U3D camera depth")
+				}
+				minimum, maximum = min(minimum, z), max(maximum, z)
+			}
+		}
+	}
+	for i, section := range r.sections {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return 0, 0, false, err
+			}
+		}
+		if section.opacity > 0 {
+			for _, corner := range section.corners {
+				minimum, maximum = min(minimum, corner.point[2]), max(maximum, corner.point[2])
+			}
+		}
+	}
+	if math.IsInf(minimum, 1) {
+		return 0, 0, false, nil
+	}
+	return minimum, maximum, true, nil
+}
+
+// pdfThreeDNodeStates 将PDF节点参数转为场景覆盖，转换缓存计入绘制预算
+// 入参: ctx 取消上下文, nodes 节点参数, options 绘制选项
+// 返回: error 预算或取消错误
+func pdfThreeDNodeStates(ctx context.Context, nodes []pdfgo.ThreeDNode, options *U3DRenderOptions) error {
+	if len(nodes) == 0 {
+		return nil
+	}
+	limit := options.MaxMemoryBytes
+	if limit == 0 {
+		limit = u3dDefaultBytes
+	}
+	if limit <= 0 || uint64(len(nodes)) >= uint64(limit)/168 {
+		return fmt.Errorf("PDF 3D node memory exceeds limit")
+	}
+	options.MaxMemoryBytes = limit - int64(len(nodes))*168
+	options.Nodes = make([]U3DNodeState, len(nodes))
+	for i, node := range nodes {
+		if i%256 == 0 {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+		}
+		state := U3DNodeState{Name: node.Name, Opacity: node.Opacity, Visible: node.Visible}
+		if node.Matrix != nil {
+			m := node.Matrix
+			state.Matrix = &[16]float64{m[0], m[1], m[2], 0, m[3], m[4], m[5], 0, m[6], m[7], m[8], 0, m[9], m[10], m[11], 1}
+		}
+		options.Nodes[i] = state
+	}
+	return nil
+}

ofdgo_pdf_3d_section.go

@@ -0,0 +1,70 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"context"
+	"fmt"
+	"math"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfThreeDSections 按XYZ顺序构造剖切方向，中心保持为世界坐标固定点
+// 入参: ctx 取消上下文, sections PDF剖切面, options 绘制选项
+// 返回: error 方向、预算或取消错误
+func pdfThreeDSections(ctx context.Context, sections []pdfgo.ThreeDCrossSection, options *U3DRenderOptions) error {
+	if len(sections) == 0 {
+		return nil
+	}
+	limit := options.MaxMemoryBytes
+	if limit == 0 {
+		limit = u3dDefaultBytes
+	}
+	if limit <= 0 || uint64(len(sections)) >= uint64(limit)/136 {
+		return fmt.Errorf("PDF 3D section memory exceeds limit")
+	}
+	options.MaxMemoryBytes = limit - int64(len(sections))*136
+	options.Sections = make([]U3DCrossSection, len(sections))
+	for i, source := range sections {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		if source.Axis < 0 || source.Axis > 2 {
+			return fmt.Errorf("invalid PDF 3D section axis")
+		}
+		section := U3DCrossSection{Center: source.Center, Color: source.Color, Opacity: source.Opacity}
+		section.AxisU[(source.Axis+1)%3], section.AxisV[(source.Axis+2)%3] = 1, 1
+		for axis, angle := range source.Rotation {
+			if axis == source.Axis {
+				continue
+			}
+			if !finite(angle) {
+				return fmt.Errorf("invalid PDF 3D section rotation")
+			}
+			sin, cos := math.Sincos(math.Remainder(angle, 360) * math.Pi / 180)
+			a, b := (axis+1)%3, (axis+2)%3
+			for _, vector := range []*[3]float64{&section.AxisU, &section.AxisV} {
+				vector[a], vector[b] = cos*vector[a]-sin*vector[b], sin*vector[a]+cos*vector[b]
+			}
+		}
+		if source.IntersectionVisible {
+			color := source.IntersectionColor
+			section.Intersection = &color
+		}
+		options.Sections[i] = section
+	}
+	return nil
+}

ofdgo_pdf_annot.go

@@ -29,6 +29,13 @@ import (
 // 入参: ctx 取消上下文, page PDF页面, annotation PDF注解, actions 外观区域的动作
 // 返回: error 外观或转换错误
 func (p *pdfImporter) appearanceAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation, actions ...Action) error {
+	return p.paintedAnnotation(ctx, page, annotation, nil, actions...)
+}
+
+// paintedAnnotation 复用注解坐标、标志与元数据处理，允许替换静态绘制内容
+// 入参: ctx 取消上下文, page PDF页面, annotation PDF注解, paint 绘制回调，空值使用原外观, actions 外观区域的动作
+// 返回: error 外观或转换错误
+func (p *pdfImporter) paintedAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation, paint func(*pdfImporter) error, actions ...Action) error {
 	for _, key := range []pdfgo.Name{"AA", "OC", "A"} {
 		if annotation.Subtype == "Widget" && (key == "A" || key == "AA") {
 			continue
@@ -74,6 +81,11 @@ func (p *pdfImporter) appearanceAnnotation(ctx context.Context, page *pdfgo.Page
 	stamp.compositeCache = nil
 	stamp.clipTexts = make(map[*pdfgo.TextClip][]TextObject)
 	stamp.pageWidth, stamp.pageHeight = box.W, box.H
+	if paint != nil {
+		if err := paint(&stamp); err != nil {
+			return err
+		}
+	} else {
 		nodes, err := p.collectCompositeNodes(func(visitor pdfgo.Visitor) error {
 			if annotation.Subtype == "Widget" {
 				visitor.MarkedContent = func(mark pdfgo.MarkedContentMark) error {
@@ -98,6 +110,7 @@ func (p *pdfImporter) appearanceAnnotation(ctx context.Context, page *pdfgo.Page
 		if err := stamp.compositeObjects(nodes); err != nil {
 			return err
 		}
+	}
 	if flags&(2|32) == 0 && !invisible {
 		p.compositeNodes = stamp.compositeNodes
 		p.transferBackdrop = stamp.transferBackdrop

ofdgo_pdf_buffer.go

@@ -25,6 +25,15 @@ type pdfObjectBuffer struct {
 	size  int
 }
 
+// objectValidation 在单次导入中共享不可变资源的校验结果，隔离局部编辑器
+// 返回: *editorValidation 当前编辑器的构建校验会话
+func (p *pdfImporter) objectValidation() *editorValidation {
+	if p.validation == nil || p.validation.Editor != p.editor {
+		p.validation = &editorValidation{Editor: p.editor}
+	}
+	return p.validation
+}
+
 // appendObject 追加本次导入对象，按需建立独立暂存缓冲
 // 入参: object 独立导入对象
 func (p *pdfImporter) appendObject(object GraphicObject) {

ofdgo_pdf_clip_group.go

@@ -51,7 +51,7 @@ func (p *pdfImporter) sharedClipObjects(objects []GraphicObject) ([]GraphicObjec
 		for index := range members {
 			*editorObjectClips(&members[index]) = nil
 		}
-		id, err := p.editor.addOwnedVector(p.ctx, members, p.pageWidth, p.pageHeight)
+		id, err := p.objectValidation().addOwnedVector(p.ctx, members, p.pageWidth, p.pageHeight)
 		if err != nil {
 			return nil, err
 		}

ofdgo_pdf_composite.go

@@ -33,6 +33,7 @@ type pdfCompositeNode struct {
 	children   []pdfCompositeNode
 	textObject *pdfgo.TextObject
 	glyph      *pdfgo.TextMark
+	formCount  int
 }
 
 // pdfCompositePixel 保存非预乘源空间分量及累计透明度
@@ -160,7 +161,15 @@ func (c *pdfCompositor) coverage(node pdfCompositeNode, stroke bool) (image.Imag
 	if geometry.scene == nil || b.X >= c.box.X+c.box.W || b.Y >= c.box.Y+c.box.H || b.X+b.W <= c.box.X || b.Y+b.H <= c.box.Y {
 		return nil, nil
 	}
-	return c.importer.renderGroupScene(geometry.scene, c.box)
+	target, err := c.acquireCoverage()
+	if err != nil {
+		return nil, err
+	}
+	coverage, err := c.importer.renderGroupSceneInto(geometry.scene, c.box, target)
+	if err != nil {
+		c.releaseCoverage(target)
+	}
+	return coverage, err
 }
 
 // geometry 缓存图元或组的实际覆盖场景与像素对齐边界
@@ -431,6 +440,17 @@ func (p *pdfImporter) collectCompositeNodes(walk func(pdfgo.Visitor) error) ([]p
 			nodes = append(nodes, pdfCompositeNode{group: &mark, children: children})
 			return nil
 		}
+		v.Form = func(_ pdfgo.FormMark, walk func(pdfgo.Visitor) error) error {
+			children, err := collect(walk)
+			if err != nil {
+				return err
+			}
+			if len(children) != 0 {
+				children[0].formCount = len(children)
+				nodes = append(nodes, children...)
+			}
+			return nil
+		}
 		err := walk(v)
 		return nodes, err
 	}
@@ -503,7 +523,19 @@ func (p *pdfImporter) compositePage(space *pdfgo.ColorSpace, walk func(pdfgo.Vis
 // 返回: error 转换或合成错误
 func (p *pdfImporter) compositeObjects(nodes []pdfCompositeNode) error {
 	space := p.compositeSpace
-	for i, node := range nodes {
+	for i := 0; i < len(nodes); i++ {
+		node := nodes[i]
+		if count := node.formCount; count >= 16 && count <= len(nodes)-i && !p.transferBackdrop {
+			packed, err := p.compositeForm(nodes[i : i+count])
+			if err != nil {
+				return fmt.Errorf("convert form at graphic %d: %w", i+1, err)
+			}
+			if packed {
+				p.compositeNodes = append(p.compositeNodes, nodes[i:i+count]...)
+				i += count - 1
+				continue
+			}
+		}
 		direct, err := p.directCompositeNode(node, space)
 		if err != nil {
 			return fmt.Errorf("inspect graphic %d: %w", i+1, err)

ofdgo_pdf_composite_draw.go

@@ -109,6 +109,7 @@ func (c *pdfCompositor) drawPaint(node pdfCompositeNode, outline bool, paint pdf
 	if err != nil || coverage == nil {
 		return err
 	}
+	defer c.releaseCoverage(coverage)
 	style, _, _ := node.style()
 	var transfer *pdfgo.TransferFunction
 	imageShape := false
@@ -198,7 +199,7 @@ func (c *pdfCompositor) drawPaint(node pdfCompositeNode, outline bool, paint pdf
 			return err
 		}
 		for x := region.Min.X; x < region.Max.X; x++ {
-			_, _, _, a := coverage.At(x, y).RGBA()
+			a := imageAlphaAt(coverage, x, y)
 			if a == 0 {
 				continue
 			}

ofdgo_pdf_composite_scratch.go

@@ -14,6 +14,8 @@
 
 package ofdgo
 
+import "image"
+
 // pdfCompositeTileSize 限定单次合成块的像素边长
 const pdfCompositeTileSize = 256
 
@@ -24,6 +26,49 @@ type pdfCompositeBuffers[T any] [8][]T
 type pdfCompositeScratch struct {
 	pixels  pdfCompositeBuffers[pdfCompositePixel]
 	masks   pdfCompositeBuffers[float64]
+	rasters [8]*image.RGBA
+}
+
+// acquireCoverage 借用当前块的独占画布，保留活动画布供嵌套合成读取
+// 返回: *image.RGBA 未清空画布，不支持缓冲绘制的后端返回nil, error 无效绘制区域
+func (c *pdfCompositor) acquireCoverage() (*image.RGBA, error) {
+	if _, ok := c.importer.editor.Backends().Raster.(RasterBufferBackend); !ok {
+		return nil, nil
+	}
+	page := RasterPage{Width: c.box.W, Height: c.box.H, DPI: c.importer.rasterDPI}
+	w, h, err := page.PixelSize()
+	if err != nil {
+		return nil, err
+	}
+	if c.scratch == nil {
+		c.scratch = &pdfCompositeScratch{}
+	}
+	rect := image.Rect(0, 0, w, h)
+	for i, stored := range c.scratch.rasters {
+		if stored != nil && stored.Rect == rect {
+			c.scratch.rasters[i] = nil
+			return stored, nil
+		}
+	}
+	return image.NewRGBA(rect), nil
+}
+
+// releaseCoverage 归还当前调用不再读取的画布，限制单次合成保留的内存
+// 入参: coverage 当前调用的覆盖图像
+func (c *pdfCompositor) releaseCoverage(coverage image.Image) {
+	if _, ok := c.importer.editor.Backends().Raster.(RasterBufferBackend); !ok || c.scratch == nil {
+		return
+	}
+	buffer, ok := coverage.(*image.RGBA)
+	if !ok || buffer == nil || cap(buffer.Pix) > 4*pdfCompositeTileSize*pdfCompositeTileSize {
+		return
+	}
+	for i, stored := range c.scratch.rasters {
+		if stored == nil {
+			c.scratch.rasters[i] = buffer
+			return
+		}
+	}
 }
 
 // acquire 借用尚未初始化的独立缓冲，嵌套调用不复用活动缓冲

ofdgo_pdf_composite_shading.go

@@ -80,6 +80,7 @@ func (c *pdfCompositor) shadingPattern(pattern *pdfgo.ShadingPattern, node pdfCo
 		c.releasePixels(result)
 		return nil, err
 	}
+	defer c.releaseCoverage(coverage)
 	step := 25.4 / c.importer.rasterDPI
 	for i := range result {
 		if i%pdfCompositeTileSize == 0 {
@@ -90,7 +91,7 @@ func (c *pdfCompositor) shadingPattern(pattern *pdfgo.ShadingPattern, node pdfCo
 		}
 		shape := 0.0
 		if coverage != nil {
-			_, _, _, a := coverage.At(i%c.width, i/c.width).RGBA()
+			a := imageAlphaAt(coverage, i%c.width, i/c.width)
 			shape = float64(a) / 65535
 		}
 		if nodes[0].image != nil && shape != 0 {

ofdgo_pdf_form.go

@@ -0,0 +1,142 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"encoding/xml"
+)
+
+// pdfFormBufferLimit 限制表单编码暂存容量，不限制资源大小
+const pdfFormBufferLimit = 8 << 20
+
+// pdfFormResource 保存生成内容及资源编号，复用前核对完整内容
+type pdfFormResource struct {
+	content []byte
+	id      string
+}
+
+// pdfFormCache 隔离编辑器的表单资源，复用编码缓冲而不共享缓存内容
+type pdfFormCache struct {
+	editor  *Editor
+	entries renderCache[[32]byte, pdfFormResource]
+	buffer  bytes.Buffer
+}
+
+// encode 按原顺序编码对象分块，不为缓存检查整理连续对象数组
+// 入参: ctx 取消上下文, objects 表单对象, width 页面宽度, height 页面高度
+// 返回: []byte 下次编码或重置前有效的内容, error 编码或取消错误
+func (c *pdfFormCache) encode(ctx context.Context, objects *pdfObjectBuffer, width, height float64) ([]byte, error) {
+	c.buffer.Reset()
+	x := newOFDXML(&c.buffer)
+	x.ctx = ctx
+	x.root("Content", ofdAttrs{{Name: xml.Name{Local: "Width"}, Value: ofdNumber(width)},
+		{Name: xml.Name{Local: "Height"}, Value: ofdNumber(height)}})
+	for _, part := range objects.parts {
+		for _, object := range part {
+			x.object(object, false)
+			if x.err != nil {
+				return nil, x.err
+			}
+		}
+	}
+	x.end("Content")
+	if err := x.finish(); err != nil {
+		return nil, err
+	}
+	return c.buffer.Bytes(), nil
+}
+
+// reset 清空临时内容，释放超限缓冲，不修改已登记资源
+func (c *pdfFormCache) reset() {
+	if c.buffer.Cap() > pdfFormBufferLimit {
+		c.buffer = bytes.Buffer{}
+	} else {
+		c.buffer.Reset()
+	}
+}
+
+// compositeForm 将无需背景合成的普通表单保存为矢量资源，保留图元的实际坐标和裁剪
+// 入参: nodes 普通表单连续图元
+// 返回: bool 是否已保存为复合对象, error 检查或转换错误
+func (p *pdfImporter) compositeForm(nodes []pdfCompositeNode) (bool, error) {
+	if pdfCompositeHasTransfer(nodes) {
+		return false, nil
+	}
+	for _, node := range nodes {
+		if err := p.ctx.Err(); err != nil {
+			return false, err
+		}
+		direct, err := p.directCompositeNode(node, p.compositeSpace)
+		if err != nil || !direct {
+			return false, err
+		}
+	}
+	if err := p.flushPath(); err != nil {
+		return false, err
+	}
+	parent := p.objects
+	p.objects = nil
+	defer func() { p.objects = parent }()
+	visitor := p.visitor()
+	for _, node := range nodes {
+		if err := node.emit(visitor); err != nil {
+			return false, err
+		}
+	}
+	if err := p.flushPath(); err != nil {
+		return false, err
+	}
+	if err := p.ctx.Err(); err != nil {
+		return false, err
+	}
+	if p.objects.len() == 0 {
+		return true, nil
+	}
+	if p.formResources == nil || p.formResources.editor != p.editor {
+		p.formResources = &pdfFormCache{editor: p.editor, entries: renderCache[[32]byte, pdfFormResource]{limit: 32 << 20}}
+	}
+	cache := p.formResources
+	defer cache.reset()
+	content, err := cache.encode(p.ctx, p.objects, p.pageWidth, p.pageHeight)
+	if err != nil {
+		return false, err
+	}
+	key := sha256.Sum256(content)
+	resource, found := cache.entries.get(key)
+	if !found || !bytes.Equal(resource.content, content) {
+		objects, err := p.objects.data(p.ctx)
+		if err != nil {
+			return false, err
+		}
+		id, err := p.objectValidation().addOwnedVector(p.ctx, objects, p.pageWidth, p.pageHeight)
+		if err != nil {
+			return false, err
+		}
+		resource = pdfFormResource{id: id}
+		if len(content) <= cache.entries.limit-len(id)-128 {
+			resource.content = bytes.Clone(content)
+			cache.entries.put(key, resource, cap(resource.content)+len(id)+128)
+		}
+	}
+	p.objects = parent
+	p.appendObject(GraphicObject{Type: "CompositeObject", CompositeGraphicUnit: CompositeGraphicUnit{
+		Boundary: pdfBoundary(Box{W: p.pageWidth, H: p.pageHeight}), ResourceID: resource.id,
+	}})
+	parent = p.objects
+	return true, nil
+}

ofdgo_pdf_geometry.go

@@ -158,11 +158,24 @@ func (p *pdfImporter) compileCoverage(node pdfCompositeNode, stroke bool) (*Rast
 			}
 			evenOdd = false
 		}
+		var clipped GeometryPath
+		var linear bool
+		var clipErr error
+		if rectangle {
+			clipped, linear, clipErr = clipLinearFillGeometry(path, clip)
+		}
+		if clipErr != nil {
+			return nil, Box{}, clipErr
+		}
+		if linear {
+			path = clipped
+		} else {
 			path, err = clipGeometry(geometry, path, &clip)
 			if err != nil {
 				return nil, Box{}, err
 			}
 		}
+	}
 	if err := compiler.command(path, Paint{Color: color.RGBA{255, 255, 255, 255}}, evenOdd, nil, IdentityMatrix, nil); err != nil {
 		return nil, Box{}, err
 	}

ofdgo_pdf_group.go

@@ -435,6 +435,13 @@ func (p *pdfImporter) groupSceneBounds(scene *RasterPage) (*RasterPage, Box, err
 // 入参: source 原始场景, box 页面裁取区域
 // 返回: image.Image 透明图像, error 后端渲染错误
 func (p *pdfImporter) renderGroupScene(source *RasterPage, box Box) (image.Image, error) {
+	return p.renderGroupSceneInto(source, box, nil)
+}
+
+// renderGroupSceneInto 在指定区域绘制场景，按所选后端能力复用独占目标
+// 入参: source 原始场景, box 页面裁取区域, target 可选目标缓冲
+// 返回: image.Image 透明图像, error 后端渲染错误
+func (p *pdfImporter) renderGroupSceneInto(source *RasterPage, box Box, target *image.RGBA) (image.Image, error) {
 	scene := *source
 	scene.DPI = p.rasterDPI
 	scene.Commands = append([]RasterCommand(nil), source.Commands...)
@@ -457,6 +464,14 @@ func (p *pdfImporter) renderGroupScene(source *RasterPage, box Box) (image.Image
 	if backend == nil {
 		return nil, fmt.Errorf("PDF local compositing: %w", ErrBackendUnavailable)
 	}
+	if target != nil {
+		if buffered, ok := backend.(RasterBufferBackend); ok {
+			if err := buffered.RenderInto(&scene, target); err != nil {
+				return nil, err
+			}
+			return target, nil
+		}
+	}
 	return backend.Render(&scene)
 }
 

ofdgo_pdf_media.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"math"
 	"net/url"
@@ -134,33 +135,19 @@ func (p *pdfImporter) movieAnnotation(ctx context.Context, page *pdfgo.Page, ann
 // 入参: ctx 取消上下文, page PDF页面, annotation 交互注解, strict 严格检查开关
 // 返回: error 外观、资源或不可等价转换错误
 func (p *pdfImporter) interactiveAnnotation(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation, strict bool) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
 	if strict {
 		return &pdfgo.UnsupportedError{Feature: "interactive " + string(annotation.Subtype) + " conversion"}
 	}
 	var actions []Action
 	if annotation.Subtype == "3D" {
-		model, err := p.reader.ReadThreeD(annotation)
+		return p.threeDAnnotation(ctx, page, annotation)
-		if err != nil {
-			p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF 3D metadata unavailable; static appearance retained: " + err.Error()})
-			return p.appearanceAnnotation(ctx, page, annotation)
-		}
-		data, err := model.Stream.Decode()
-		if err != nil {
-			return err
-		}
-		id, err := p.editor.AddAttachment(fmt.Sprintf("Model_%d.%s", p.page+1, strings.ToLower(string(model.Format))), data)
-		if err != nil {
-			return err
-		}
-		actions = append(actions, Action{Event: "CLICK", GotoA: &GotoA{AttachID: id}})
 	} else {
 		media, err := p.reader.ReadRichMedia(ctx, annotation)
 		if err != nil {
-			if ctx.Err() != nil {
+			return p.interactiveAppearanceFallback(ctx, page, annotation, "metadata", err)
-				return ctx.Err()
-			}
-			p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: "PDF rich media metadata unavailable; static appearance retained: " + err.Error()})
-			return p.appearanceAnnotation(ctx, page, annotation)
 		}
 		config := media.Configurations[media.ActiveConfiguration]
 		var playing *pdfgo.FileSpecification
@@ -245,6 +232,23 @@ func (p *pdfImporter) interactiveAnnotation(ctx context.Context, page *pdfgo.Pag
 	return nil
 }
 
+// interactiveAppearanceFallback 保留交互注解的有效正常外观，取消时不继续转换
+// 入参: ctx 取消上下文, page PDF页面, annotation 交互注解, kind 失败资源类型, cause 原始错误
+// 返回: error 取消或外观转换错误
+func (p *pdfImporter) interactiveAppearanceFallback(ctx context.Context, page *pdfgo.Page, annotation pdfgo.Annotation, kind string, cause error) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	if errors.Is(cause, context.Canceled) || errors.Is(cause, context.DeadlineExceeded) {
+		return cause
+	}
+	if err := p.appearanceAnnotation(ctx, page, annotation); err != nil {
+		return err
+	}
+	p.warning(pdfgo.Diagnostic{Page: p.page + 1, Message: fmt.Sprintf("PDF %s %s unavailable; normal appearance retained: %v", annotation.Subtype, kind, cause)})
+	return nil
+}
+
 // mediaData 读取媒体或附件，宽松模式缺少外部读取器时报告资源不可用
 // 入参: ctx 取消上下文, file PDF文件说明
 // 返回: []byte 原始文件, bool 是否可用, error 解码、外部读取或严格模式错误

ofdgo_pdf_object.go

@@ -252,10 +252,7 @@ func (p *pdfImporter) text(mark pdfgo.TextMark) error {
 		if err := p.flushPath(); err != nil {
 			return err
 		}
-		visitor := pdfgo.Visitor{Path: p.path, Image: p.image, Warning: p.warning, Reference: p.referencePage}
+		visitor := p.visitor()
-		visitor.Group = func(group pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
-			return p.group(group, walk, visitor)
-		}
 		for index := range mark.Glyphs {
 			if err := p.reader.WalkType3Glyph(p.ctx, mark, index, visitor); err != nil {
 				return err

ofdgo_renderer_cache_canvas.go

@@ -0,0 +1,70 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"math"
+
+	"github.com/tdewolff/canvas"
+)
+
+// canvasGeometryDigest 按完整坐标、路径顺序及几何容差计算摘要
+// 入参: paths 非空路径序列
+// 返回: [32]byte 几何摘要
+func canvasGeometryDigest(paths ...*canvas.Path) [32]byte {
+	hash := sha256.New()
+	var data [512]byte
+	binary.LittleEndian.PutUint64(data[:8], math.Float64bits(canvas.Tolerance))
+	binary.LittleEndian.PutUint64(data[8:16], math.Float64bits(canvas.Epsilon))
+	binary.LittleEndian.PutUint64(data[16:24], math.Float64bits(canvas.BentleyOttmannEpsilon))
+	hash.Write(data[:24])
+	for _, path := range paths {
+		values := path.Data()
+		binary.LittleEndian.PutUint64(data[:8], uint64(len(values)))
+		hash.Write(data[:8])
+		for len(values) > 0 {
+			count := min(len(values), len(data)/8)
+			for i, value := range values[:count] {
+				binary.LittleEndian.PutUint64(data[i*8:], math.Float64bits(value))
+			}
+			hash.Write(data[:count*8])
+			values = values[count:]
+		}
+	}
+	var key [32]byte
+	hash.Sum(key[:0])
+	return key
+}
+
+// settleCanvasPath 复用复杂路径的填充规范化结果，返回独立副本
+// 入参: path 页面坐标路径, rule 填充规则
+// 返回: *canvas.Path 规范化填充轮廓
+func (r *Renderer) settleCanvasPath(path *canvas.Path, rule canvas.FillRule) *canvas.Path {
+	if len(path.Data()) < 256 {
+		return path.Settle(rule)
+	}
+	key := canvasFillKey{digest: canvasGeometryDigest(path), rule: rule}
+	cache := r.canvasSettledPaths()
+	if result, ok := cache.get(key); ok {
+		return result.Copy()
+	}
+	result := path.Settle(rule)
+	if cost := len(result.Data())*8 + 256; cost <= cache.limit {
+		cache.put(key, result.Copy(), cost)
+	}
+	return result
+}

ofdgo_renderer_canvas.go

@@ -55,6 +55,30 @@ func (b CanvasBackend) Render(page *RasterPage) (image.Image, error) {
 		return nil, err
 	}
 	img := image.NewRGBA(image.Rect(0, 0, w, h))
+	return b.renderImage(page, img)
+}
+
+// RenderInto 在调用方独占的紧密RGBA缓冲中重新绘制，不修改页面或保留缓冲
+// 入参: page 只读页面, target 原点为零且尺寸匹配的目标，不与输入图像共享数据
+// 返回: error 参数或绘制错误，绘制失败时目标可能包含部分结果
+func (b CanvasBackend) RenderInto(page *RasterPage, target *image.RGBA) error {
+	w, h, err := page.PixelSize()
+	if err != nil {
+		return err
+	}
+	if target == nil || target.Rect != image.Rect(0, 0, w, h) || target.Stride != 4*w || len(target.Pix) < 4*w*h {
+		return fmt.Errorf("invalid canvas target buffer")
+	}
+	clear(target.Pix[:4*w*h])
+	_, err = b.renderImage(page, target)
+	return err
+}
+
+// renderImage 将页面绘制到已清空且尺寸匹配的目标
+// 入参: page 只读页面, img 独占目标
+// 返回: image.Image 目标图像, error 绘制错误
+func (b CanvasBackend) renderImage(page *RasterPage, img *image.RGBA) (image.Image, error) {
+	h := img.Rect.Dy()
 	space := b.ColorSpace
 	if space == nil {
 		space = canvas.DefaultColorSpace

ofdgo_renderer_clip_canvas.go

@@ -15,10 +15,7 @@
 package ofdgo
 
 import (
-	"crypto/sha256"
-	"encoding/binary"
 	"image"
-	"math"
 	"slices"
 
 	"github.com/tdewolff/canvas"
@@ -195,27 +192,7 @@ func (r *Renderer) intersectCachedClipPath(parent, current *canvas.Path) *canvas
 	if parent == nil || current == nil || len(parent.Data())+len(current.Data()) < 256 {
 		return intersectClipPath(parent, current)
 	}
-	hash := sha256.New()
+	key := canvasGeometryDigest(parent, current)
-	var data [512]byte
-	binary.LittleEndian.PutUint64(data[:8], math.Float64bits(canvas.Tolerance))
-	binary.LittleEndian.PutUint64(data[8:16], math.Float64bits(canvas.Epsilon))
-	binary.LittleEndian.PutUint64(data[16:24], math.Float64bits(canvas.BentleyOttmannEpsilon))
-	hash.Write(data[:24])
-	for _, path := range []*canvas.Path{parent, current} {
-		values := path.Data()
-		binary.LittleEndian.PutUint64(data[:8], uint64(len(values)))
-		hash.Write(data[:8])
-		for len(values) > 0 {
-			count := min(len(values), len(data)/8)
-			for i, value := range values[:count] {
-				binary.LittleEndian.PutUint64(data[i*8:], math.Float64bits(value))
-			}
-			hash.Write(data[:count*8])
-			values = values[count:]
-		}
-	}
-	var key [32]byte
-	hash.Sum(key[:0])
 	cache := r.canvasClipIntersections()
 	if path, ok := cache.get(key); ok {
 		return path.Copy()
@@ -310,6 +287,8 @@ func applyClipPath(path, clip *canvas.Path) *canvas.Path {
 	if path == nil || clip == nil {
 		return path
 	}
+	path = reduceRepeatedNonZeroPath(path)
+	clip = reduceRepeatedNonZeroPath(clip)
 	if slices.Equal(path.Data(), clip.Data()) {
 		return path
 	}
@@ -340,6 +319,36 @@ func applyClipPath(path, clip *canvas.Path) *canvas.Path {
 	return path.And(clip)
 }
 
+// reduceRepeatedNonZeroPath 将完全相同的闭合轮廓约为一份，保持非零填充区域
+// 入参: path 非零填充路径
+// 返回: *canvas.Path 等价填充路径
+func reduceRepeatedNonZeroPath(path *canvas.Path) *canvas.Path {
+	if path == nil {
+		return path
+	}
+	data := path.Data()
+	if len(data) < 8 || data[0] != canvas.MoveToCmd {
+		return path
+	}
+	end := 0
+	scanner := path.Scanner()
+	for scanner.Scan() {
+		if scanner.Cmd() == canvas.MoveToCmd && end != 0 {
+			break
+		}
+		end += len(scanner.Values()) + 2
+	}
+	if end == len(data) || data[end-1] != canvas.CloseCmd || len(data)%end != 0 {
+		return path
+	}
+	for i := end; i < len(data); i += end {
+		if !slices.Equal(data[:end], data[i:i+end]) {
+			return path
+		}
+	}
+	return canvas.NewPathFromData(slices.Clone(data[:end]))
+}
+
 // applyFillClipPath 为多段描边直接填充裁剪，不将相消轮廓用于几何测量
 // 入参: path 非零填充描边, clip 裁剪路径
 // 返回: *canvas.Path 绘制轮廓

ofdgo_renderer_geom_canvas.go

@@ -400,6 +400,25 @@ func geometryFromCanvasPath(path *canvas.Path) *GeometryPath {
 	return &result
 }
 
+// clipLinearFillGeometry 裁剪直线填充轮廓，保留原填充规则，不用于区域布尔运算
+// 入参: path 闭合绘制轮廓, clip 凸裁剪窗口
+// 返回: GeometryPath 填充轮廓, bool 是否适用, error 路径错误
+func clipLinearFillGeometry(path, clip GeometryPath) (GeometryPath, bool, error) {
+	a, err := geometryToCanvasPath(&path)
+	if err != nil {
+		return nil, false, err
+	}
+	b, err := geometryToCanvasPath(&clip)
+	if err != nil {
+		return nil, false, err
+	}
+	result, ok := intersectLinearCanvasContours(a, b)
+	if !ok {
+		return nil, false, nil
+	}
+	return *geometryFromCanvasPath(result), true, nil
+}
+
 // actionCanvasMatrix 转换页面坐标矩阵，不翻转Y轴
 // 入参: matrix 页面变换
 // 返回: canvas.Matrix 路径变换

ofdgo_renderer_path_canvas.go

@@ -253,13 +253,16 @@ func (r *Renderer) renderPath(ctx *canvas.Context, obj PathObject, pageH float64
 		}
 		fp := paths.Merge()
 		fillRule := canvas.NonZero
+		if fillClip != nil && !fp.Bounds().Overlaps(fillClip.Bounds()) {
+			fp = &canvas.Path{}
+		}
 		if obj.Rule == "Even-Odd" {
 			fillRule = canvas.EvenOdd
 			if bounds, ok := rectangularPath(fillClip); ok && bounds.Contains(fp.Bounds()) {
 				fillClip = nil
 			}
 			if fillClip != nil || style.fillPattern != nil {
-				fp = fp.Settle(fillRule)
+				fp = r.settleCanvasPath(fp, fillRule)
 			}
 		}
 		if fillClip != nil {

ofdgo_renderer_state_canvas.go

@@ -33,6 +33,15 @@ type canvasClipCacheKey struct{}
 // canvasPathCacheKey 区分不依赖文档资源的共享局部路径缓存
 type canvasPathCacheKey struct{}
 
+// canvasFillCacheKey 区分按填充规则规范化的共享路径缓存
+type canvasFillCacheKey struct{}
+
+// canvasFillKey 保存完整几何摘要及填充规则
+type canvasFillKey struct {
+	digest [32]byte
+	rule   canvas.FillRule
+}
+
 // canvasPathKey 按完整路径文本与几何容差区分解析结果
 type canvasPathKey struct {
 	data    string
@@ -78,6 +87,21 @@ func (r *Renderer) canvasParsedPaths() *renderCache[canvasPathKey, *canvas.Path]
 	return cache
 }
 
+// canvasSettledPaths 获取共享填充轮廓缓存，限制结果保留量
+// 返回: *renderCache[canvasFillKey, *canvas.Path] 填充轮廓缓存
+func (r *Renderer) canvasSettledPaths() *renderCache[canvasFillKey, *canvas.Path] {
+	key := canvasFillCacheKey{}
+	if state, ok := r.sharedBackendStates[key]; ok {
+		return state.(*renderCache[canvasFillKey, *canvas.Path])
+	}
+	if r.sharedBackendStates == nil {
+		r.sharedBackendStates = make(map[any]any)
+	}
+	cache := &renderCache[canvasFillKey, *canvas.Path]{limit: 16 << 20}
+	r.sharedBackendStates[key] = cache
+	return cache
+}
+
 // canvasFontFamilies 获取子渲染器共享的只读字体族缓存，限制解析数据保留量
 // 返回: *renderCache[canvasFontKey, *canvas.FontFamily] 字体族缓存
 func (r *Renderer) canvasFontFamilies() *renderCache[canvasFontKey, *canvas.FontFamily] {

ofdgo_u3d.go

@@ -0,0 +1,589 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"math"
+)
+
+// u3dDefaultBytes 限制默认解码数据规模，不包括调用方已有输入及运行时开销
+const u3dDefaultBytes = 256 << 20
+
+// U3DOptions 控制U3D解码规模，MaxDecodedBytes为0时采用256MiB上限
+type U3DOptions struct {
+	MaxDecodedBytes int64
+}
+
+// U3DModel 保存独立于PDF的静态U3D场景，不执行动作或读取外部文件
+type U3DModel struct {
+	Major, Minor int16
+	DefinedUnits bool
+	Units        float64
+	Meshes       []U3DMesh
+	Nodes        []U3DNode
+	Materials    []U3DMaterial
+	Shaders      []U3DShader
+	Lights       []U3DLight
+	Views        []U3DViewResource
+	Metadata     []U3DMetadata
+}
+
+// U3DMetadata 保留块所属名称与原始元数据，数据不与输入共享存储
+type U3DMetadata struct {
+	Block uint32
+	Name  string
+	Data  []byte
+}
+
+// U3DNode 保存组、模型、光源或视图节点，父节点矩阵按列存储
+type U3DNode struct {
+	Name, Kind, Resource string
+	Parents              []U3DParent
+	Visibility           uint32
+	Shaders              [][]string
+	View                 *U3DView
+}
+
+// U3DParent 保存父节点名称及局部到父节点的变换，空名称引用默认节点
+type U3DParent struct {
+	Name      string
+	Transform [16]float32
+}
+
+// U3DMaterial 保存材质参数，Attributes各位决定相应参数是否生效
+type U3DMaterial struct {
+	Name                                 string
+	Attributes                           uint32
+	Ambient, Diffuse, Specular, Emissive [3]float32
+	Reflectivity, Opacity                float32
+}
+
+// U3DShader 保存无纹理着色器参数，不提前应用混合、透明测试或光照
+type U3DShader struct {
+	Name, Material                   string
+	Attributes, AlphaFunction, Blend uint32
+	RenderPass                       uint32
+	AlphaReference                   float32
+}
+
+// U3DLight 保存环境、方向、点或聚光资源，Kind依次为0至3
+type U3DLight struct {
+	Name                 string
+	Attributes           uint32
+	Kind                 byte
+	Color, Attenuation   [3]float32
+	SpotAngle, Intensity float32
+}
+
+// u3dBlock 保存校验后的块边界，数据切片仅在解码期间引用输入
+type u3dBlock struct {
+	kind       uint32
+	data, meta []byte
+}
+
+// u3dDecoder 保存单次解码预算及场景索引，不跨调用缓存输入
+type u3dDecoder struct {
+	ctx       context.Context
+	model     U3DModel
+	remaining uint64
+	plain     bool
+	meshes    map[string]*u3dMeshDeclaration
+	meshOrder []string
+	nodes     map[string]int
+	palettes  map[uint32]map[string]bool
+}
+
+// DecodeU3D 按ECMA-363解码静态基础网格、组、材质、着色器和光源
+// 暂不支持渐进网格、纹理和动画，遇到未支持内容返回错误而非部分场景
+// 入参: ctx 取消上下文, data U3D数据, options 解码限制
+// 返回: *U3DModel 独立场景数据, error 格式、能力、预算或取消错误
+func DecodeU3D(ctx context.Context, data []byte, options U3DOptions) (*U3DModel, error) {
+	if ctx == nil || options.MaxDecodedBytes < 0 {
+		return nil, fmt.Errorf("invalid U3D decode options")
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	limit := options.MaxDecodedBytes
+	if limit == 0 {
+		limit = u3dDefaultBytes
+	}
+	d := u3dDecoder{ctx: ctx, remaining: uint64(limit), meshes: make(map[string]*u3dMeshDeclaration), nodes: make(map[string]int), palettes: make(map[uint32]map[string]bool)}
+	header, next, err := u3dReadBlock(data, 0)
+	if err != nil {
+		return nil, err
+	}
+	if header.kind != 0x00443355 {
+		return nil, fmt.Errorf("invalid U3D file header")
+	}
+	r := u3dValues{data: header.data}
+	version, profile := r.u32(), r.u32()
+	d.model.Major, d.model.Minor = int16(version), int16(version>>16)
+	if d.model.Major > 0 || profile & ^uint32(14) != 0 {
+		return nil, fmt.Errorf("unsupported U3D version or profile")
+	}
+	declarationEnd := uint64(r.u32())
+	fileSize := uint64(r.u32())
+	fileSize |= uint64(r.u32()) << 32
+	if r.u32() != 106 {
+		return nil, fmt.Errorf("unsupported U3D character encoding")
+	}
+	d.plain = profile&4 != 0
+	d.model.DefinedUnits, d.model.Units = profile&8 != 0, 1
+	if d.model.DefinedUnits {
+		unitBytes := r.take(8)
+		if r.err == nil {
+			d.model.Units = math.Float64frombits(binary.LittleEndian.Uint64(unitBytes))
+			if !finite(d.model.Units) || d.model.Units <= 0 {
+				return nil, fmt.Errorf("invalid U3D units")
+			}
+		}
+	}
+	if err := r.done(); err != nil {
+		return nil, err
+	}
+	if fileSize != uint64(len(data)) || declarationEnd < uint64(next) || declarationEnd > fileSize || declarationEnd%4 != 0 {
+		return nil, fmt.Errorf("invalid U3D file size")
+	}
+	if err := d.metadata(header, ""); err != nil {
+		return nil, err
+	}
+	priority := uint32(0)
+	for offset := next; offset < len(data); {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
+		block, end, err := u3dReadBlock(data, offset)
+		if err != nil {
+			return nil, fmt.Errorf("U3D block at %d: %w", offset, err)
+		}
+		continuation := block.kind == 0xffffff15 || block.kind == 0xffffff3b || block.kind == 0xffffff3c
+		if uint64(offset) < declarationEnd && (uint64(end) > declarationEnd || continuation) || uint64(offset) >= declarationEnd && !continuation {
+			return nil, fmt.Errorf("invalid U3D declaration boundary at %d", offset)
+		}
+		if block.kind == 0xffffff15 {
+			r := u3dValues{data: block.data}
+			value := r.u32()
+			if err := r.done(); err != nil {
+				return nil, err
+			}
+			if value == 0 || value < priority || value > 0x7fffffff {
+				return nil, fmt.Errorf("invalid U3D block priority")
+			}
+			priority = value
+			err = d.metadata(block, "")
+		} else if block.kind == 0xffffff14 {
+			err = d.chain(block)
+		} else {
+			_, err = d.block(block, "", -1, 0)
+		}
+		if err != nil {
+			return nil, fmt.Errorf("U3D block %#x at %d: %w", block.kind, offset, err)
+		}
+		offset = end
+	}
+	for _, name := range d.meshOrder {
+		mesh := d.meshes[name]
+		if !mesh.decoded && mesh.counts[1] != 0 {
+			return nil, fmt.Errorf("missing U3D base mesh %q", name)
+		}
+		d.model.Meshes = append(d.model.Meshes, mesh.mesh)
+	}
+	if err := d.checkParents(); err != nil {
+		return nil, err
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return &d.model, nil
+}
+
+// u3dReadBlock 按64位长度计算校验块数据与零填充，避免长度溢出
+// 入参: data 块序列, offset 块起点
+// 返回: u3dBlock 块, int 下一块起点, error 边界或填充错误
+func u3dReadBlock(data []byte, offset int) (u3dBlock, int, error) {
+	if offset < 0 || offset > len(data) || len(data)-offset < 12 {
+		return u3dBlock{}, 0, io.ErrUnexpectedEOF
+	}
+	header := data[offset : offset+12]
+	size, meta := uint64(binary.LittleEndian.Uint32(header[4:])), uint64(binary.LittleEndian.Uint32(header[8:]))
+	start := uint64(offset) + 12
+	metaStart := start + ((size + 3) &^ 3)
+	end := metaStart + ((meta + 3) &^ 3)
+	if end > uint64(len(data)) {
+		return u3dBlock{}, 0, io.ErrUnexpectedEOF
+	}
+	for _, padding := range [][]byte{data[start+size : metaStart], data[metaStart+meta : end]} {
+		for _, value := range padding {
+			if value != 0 {
+				return u3dBlock{}, 0, fmt.Errorf("invalid U3D padding")
+			}
+		}
+	}
+	return u3dBlock{binary.LittleEndian.Uint32(header), data[start : start+size], data[metaStart : metaStart+meta]}, int(end), nil
+}
+
+// reserve 在分配解码数组前检查总预算及取消状态
+// 入参: count 元素数量, size 元素规模上界
+// 返回: error 预算或取消错误
+func (d *u3dDecoder) reserve(count, size uint64) error {
+	if err := d.ctx.Err(); err != nil {
+		return err
+	}
+	if size == 0 || count > d.remaining/size || count > uint64(^uint(0)>>1)/size {
+		return fmt.Errorf("U3D decoded data exceeds limit")
+	}
+	d.remaining -= count * size
+	return nil
+}
+
+// metadata 校验元数据结构并保留原始数据，不解释或执行其中的动作
+// 入参: block 数据块, name 所属资源名
+// 返回: error 结构、预算或取消错误
+func (d *u3dDecoder) metadata(block u3dBlock, name string) error {
+	if len(block.meta) == 0 {
+		return nil
+	}
+	if err := d.reserve(uint64(len(block.meta))+128, 1); err != nil {
+		return err
+	}
+	r := u3dValues{data: block.meta}
+	count := r.u32()
+	if uint64(count) > uint64(len(block.meta))/8 {
+		return fmt.Errorf("invalid U3D metadata count")
+	}
+	for range count {
+		if err := d.ctx.Err(); err != nil {
+			return err
+		}
+		flags := r.u32()
+		r.text()
+		if flags&1 != 0 {
+			size := r.u32()
+			if uint64(size) > uint64(len(r.data)-r.pos) {
+				return io.ErrUnexpectedEOF
+			}
+			r.take(int(size))
+		} else {
+			r.text()
+		}
+		if r.err != nil {
+			return r.err
+		}
+	}
+	if err := r.done(); err != nil {
+		return err
+	}
+	d.model.Metadata = append(d.model.Metadata, U3DMetadata{block.kind, name, bytes.Clone(block.meta)})
+	return nil
+}
+
+// chain 解析单层修饰链并校验名称、链类型与修饰顺序
+// 入参: block 修饰链块
+// 返回: error 结构、能力或资源错误
+func (d *u3dDecoder) chain(block u3dBlock) error {
+	if err := d.reserve(256, 1); err != nil {
+		return err
+	}
+	r := u3dValues{data: block.data}
+	name, kind, flags := r.text(), r.u32(), r.u32()
+	if kind > 2 || flags & ^uint32(3) != 0 {
+		return fmt.Errorf("invalid U3D modifier chain")
+	}
+	if flags&1 != 0 {
+		for range 4 {
+			r.f32()
+		}
+	}
+	if flags&2 != 0 {
+		for range 6 {
+			r.f32()
+		}
+	}
+	for r.pos%4 != 0 && r.err == nil {
+		if r.u8() != 0 {
+			return fmt.Errorf("invalid U3D chain padding")
+		}
+	}
+	count := r.u32()
+	if r.err != nil {
+		return r.err
+	}
+	if uint64(count) > uint64(len(r.data)-r.pos)/12 {
+		return fmt.Errorf("invalid U3D modifier count")
+	}
+	for index := uint32(0); index < count; index++ {
+		if err := d.ctx.Err(); err != nil {
+			return err
+		}
+		nested, next, err := u3dReadBlock(r.data, r.pos)
+		if err != nil {
+			return err
+		}
+		actual, err := d.block(nested, name, int(kind), index)
+		if err != nil {
+			return err
+		}
+		if actual != name {
+			return fmt.Errorf("U3D modifier name mismatch")
+		}
+		r.pos = next
+	}
+	if err := r.done(); err != nil {
+		return err
+	}
+	return d.metadata(block, name)
+}
+
+// block 解析支持的静态场景块，不丢弃未实现的修饰器或几何
+// 入参: block 数据块, owner 所属链名, chain 链类别，负值表示独立块, index 修饰位置
+// 返回: string 资源名, error 格式、能力或资源错误
+func (d *u3dDecoder) block(block u3dBlock, owner string, chain int, index uint32) (string, error) {
+	if err := d.ctx.Err(); err != nil {
+		return "", err
+	}
+	if err := d.reserve(uint64(len(block.data))+256, 1); err != nil {
+		return "", err
+	}
+	r := u3dValues{data: block.data}
+	name := r.text()
+	var err error
+	switch block.kind {
+	case 0xffffff21, 0xffffff22, 0xffffff23, 0xffffff24:
+		if chain >= 0 && (chain != 0 || index != 0) {
+			return name, fmt.Errorf("invalid U3D node chain")
+		}
+		err = d.node(&r, block.kind, name)
+	case 0xffffff31:
+		if chain >= 0 && (chain != 1 || index != 0) {
+			return name, fmt.Errorf("invalid U3D mesh chain")
+		}
+		err = d.meshDeclaration(&r, name)
+	case 0xffffff3b:
+		if chain >= 0 {
+			return name, fmt.Errorf("invalid U3D mesh continuation location")
+		}
+		err = d.baseMesh(&r, name)
+	case 0xffffff45:
+		if chain != 0 || index == 0 || owner != name || r.u32() != index {
+			return name, fmt.Errorf("invalid U3D shading modifier chain")
+		}
+		err = d.shading(&r, name)
+	case 0xffffff51, 0xffffff52, 0xffffff53, 0xffffff54:
+		if chain >= 0 {
+			return name, fmt.Errorf("invalid U3D palette resource location")
+		}
+		err = d.resource(&r, block.kind, name)
+	default:
+		return name, fmt.Errorf("unsupported U3D block %#x", block.kind)
+	}
+	if err != nil {
+		return name, err
+	}
+	if err := r.done(); err != nil {
+		return name, err
+	}
+	return name, d.metadata(block, name)
+}
+
+// node 读取节点与父变换，允许引用后续声明的父节点
+// 入参: r 字段读取器, kind 节点类型, name 节点名
+// 返回: error 结构或预算错误
+func (d *u3dDecoder) node(r *u3dValues, kind uint32, name string) error {
+	if _, exists := d.nodes[name]; exists {
+		return fmt.Errorf("duplicate U3D node %q", name)
+	}
+	node := U3DNode{Name: name, Kind: "Group"}
+	count := r.u32()
+	if uint64(count) > uint64(len(r.data)-r.pos)/66 {
+		return io.ErrUnexpectedEOF
+	}
+	if err := d.reserve(uint64(count), 96); err != nil {
+		return err
+	}
+	node.Parents = make([]U3DParent, int(count))
+	for index := range node.Parents {
+		if index%256 == 0 {
+			if err := d.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		node.Parents[index].Name = r.text()
+		for element := range node.Parents[index].Transform {
+			node.Parents[index].Transform[element] = r.f32()
+		}
+	}
+	if kind == 0xffffff22 {
+		node.Kind, node.Resource, node.Visibility = "Model", r.text(), r.u32()
+		if node.Visibility > 3 {
+			return fmt.Errorf("invalid U3D model visibility")
+		}
+	} else if kind == 0xffffff23 {
+		node.Kind, node.Resource = "Light", r.text()
+	} else if kind == 0xffffff24 {
+		node.Kind, node.Resource = "View", r.text()
+		var err error
+		node.View, err = d.view(r)
+		if err != nil {
+			return err
+		}
+	}
+	d.nodes[name] = len(d.model.Nodes)
+	d.model.Nodes = append(d.model.Nodes, node)
+	return r.err
+}
+
+// shading 读取网格着色列表，保留列表内各着色器的先后次序
+// 入参: r 字段读取器, name 目标节点名
+// 返回: error 结构、能力或预算错误
+func (d *u3dDecoder) shading(r *u3dValues, name string) error {
+	index, exists := d.nodes[name]
+	if !exists || d.model.Nodes[index].Kind != "Model" {
+		return fmt.Errorf("missing U3D shading target")
+	}
+	if r.u32() != 1 {
+		return fmt.Errorf("unsupported U3D non-mesh shading modifier")
+	}
+	count := r.u32()
+	if uint64(count) > uint64(len(r.data)-r.pos)/4 {
+		return io.ErrUnexpectedEOF
+	}
+	if err := d.reserve(uint64(count), 24); err != nil {
+		return err
+	}
+	lists := make([][]string, int(count))
+	for index := range lists {
+		n := r.u32()
+		if uint64(n) > uint64(len(r.data)-r.pos)/2 {
+			return io.ErrUnexpectedEOF
+		}
+		if err := d.reserve(uint64(n), 16); err != nil {
+			return err
+		}
+		lists[index] = make([]string, int(n))
+		for j := range lists[index] {
+			if j%256 == 0 {
+				if err := d.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			lists[index][j] = r.text()
+		}
+	}
+	d.model.Nodes[index].Shaders = lists
+	return r.err
+}
+
+// resource 读取独立材质、着色器、光源和视图资源
+// 入参: r 字段读取器, kind 资源类型, name 资源名
+// 返回: error 结构或能力错误
+func (d *u3dDecoder) resource(r *u3dValues, kind uint32, name string) error {
+	palette := d.palettes[kind]
+	if palette == nil {
+		palette = make(map[string]bool)
+		d.palettes[kind] = palette
+	}
+	if palette[name] {
+		return fmt.Errorf("duplicate U3D resource %q", name)
+	}
+	palette[name] = true
+	switch kind {
+	case 0xffffff52:
+		return d.viewResource(r, name)
+	case 0xffffff54:
+		material := U3DMaterial{Name: name, Attributes: r.u32()}
+		if material.Attributes & ^uint32(63) != 0 {
+			return fmt.Errorf("invalid U3D material attributes")
+		}
+		for _, color := range []*[3]float32{&material.Ambient, &material.Diffuse, &material.Specular, &material.Emissive} {
+			for index := range color {
+				color[index] = r.f32()
+			}
+		}
+		material.Reflectivity, material.Opacity = r.f32(), r.f32()
+		d.model.Materials = append(d.model.Materials, material)
+	case 0xffffff53:
+		shader := U3DShader{Name: name, Attributes: r.u32(), AlphaReference: r.f32(), AlphaFunction: r.u32(), Blend: r.u32(), RenderPass: r.u32()}
+		channels, alpha := r.u32(), r.u32()
+		shader.Material = r.text()
+		if shader.Attributes & ^uint32(7) != 0 || shader.AlphaFunction < 0x610 || shader.AlphaFunction > 0x617 || shader.Blend < 0x604 || shader.Blend > 0x607 || channels & ^uint32(255) != 0 || alpha & ^channels != 0 {
+			return fmt.Errorf("invalid U3D shader parameters")
+		}
+		if channels != 0 {
+			return fmt.Errorf("unsupported U3D textured shader")
+		}
+		d.model.Shaders = append(d.model.Shaders, shader)
+	case 0xffffff51:
+		light := U3DLight{Name: name, Attributes: r.u32(), Kind: r.u8()}
+		if light.Attributes & ^uint32(7) != 0 || light.Kind > 3 {
+			return fmt.Errorf("invalid U3D light parameters")
+		}
+		for index := range light.Color {
+			light.Color[index] = r.f32()
+		}
+		if r.f32() != 1 {
+			return fmt.Errorf("invalid U3D light reserved parameter")
+		}
+		for index := range light.Attenuation {
+			light.Attenuation[index] = r.f32()
+		}
+		light.SpotAngle, light.Intensity = r.f32(), r.f32()
+		d.model.Lights = append(d.model.Lights, light)
+	}
+	return r.err
+}
+
+// checkParents 迭代检查场景父子环路，不递归展开多父节点的实例组合
+// 返回: error 环路或取消错误
+func (d *u3dDecoder) checkParents() error {
+	state := make([]byte, len(d.model.Nodes))
+	type frame struct{ node, parent int }
+	var stack []frame
+	for index := range d.model.Nodes {
+		if state[index] != 0 {
+			continue
+		}
+		stack = append(stack[:0], frame{node: index})
+		state[index] = 1
+		for len(stack) != 0 {
+			if err := d.ctx.Err(); err != nil {
+				return err
+			}
+			current := &stack[len(stack)-1]
+			parents := d.model.Nodes[current.node].Parents
+			if current.parent == len(parents) {
+				state[current.node] = 2
+				stack = stack[:len(stack)-1]
+				continue
+			}
+			parent, exists := d.nodes[parents[current.parent].Name]
+			current.parent++
+			if !exists || state[parent] == 2 {
+				continue
+			}
+			if state[parent] == 1 {
+				return fmt.Errorf("cyclic U3D node parents")
+			}
+			state[parent] = 1
+			stack = append(stack, frame{node: parent})
+		}
+	}
+	return nil
+}

ofdgo_u3d_bits.go

@@ -0,0 +1,301 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"math"
+	"math/bits"
+	"unicode/utf8"
+)
+
+// u3dValues 读取U3D未压缩字段，不允许越过当前块
+type u3dValues struct {
+	data []byte
+	pos  int
+	err  error
+}
+
+// u3dBits 按ECMA-363第10章逆解16位算术区间，字节内按低位优先读取
+type u3dBits struct {
+	data            []byte
+	pos             uint64
+	low, high, code uint32
+	err             error
+}
+
+// u3dHistogram 保存一个动态压缩上下文的频次及前缀和
+type u3dHistogram struct {
+	counts []uint32
+	tree   []uint32
+	total  uint32
+}
+
+// take 读取定长字段，失败后不继续推进位置
+// 入参: size 字节数
+// 返回: []byte 字段数据，失败时为空
+func (r *u3dValues) take(size int) []byte {
+	if r.err != nil {
+		return nil
+	}
+	if size < 0 || size > len(r.data)-r.pos {
+		r.err = io.ErrUnexpectedEOF
+		return nil
+	}
+	value := r.data[r.pos : r.pos+size]
+	r.pos += size
+	return value
+}
+
+// u8 读取一个未压缩字节
+// 返回: byte 数值
+func (r *u3dValues) u8() byte {
+	value := r.take(1)
+	if value == nil {
+		return 0
+	}
+	return value[0]
+}
+
+// u32 读取小端32位整数
+// 返回: uint32 数值
+func (r *u3dValues) u32() uint32 {
+	value := r.take(4)
+	if value == nil {
+		return 0
+	}
+	return binary.LittleEndian.Uint32(value)
+}
+
+// f32 读取有限单精度数值
+// 返回: float32 数值
+func (r *u3dValues) f32() float32 {
+	value := math.Float32frombits(r.u32())
+	if !finite(float64(value)) && r.err == nil {
+		r.err = fmt.Errorf("invalid U3D floating-point value")
+	}
+	return value
+}
+
+// text 读取带16位字节长度的UTF-8字符串
+// 返回: string 文本
+func (r *u3dValues) text() string {
+	length := r.take(2)
+	if length == nil {
+		return ""
+	}
+	data := r.take(int(binary.LittleEndian.Uint16(length)))
+	if r.err == nil && !utf8.Valid(data) {
+		r.err = fmt.Errorf("invalid U3D UTF-8 string")
+	}
+	return string(data)
+}
+
+// done 检查字段是否恰好覆盖当前块
+// 返回: error 读取或多余字段错误
+func (r *u3dValues) done() error {
+	if r.err != nil {
+		return r.err
+	}
+	if r.pos != len(r.data) {
+		return fmt.Errorf("unexpected U3D block data")
+	}
+	return nil
+}
+
+// newU3DBits 初始化当前块的独立算术解码状态
+// 入参: data 块数据
+// 返回: *u3dBits 解码器
+func newU3DBits(data []byte) *u3dBits {
+	r := &u3dBits{data: data, high: 0xffff}
+	for range 16 {
+		r.code = r.code<<1 | r.bit()
+	}
+	return r
+}
+
+// bit 读取低位优先比特，区间预读最多允许16个末尾零位
+// 返回: uint32 比特
+func (r *u3dBits) bit() uint32 {
+	if r.err != nil {
+		return 0
+	}
+	limit := uint64(len(r.data)) * 8
+	var value uint32
+	if r.pos < limit {
+		value = uint32(r.data[r.pos/8]>>(r.pos%8)) & 1
+	} else if r.pos >= limit+16 {
+		r.err = io.ErrUnexpectedEOF
+		return 0
+	}
+	r.pos++
+	return value
+}
+
+// cumulative 求当前编码值在上下文累计频次中的位置
+// 入参: total 总频次
+// 返回: uint32 累计频次位置
+func (r *u3dBits) cumulative(total uint32) uint32 {
+	if r.err != nil {
+		return 0
+	}
+	if total == 0 || r.code < r.low || r.code > r.high {
+		r.err = fmt.Errorf("invalid U3D arithmetic interval")
+		return 0
+	}
+	return uint32((uint64(r.code-r.low+1)*uint64(total) - 1) / uint64(r.high-r.low+1))
+}
+
+// advance 收缩符号区间并执行同位及下溢归一化
+// 入参: start 累计频次, count 符号频次, total 总频次
+func (r *u3dBits) advance(start, count, total uint32) {
+	if r.err != nil {
+		return
+	}
+	if count == 0 || start >= total || count > total-start {
+		r.err = fmt.Errorf("invalid U3D symbol frequency")
+		return
+	}
+	width := uint64(r.high-r.low) + 1
+	r.high = r.low + uint32(width*uint64(start+count)/uint64(total)) - 1
+	r.low += uint32(width * uint64(start) / uint64(total))
+	for r.err == nil {
+		var offset uint32
+		switch {
+		case r.high < 0x8000:
+		case r.low >= 0x8000:
+			offset = 0x8000
+		case r.low >= 0x4000 && r.high < 0xc000:
+			offset = 0x4000
+		default:
+			return
+		}
+		r.low = (r.low - offset) << 1
+		r.high = (r.high-offset)<<1 | 1
+		r.code = (r.code-offset)<<1 | r.bit()
+	}
+}
+
+// byteValue 逆解静态256符号上下文中的反序字节
+// 返回: byte 原始字节
+func (r *u3dBits) byteValue() byte {
+	value := r.cumulative(256)
+	r.advance(value, 1, 256)
+	return bits.Reverse8(byte(value))
+}
+
+// u32 逆解四个小端字节，不重置压缩区间
+// 返回: uint32 原始整数
+func (r *u3dBits) u32() uint32 {
+	var value uint32
+	for shift := range 4 {
+		value |= uint32(r.byteValue()) << (8 * shift)
+	}
+	return value
+}
+
+// index 读取静态上下文的网格索引，大范围按标准使用未压缩整数
+// 入参: count 索引范围
+// 返回: uint32 索引
+func (r *u3dBits) index(count uint32) uint32 {
+	if count > 0x3ffe {
+		return r.u32()
+	}
+	value := r.cumulative(count)
+	r.advance(value, 1, count)
+	return value
+}
+
+// dynamic 读取动态上下文数值，逃逸后的字面量仍使用当前算术区间
+// 入参: h 频次上下文
+// 返回: uint32 原始整数
+func (r *u3dBits) dynamic(h *u3dHistogram) uint32 {
+	if h.total == 0 {
+		h.counts = make([]uint32, 1)
+		h.tree = make([]uint32, 2)
+		h.add(0)
+	}
+	index := r.cumulative(h.total)
+	symbol, start := h.find(index)
+	if r.err != nil {
+		return 0
+	}
+	r.advance(start, h.counts[symbol], h.total)
+	h.add(symbol)
+	if symbol != 0 {
+		return symbol - 1
+	}
+	value := r.u32()
+	if value < 0xffff && r.err == nil {
+		h.add(value + 1)
+	}
+	return value
+}
+
+// find 以树状前缀和定位符号，避免按符号数量线性扫描
+// 入参: position 累计频次位置
+// 返回: uint32 符号, uint32 符号前缀频次
+func (h *u3dHistogram) find(position uint32) (uint32, uint32) {
+	index, prefix := 0, uint32(0)
+	for step := 1 << (bits.Len(uint(len(h.tree))) - 1); step != 0; step >>= 1 {
+		next := index + step
+		if next < len(h.tree) && h.tree[next] <= position-prefix {
+			prefix += h.tree[next]
+			index = next
+		}
+	}
+	return uint32(index), prefix
+}
+
+// add 更新动态频次，并按ECMA-363阈值缩减历史频次
+// 入参: symbol 符号，超过16位的值不加入上下文
+func (h *u3dHistogram) add(symbol uint32) {
+	if symbol > 0xffff {
+		return
+	}
+	if h.total >= 0x1fff {
+		for index := range h.counts {
+			h.counts[index] >>= 1
+		}
+		h.counts[0]++
+		h.rebuild()
+	}
+	if int(symbol) >= len(h.counts) {
+		length := min(65536, max(int(symbol)+1, len(h.counts)*2))
+		h.counts = append(h.counts, make([]uint32, length-len(h.counts))...)
+		h.rebuild()
+	}
+	h.counts[symbol]++
+	h.total++
+	for index := int(symbol) + 1; index < len(h.tree); index += index & -index {
+		h.tree[index]++
+	}
+}
+
+// rebuild 在线性时间内重建动态频次索引
+func (h *u3dHistogram) rebuild() {
+	h.tree = make([]uint32, len(h.counts)+1)
+	h.total = 0
+	for index, count := range h.counts {
+		h.total += count
+		i := index + 1
+		h.tree[i] += count
+		if next := i + (i & -i); next < len(h.tree) {
+			h.tree[next] += h.tree[i]
+		}
+	}
+}

ofdgo_u3d_light.go

@@ -0,0 +1,326 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+)
+
+// U3DDirectionalLight 定义无限远光源，Direction为发射方向，CameraRelative使用相机坐标
+type U3DDirectionalLight struct {
+	Color, Direction [3]float64
+	CameraRelative   bool
+}
+
+// U3DLighting 替换场景灯光，空灯光列表表示无光源，DiffuseOffset加到受光材质的漫反射颜色
+// 颜色及漫反射增量的各分量取值为0到1；不修改材质自发光或不受光着色器
+type U3DLighting struct {
+	Lights        []U3DDirectionalLight
+	DiffuseOffset [3]float64
+}
+
+// u3dRenderLight 保存世界空间的光源位置与正Z发射方向
+type u3dRenderLight struct {
+	value               U3DLight
+	position, direction u3dVector
+}
+
+// u3dRenderStyle 保存当前着色器的有效材质参数
+type u3dRenderStyle struct {
+	shader                               U3DShader
+	ambient, diffuse, specular, emissive [3]float64
+	opacity, exponent                    float64
+}
+
+// collectLights 收集本轮根节点下启用的光源实例
+// 返回: error 参数、预算或取消错误
+func (r *u3dRender) collectLights() error {
+	if r.lighting != nil {
+		return nil
+	}
+	r.lights = r.lights[:0]
+	for i, instance := range r.scene {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		node := r.model.Nodes[instance.node]
+		if !r.members[i] || node.Kind != "Light" {
+			continue
+		}
+		j, ok := r.lightIndex[node.Resource]
+		if !ok {
+			continue
+		}
+		light := r.model.Lights[j]
+		if light.Attributes&1 == 0 {
+			continue
+		}
+		if light.Attributes > 7 || light.Kind > 3 {
+			return fmt.Errorf("invalid U3D light")
+		}
+		for _, v := range light.Color {
+			if !finite(float64(v)) {
+				return fmt.Errorf("invalid U3D light color")
+			}
+		}
+		if light.Kind != 0 && !finite(float64(light.Intensity)) {
+			return fmt.Errorf("invalid U3D light intensity")
+		}
+		if light.Kind >= 2 {
+			for _, v := range light.Attenuation {
+				if !finite(float64(v)) {
+					return fmt.Errorf("invalid U3D light attenuation")
+				}
+			}
+		}
+		if light.Kind == 3 && (!finite(float64(light.SpotAngle)) || light.SpotAngle <= 0 || light.SpotAngle > 180) {
+			return fmt.Errorf("invalid U3D spot angle")
+		}
+		world := instance.world
+		item := u3dRenderLight{value: light, position: u3dVector{world[12], world[13], world[14]}, direction: (u3dVector{world[8], world[9], world[10]}).unit()}
+		if (light.Kind == 1 || light.Kind == 3) && item.direction == (u3dVector{}) {
+			return fmt.Errorf("invalid U3D light direction")
+		}
+		if len(r.lights) == cap(r.lights) {
+			capacity := max(8, cap(r.lights)*2)
+			if err := r.reserve(uint64(capacity), 128); err != nil {
+				return err
+			}
+			values := make([]u3dRenderLight, len(r.lights), capacity)
+			copy(values, r.lights)
+			r.remaining += uint64(cap(r.lights)) * 128
+			r.lights = values
+		}
+		r.lights = append(r.lights, item)
+	}
+	return nil
+}
+
+// overrideLighting 校验并建立替代光源，不依赖模型光源节点
+// 入参: lighting 灯光覆盖，空值保留模型灯光
+// 返回: error 参数、预算或取消错误
+func (r *u3dRender) overrideLighting(lighting *U3DLighting) error {
+	if lighting == nil {
+		return nil
+	}
+	for _, v := range lighting.DiffuseOffset {
+		if !finite(v) || v < 0 || v > 1 {
+			return fmt.Errorf("invalid U3D diffuse offset")
+		}
+	}
+	if err := r.reserve(uint64(len(lighting.Lights)), 128); err != nil {
+		return err
+	}
+	r.lights = make([]u3dRenderLight, len(lighting.Lights))
+	for i, light := range lighting.Lights {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		for j, v := range light.Color {
+			if !finite(v) || v < 0 || v > 1 || !finite(light.Direction[j]) {
+				return fmt.Errorf("invalid U3D directional light")
+			}
+		}
+		direction := u3dVector(light.Direction).unit()
+		if light.CameraRelative && r.camera.ToWorld != ([16]float64{}) {
+			m := r.camera.ToWorld
+			direction = u3dVector{m[0]*direction[0] + m[4]*direction[1] + m[8]*direction[2], m[1]*direction[0] + m[5]*direction[1] + m[9]*direction[2], m[2]*direction[0] + m[6]*direction[1] + m[10]*direction[2]}.unit()
+		}
+		if direction == (u3dVector{}) {
+			return fmt.Errorf("invalid U3D directional light direction")
+		}
+		r.lights[i] = u3dRenderLight{value: U3DLight{Attributes: 3, Kind: 1, Intensity: 1}, direction: direction}
+	}
+	r.lighting = lighting
+	return nil
+}
+
+// style 解析着色器与材质，未启用的材质项使用固定默认值
+// 入参: name 着色器名
+// 返回: u3dRenderStyle 有效绘制参数, error 参数错误
+func (r *u3dRender) style(name string) (u3dRenderStyle, error) {
+	style := u3dRenderStyle{shader: U3DShader{Blend: 0x606, AlphaFunction: 0x617, RenderPass: math.MaxUint32}, ambient: [3]float64{.2, .2, .2}, diffuse: [3]float64{.8, .8, .8}, opacity: 1}
+	if index, ok := r.shaders[name]; ok {
+		style.shader = r.model.Shaders[index]
+	}
+	shader := style.shader
+	if shader.Attributes > 7 || shader.Blend < 0x604 || shader.Blend > 0x607 || shader.AlphaFunction < 0x610 || shader.AlphaFunction > 0x617 || shader.Attributes&2 != 0 && !finite(float64(shader.AlphaReference)) {
+		return style, fmt.Errorf("invalid U3D render shader")
+	}
+	if index, ok := r.materials[shader.Material]; ok {
+		material := r.model.Materials[index]
+		if material.Attributes > 63 {
+			return style, fmt.Errorf("invalid U3D render material")
+		}
+		for i, item := range []struct {
+			source [3]float32
+			target *[3]float64
+		}{{material.Ambient, &style.ambient}, {material.Diffuse, &style.diffuse}, {material.Specular, &style.specular}, {material.Emissive, &style.emissive}} {
+			if material.Attributes&(1<<i) != 0 {
+				for j, v := range item.source {
+					if !finite(float64(v)) {
+						return style, fmt.Errorf("invalid U3D material color")
+					}
+					item.target[j] = float64(v)
+				}
+			}
+		}
+		if material.Attributes&16 != 0 {
+			if !finite(float64(material.Reflectivity)) {
+				return style, fmt.Errorf("invalid U3D reflectivity")
+			}
+			style.exponent = min(1, max(0, float64(material.Reflectivity))) * 128
+		}
+		if material.Attributes&32 != 0 {
+			if !finite(float64(material.Opacity)) {
+				return style, fmt.Errorf("invalid U3D opacity")
+			}
+			style.opacity = min(1, max(0, float64(material.Opacity)))
+		}
+	}
+	return style, nil
+}
+
+// shade 按世界坐标计算逐顶点漫反射、镜面与环境光
+// 入参: position 顶点, normal 法线, style 材质, diffuse 顶点漫反射, specular 顶点镜面颜色
+// 返回: [4]float64 直通RGBA, error 参数或取消错误
+func (r *u3dRender) shade(position, normal u3dVector, style u3dRenderStyle, diffuse, specular *[4]float32) ([4]float64, error) {
+	color := [4]float64{style.diffuse[0], style.diffuse[1], style.diffuse[2], style.opacity}
+	if style.shader.Attributes&4 != 0 {
+		if diffuse != nil {
+			for i, v := range diffuse {
+				if !finite(float64(v)) {
+					return color, fmt.Errorf("invalid U3D vertex color")
+				}
+				if i < 3 {
+					color[i] = float64(v)
+					style.diffuse[i] = float64(v)
+					style.ambient[i] = float64(v)
+				} else {
+					color[3] *= min(1, max(0, float64(v)))
+				}
+			}
+		}
+		if specular != nil {
+			for i, v := range specular[:3] {
+				if !finite(float64(v)) {
+					return color, fmt.Errorf("invalid U3D vertex specular color")
+				}
+				style.specular[i] = float64(v)
+			}
+		}
+	}
+	if style.shader.Attributes&1 == 0 {
+		return color, nil
+	}
+	if r.lighting != nil {
+		for c := range 3 {
+			style.diffuse[c] += r.lighting.DiffuseOffset[c]
+		}
+	}
+	copy(color[:3], style.emissive[:])
+	eye := (u3dVector{r.camera.ToWorld[12], r.camera.ToWorld[13], r.camera.ToWorld[14]}).sub(position).unit()
+	if !r.camera.Perspective {
+		eye = (u3dVector{-r.camera.ToWorld[8], -r.camera.ToWorld[9], -r.camera.ToWorld[10]}).unit()
+		if r.camera.ToWorld == ([16]float64{}) {
+			eye = u3dVector{0, 0, -1}
+		}
+	}
+	for i, light := range r.lights {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return color, err
+			}
+		}
+		value := light.value
+		if value.Kind == 0 {
+			for c := range 3 {
+				color[c] += style.ambient[c] * float64(value.Color[c])
+			}
+			continue
+		}
+		incoming := u3dVector{-light.direction[0], -light.direction[1], -light.direction[2]}
+		factor := float64(value.Intensity)
+		if value.Kind >= 2 {
+			incoming = light.position.sub(position)
+			distance := math.Hypot(math.Hypot(incoming[0], incoming[1]), incoming[2])
+			denominator := float64(value.Attenuation[0]) + float64(value.Attenuation[1])*distance + float64(value.Attenuation[2])*distance*distance
+			if !finite(denominator) || denominator == 0 {
+				return color, fmt.Errorf("invalid U3D point attenuation")
+			}
+			factor /= denominator
+			incoming = incoming.unit()
+			if value.Kind == 3 {
+				cosine := -incoming.dot(light.direction)
+				cutoff := math.Cos(float64(value.SpotAngle) * math.Pi / 360)
+				if cosine < cutoff {
+					continue
+				}
+				if value.Attributes&4 != 0 && cutoff < 1 {
+					factor *= min(1, max(0, (cosine-cutoff)/(1-cutoff)))
+				}
+			}
+		}
+		diffuseAmount := max(0, normal.dot(incoming))
+		specularAmount := 0.0
+		if diffuseAmount > 0 && style.exponent > 0 && value.Attributes&2 != 0 {
+			reflection := u3dVector{2*diffuseAmount*normal[0] - incoming[0], 2*diffuseAmount*normal[1] - incoming[1], 2*diffuseAmount*normal[2] - incoming[2]}
+			specularAmount = math.Pow(max(0, reflection.dot(eye)), style.exponent)
+		}
+		for c := range 3 {
+			lightColor := float64(value.Color[c])
+			if r.lighting != nil {
+				lightColor = r.lighting.Lights[i].Color[c]
+			}
+			color[c] += lightColor * factor * (style.diffuse[c]*diffuseAmount + style.specular[c]*specularAmount)
+		}
+	}
+	for _, v := range color {
+		if !finite(v) {
+			return color, fmt.Errorf("invalid U3D lighting result")
+		}
+	}
+	return color, nil
+}
+
+// u3dAlphaTest 按ECMA-363枚举比较透明度，不套用图形接口的枚举顺序
+// 入参: function 比较函数, value 透明度, reference 参考值
+// 返回: bool 是否通过
+func u3dAlphaTest(function uint32, value, reference float64) bool {
+	switch function {
+	case 0x610:
+		return false
+	case 0x611:
+		return value < reference
+	case 0x612:
+		return value > reference
+	case 0x613:
+		return value == reference
+	case 0x614:
+		return value != reference
+	case 0x615:
+		return value <= reference
+	case 0x616:
+		return value >= reference
+	case 0x617:
+		return true
+	}
+	return false
+}

ofdgo_u3d_line.go

@@ -0,0 +1,231 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+)
+
+// frustumPlanes 返回保留正侧的六个相机视锥面
+// 返回: [6][4]float64 近、远、左右及上下平面
+func (r *u3dRender) frustumPlanes() [6][4]float64 {
+	w, h := r.viewport[2]/2, r.viewport[3]/2
+	planes := [6][4]float64{{0, 0, 1, -r.camera.Near}, {0, 0, -1, r.camera.Far}, {r.camera.ScaleX, 0, 0, w + r.camera.ShiftX}, {-r.camera.ScaleX, 0, 0, w - r.camera.ShiftX}, {0, r.camera.ScaleY, 0, h - r.camera.ShiftY}, {0, -r.camera.ScaleY, 0, h + r.camera.ShiftY}}
+	if r.camera.Perspective {
+		for i := 2; i < 6; i++ {
+			planes[i][2], planes[i][3] = planes[i][3], 0
+		}
+	}
+	return planes
+}
+
+// u3dPlaneDistance 计算未归一化的平面有符号距离
+// 入参: plane 平面方程, point 点坐标
+// 返回: float64 有符号距离
+func u3dPlaneDistance(plane [4]float64, point u3dVector) float64 {
+	return plane[0]*point[0] + plane[1]*point[1] + plane[2]*point[2] + plane[3]
+}
+
+// u3dClipFraction 计算异侧有限距离的交点比例，避免绝对值求和溢出
+// 入参: a 起点距离, b 终点距离
+// 返回: float64 插值比例
+func u3dClipFraction(a, b float64) float64 {
+	a, b = math.Abs(a), math.Abs(b)
+	scale := max(a, b)
+	if scale == 0 {
+		return 0
+	}
+	a, b = a/scale, b/scale
+	return a / (a + b)
+}
+
+// u3dInterpolate 在相机空间插值坐标与未预乘颜色
+// 入参: a 起点, b 终点, t 比例
+// 返回: u3dVertex 插值顶点
+func u3dInterpolate(a, b u3dVertex, t float64) u3dVertex {
+	var result u3dVertex
+	for i := range result.point {
+		result.point[i] = a.point[i]*(1-t) + b.point[i]*t
+	}
+	for i := range result.color {
+		result.color[i] = a.color[i]*(1-t) + b.color[i]*t
+	}
+	return result
+}
+
+// sectionIntersection 绘制原三角面与指定剖切面的交线，其他剖切面仍参与裁剪
+// 入参: triangle 原三角面, index 剖切面索引
+// 返回: error 数值、资源或取消错误
+func (r *u3dRender) sectionIntersection(triangle [3]u3dVertex, index int) error {
+	if err := r.ctx.Err(); err != nil {
+		return err
+	}
+	section := r.sections[index]
+	var distances [3]float64
+	for i, vertex := range triangle {
+		distances[i] = u3dPlaneDistance(section.plane, vertex.point)
+		if !finite(distances[i]) {
+			return fmt.Errorf("invalid U3D intersection distance")
+		}
+	}
+	if distances == ([3]float64{}) {
+		return nil
+	}
+	var points [3]u3dVertex
+	count := 0
+	add := func(vertex u3dVertex) {
+		for i := range count {
+			if points[i].point == vertex.point {
+				return
+			}
+		}
+		if count < len(points) {
+			points[count], count = vertex, count+1
+		}
+	}
+	for i, vertex := range triangle {
+		j := (i + 1) % 3
+		if distances[i] == 0 {
+			add(vertex)
+		}
+		if distances[i] < 0 && distances[j] > 0 || distances[i] > 0 && distances[j] < 0 {
+			add(u3dInterpolate(vertex, triangle[j], u3dClipFraction(distances[i], distances[j])))
+		}
+	}
+	if count < 2 {
+		return nil
+	}
+	a, b := points[0], points[1]
+	for i, other := range r.sections {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if i != index {
+			keep, err := u3dClipLine(&a, &b, other.plane)
+			if err != nil || !keep {
+				return err
+			}
+		}
+	}
+	for i, plane := range r.frustumPlanes() {
+		if i == 1 && r.camera.Far == 0 && !r.camera.ClipFar {
+			continue
+		}
+		keep, err := u3dClipLine(&a, &b, plane)
+		if err != nil || !keep {
+			return err
+		}
+	}
+	normal := u3dTriangleNormal([3]u3dVector{triangle[0].point, triangle[1].point, triangle[2].point})
+	return r.rasterSectionLine(a, b, *section.intersection, normal, triangle[0].point)
+}
+
+// u3dClipLine 将线段裁至平面正侧
+// 入参: a 起点, b 终点, plane 平面方程
+// 返回: bool 是否保留, error 数值错误
+func u3dClipLine(a, b *u3dVertex, plane [4]float64) (bool, error) {
+	da, db := u3dPlaneDistance(plane, a.point), u3dPlaneDistance(plane, b.point)
+	if !finite(da) || !finite(db) {
+		return false, fmt.Errorf("invalid U3D line clip distance")
+	}
+	if da < 0 && db < 0 {
+		return false, nil
+	}
+	if (da < 0) != (db < 0) {
+		intersection := u3dInterpolate(*a, *b, u3dClipFraction(da, db))
+		if da < 0 {
+			*a = intersection
+		} else {
+			*b = intersection
+		}
+	}
+	return true, nil
+}
+
+// rasterSectionLine 绘制单像素不透明交线，透视深度使用倒数插值
+// 入参: a 已裁剪起点, b 已裁剪终点, rgb 交线颜色, normal 原面法线, origin 原面上一点
+// 返回: error 数值、资源或取消错误
+func (r *u3dRender) rasterSectionLine(a, b u3dVertex, rgb [3]float64, normal, origin u3dVector) error {
+	cx := r.viewport[0] + r.viewport[2]/2 + r.camera.ShiftX
+	cy := r.viewport[1] + r.viewport[3]/2 + r.camera.ShiftY
+	planes := [4][4]float64{{r.camera.ScaleX, 0, 0, cx}, {-r.camera.ScaleX, 0, 0, float64(r.output.Rect.Dx()) - cx}, {0, -r.camera.ScaleY, 0, cy}, {0, r.camera.ScaleY, 0, float64(r.output.Rect.Dy()) - cy}}
+	for _, plane := range planes {
+		if r.camera.Perspective {
+			plane[2], plane[3] = plane[3], 0
+		}
+		keep, err := u3dClipLine(&a, &b, plane)
+		if err != nil || !keep {
+			return err
+		}
+	}
+	var x, y, q [2]float64
+	for i, vertex := range [2]u3dVertex{a, b} {
+		q[i] = 1
+		if r.camera.Perspective {
+			if vertex.point[2] <= 0 {
+				return fmt.Errorf("invalid U3D line perspective depth")
+			}
+			q[i] = 1 / vertex.point[2]
+		}
+		x[i] = cx + vertex.point[0]*r.camera.ScaleX*q[i]
+		y[i] = cy - vertex.point[1]*r.camera.ScaleY*q[i]
+		if !finite(x[i]) || !finite(y[i]) || !finite(q[i]) {
+			return fmt.Errorf("invalid U3D projected line")
+		}
+	}
+	steps := math.Ceil(max(math.Abs(x[1]-x[0]), math.Abs(y[1]-y[0])))
+	if !finite(steps) || steps > float64(max(r.output.Rect.Dx(), r.output.Rect.Dy()))+2 {
+		return fmt.Errorf("invalid U3D line span")
+	}
+	count := max(1, int(steps))
+	color := [4]float64{rgb[0], rgb[1], rgb[2], 1}
+	r.order++
+	for i := 0; i <= count; i++ {
+		if i%1024 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		t := float64(i) / float64(count)
+		px, py := math.Floor(x[0]*(1-t)+x[1]*t), math.Floor(y[0]*(1-t)+y[1]*t)
+		if px < 0 || py < 0 || px >= float64(r.output.Rect.Dx()) || py >= float64(r.output.Rect.Dy()) {
+			continue
+		}
+		depth := a.point[2]*(1-t) + b.point[2]*t
+		if r.camera.Perspective {
+			depth = 1 / (q[0]*(1-t) + q[1]*t)
+		}
+		ray := u3dVector{(px + .5 - cx) / r.camera.ScaleX, (cy - py - .5) / r.camera.ScaleY, 1}
+		denominator := normal[2]
+		numerator := normal.dot(origin) - normal[0]*ray[0] - normal[1]*ray[1]
+		if r.camera.Perspective {
+			denominator, numerator = normal.dot(ray), normal.dot(origin)
+		}
+		if sampled := numerator / denominator; finite(sampled) && sampled >= r.camera.Near && (r.camera.Far == 0 && !r.camera.ClipFar || sampled <= r.camera.Far) {
+			depth = sampled
+		}
+		depth -= 8 * math.Abs(depth-math.Nextafter(depth, math.Inf(-1)))
+		pixel := int(py)*r.output.Rect.Dx() + int(px)
+		if depth <= r.frame[pixel].depth {
+			if err := r.fragment(pixel, depth, color, 0x606); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}

ofdgo_u3d_mesh.go

@@ -0,0 +1,295 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"io"
+)
+
+// U3DMesh 保存完整基础网格的独立数组，索引对应原始作者网格
+type U3DMesh struct {
+	Name                                        string
+	ExcludeNormals                              bool
+	Positions, Normals                          [][3]float32
+	Diffuse, Specular, TextureCoordinates       [][4]float32
+	Shadings                                    []U3DShading
+	Faces                                       []U3DFace
+	Quality                                     [3]uint32
+	InverseQuantization                         [5]float32
+	NormalCrease, NormalUpdate, NormalTolerance float32
+}
+
+// U3DShading 描述各面使用的颜色及纹理坐标，纹理维数依层排列
+type U3DShading struct {
+	Attributes        uint32
+	TextureDimensions []uint32
+	OriginalID        uint32
+}
+
+// U3DFace 保存着色描述索引和依原始绕序排列的三个角点
+type U3DFace struct {
+	Shading uint32
+	Corners [3]U3DCorner
+}
+
+// U3DCorner 保存各属性索引，未启用的属性不可用于访问数组
+type U3DCorner struct {
+	Position, Normal, Diffuse, Specular uint32
+	Texture                             [8]uint32
+}
+
+// u3dMeshDeclaration 保存基础网格声明及续块接收状态
+type u3dMeshDeclaration struct {
+	mesh    U3DMesh
+	counts  [7]uint32
+	decoded bool
+}
+
+// meshDeclaration 读取完整基础网格声明，不将渐进网格当作完整模型
+// 入参: r 字段读取器, name 网格名
+// 返回: error 结构、能力或预算错误
+func (d *u3dDecoder) meshDeclaration(r *u3dValues, name string) error {
+	if _, exists := d.meshes[name]; exists {
+		return fmt.Errorf("duplicate U3D mesh %q", name)
+	}
+	index, attributes := r.u32(), r.u32()
+	if index != 0 || attributes > 1 {
+		return fmt.Errorf("invalid U3D mesh declaration")
+	}
+	decl := &u3dMeshDeclaration{mesh: U3DMesh{Name: name, ExcludeNormals: attributes == 1}}
+	for index := range decl.counts {
+		decl.counts[index] = r.u32()
+	}
+	count := decl.counts[6]
+	if uint64(count) > uint64(len(r.data)-r.pos)/12 {
+		return io.ErrUnexpectedEOF
+	}
+	if err := d.reserve(uint64(count), 40); err != nil {
+		return err
+	}
+	decl.mesh.Shadings = make([]U3DShading, int(count))
+	for index := range decl.mesh.Shadings {
+		shading := &decl.mesh.Shadings[index]
+		shading.Attributes = r.u32()
+		layers := r.u32()
+		if shading.Attributes > 3 {
+			return fmt.Errorf("invalid U3D shading attributes")
+		}
+		if layers > 8 {
+			return fmt.Errorf("unsupported U3D texture layer count")
+		}
+		if err := d.reserve(uint64(layers), 4); err != nil {
+			return err
+		}
+		shading.TextureDimensions = make([]uint32, int(layers))
+		for layer := range shading.TextureDimensions {
+			dimension := r.u32()
+			if dimension < 1 || dimension > 4 {
+				return fmt.Errorf("invalid U3D texture coordinate dimension")
+			}
+			shading.TextureDimensions[layer] = dimension
+		}
+		shading.OriginalID = r.u32()
+	}
+	minimum, maximum := r.u32(), r.u32()
+	for index := range decl.mesh.Quality {
+		decl.mesh.Quality[index] = r.u32()
+	}
+	for index := range decl.mesh.InverseQuantization {
+		decl.mesh.InverseQuantization[index] = r.f32()
+	}
+	decl.mesh.NormalCrease, decl.mesh.NormalUpdate, decl.mesh.NormalTolerance = r.f32(), r.f32(), r.f32()
+	bones := r.u32()
+	if r.err != nil {
+		return r.err
+	}
+	if minimum > maximum || maximum != decl.counts[1] {
+		return fmt.Errorf("invalid U3D mesh resolution")
+	}
+	if minimum != maximum || bones != 0 {
+		return fmt.Errorf("unsupported U3D progressive or skeletal mesh")
+	}
+	if minimum == 0 {
+		for _, count := range decl.counts[:6] {
+			if count != 0 {
+				return fmt.Errorf("invalid U3D empty mesh")
+			}
+		}
+	}
+	d.meshes[name] = decl
+	d.meshOrder = append(d.meshOrder, name)
+	return nil
+}
+
+// baseMesh 读取基础顶点与压缩面索引，保留各角点的独立属性
+// 入参: r 字段读取器, name 网格名
+// 返回: error 结构、能力、预算或取消错误
+func (d *u3dDecoder) baseMesh(r *u3dValues, name string) error {
+	decl := d.meshes[name]
+	if decl == nil || decl.decoded || decl.counts[1] == 0 || r.u32() != 0 {
+		return fmt.Errorf("invalid U3D base mesh reference")
+	}
+	var counts [6]uint32
+	for index := range counts {
+		counts[index] = r.u32()
+		if counts[index] != decl.counts[index] {
+			return fmt.Errorf("U3D base mesh does not match full resolution declaration")
+		}
+	}
+	if r.err != nil {
+		return r.err
+	}
+	literalBytes := (uint64(counts[1])+uint64(counts[2]))*12 + (uint64(counts[3])+uint64(counts[4])+uint64(counts[5]))*16
+	if literalBytes > uint64(len(r.data)-r.pos) {
+		return io.ErrUnexpectedEOF
+	}
+	if err := d.reserve(literalBytes, 1); err != nil {
+		return err
+	}
+	if err := d.reserve(uint64(counts[0]), 148); err != nil {
+		return err
+	}
+	mesh := &decl.mesh
+	mesh.Positions, mesh.Normals = make([][3]float32, int(counts[1])), make([][3]float32, int(counts[2]))
+	mesh.Diffuse, mesh.Specular, mesh.TextureCoordinates = make([][4]float32, int(counts[3])), make([][4]float32, int(counts[4])), make([][4]float32, int(counts[5]))
+	for _, array := range [][][3]float32{mesh.Positions, mesh.Normals} {
+		for index := range array {
+			if index%1024 == 0 {
+				if r.err != nil {
+					return r.err
+				}
+				if err := d.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			for component := range array[index] {
+				array[index][component] = r.f32()
+			}
+		}
+	}
+	for _, array := range [][][4]float32{mesh.Diffuse, mesh.Specular, mesh.TextureCoordinates} {
+		for index := range array {
+			if index%1024 == 0 {
+				if r.err != nil {
+					return r.err
+				}
+				if err := d.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			for component := range array[index] {
+				array[index][component] = r.f32()
+			}
+		}
+	}
+	if r.err != nil {
+		return r.err
+	}
+	mesh.Faces = make([]U3DFace, int(counts[0]))
+	var histogram u3dHistogram
+	var compressed *u3dBits
+	if !d.plain && counts[0] != 0 {
+		if err := d.reserve(1, 1<<20); err != nil {
+			return err
+		}
+		compressed = newU3DBits(r.data[r.pos:])
+	}
+	readIndex := func(count uint32) (uint32, error) {
+		var value uint32
+		if compressed == nil {
+			value = r.u32()
+		} else {
+			value = compressed.index(count)
+			if compressed.err != nil {
+				return 0, compressed.err
+			}
+		}
+		if r.err != nil {
+			return 0, r.err
+		}
+		if value >= count {
+			return 0, fmt.Errorf("invalid U3D corner index")
+		}
+		return value, nil
+	}
+	for index := range mesh.Faces {
+		if index%256 == 0 {
+			if err := d.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		face := &mesh.Faces[index]
+		if compressed == nil {
+			face.Shading = r.u32()
+		} else {
+			face.Shading = compressed.dynamic(&histogram)
+			if compressed.err != nil {
+				return compressed.err
+			}
+		}
+		if r.err != nil {
+			return r.err
+		}
+		if uint64(face.Shading) >= uint64(len(mesh.Shadings)) {
+			return fmt.Errorf("invalid U3D face shading index")
+		}
+		shading := &mesh.Shadings[face.Shading]
+		for cornerIndex := range face.Corners {
+			corner := &face.Corners[cornerIndex]
+			var err error
+			if corner.Position, err = readIndex(counts[1]); err != nil {
+				return err
+			}
+			if !mesh.ExcludeNormals {
+				if corner.Normal, err = readIndex(counts[2]); err != nil {
+					return err
+				}
+			}
+			if shading.Attributes&1 != 0 {
+				if corner.Diffuse, err = readIndex(counts[3]); err != nil {
+					return err
+				}
+			}
+			if shading.Attributes&2 != 0 {
+				if corner.Specular, err = readIndex(counts[4]); err != nil {
+					return err
+				}
+			}
+			for layer := range shading.TextureDimensions {
+				if corner.Texture[layer], err = readIndex(counts[5]); err != nil {
+					return err
+				}
+			}
+		}
+	}
+	if compressed != nil {
+		if compressed.pos > uint64(len(compressed.data))*8 {
+			return io.ErrUnexpectedEOF
+		}
+		if compressed.u32() != 0 {
+			return fmt.Errorf("invalid U3D compression flush")
+		}
+		if compressed.err != nil {
+			return compressed.err
+		}
+		if (compressed.pos-16+7)/8 != uint64(len(compressed.data)) {
+			return fmt.Errorf("unexpected U3D compressed block data: decoded %d bits, stored %d bytes", compressed.pos-16, len(compressed.data))
+		}
+		r.pos = len(r.data)
+	}
+	decl.decoded = true
+	return r.done()
+}

ofdgo_u3d_render.go

@@ -0,0 +1,443 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"context"
+	"fmt"
+	"image"
+	"math"
+)
+
+// U3DCamera 定义沿正Z方向观察的相机，ScaleX和ScaleY为投影到像素的倍率
+// ToWorld按列存储，全零表示单位矩阵；Far为0且ClipFar为假时不设置远裁剪面
+// ShiftX和ShiftY为投影原点相对视口中心的像素偏移，向右及向下为正
+type U3DCamera struct {
+	ToWorld                   [16]float64
+	Perspective               bool
+	ScaleX, ScaleY, Near, Far float64
+	ShiftX, ShiftY            float64
+	ClipFar                   bool
+}
+
+// U3DRenderOptions 控制静态绘制，指定Camera时使用整个输出视口
+// Camera为空时使用View指定的节点或首个视图节点，Instance指定其父路径实例
+// Lighting为空时沿用模型灯光，非空时替换全部模型灯光
+// Nodes按名称覆盖节点，重复名称使用最后一项，每次绘制均从原场景开始
+// Background为空时使用白色；缓存与实例上限为0时分别使用256MiB和65536，不含输入及运行时开销
+type U3DRenderOptions struct {
+	Width, Height  int
+	View           string
+	Instance       int
+	Camera         *U3DCamera
+	Background     *[3]float64
+	Lighting       *U3DLighting
+	Nodes          []U3DNodeState
+	Sections       []U3DCrossSection
+	MaxMemoryBytes int64
+	MaxInstances   int
+}
+
+// u3dPixel 保存不透明底色、最近深度及透明片元链
+type u3dPixel struct {
+	color [3]float64
+	depth float64
+	order uint64
+	head  int32
+}
+
+// u3dFragment 保存等待按像素深度混合的透明或非覆盖片元
+type u3dFragment struct {
+	color [4]float64
+	depth float64
+	order uint64
+	blend uint32
+	next  int32
+}
+
+// u3dRender 保存一次绘制的有限预算，不修改调用方场景
+type u3dRender struct {
+	ctx                                    context.Context
+	model                                  *U3DModel
+	remaining                              uint64
+	frame                                  []u3dPixel
+	output                                 *image.RGBA
+	viewport                               [4]float64
+	camera                                 U3DCamera
+	toCamera                               u3dMatrix
+	scene                                  []u3dInstance
+	byNode                                 [][]int
+	members                                []bool
+	meshes, shaders, materials, lightIndex map[string]int
+	lights                                 []u3dRenderLight
+	lighting                               *U3DLighting
+	states                                 map[string]U3DNodeState
+	sections                               []u3dSection
+	sectionScratch                         [2][]u3dVertex
+	chunks                                 [][]u3dFragment
+	fragments                              int
+	scratch                                []int
+	order                                  uint64
+}
+
+// RenderU3D 绘制静态无纹理三角面，返回不透明图像，不执行脚本或动画
+// 采用逐顶点光照及逐像素深度混合，缺失资源回退为空网格、灰色材质或无光源
+// 入参: ctx 取消上下文, model 场景, options 视图、输出与资源限制
+// 返回: *image.RGBA 图像, error 参数、能力、预算或取消错误
+func RenderU3D(ctx context.Context, model *U3DModel, options U3DRenderOptions) (*image.RGBA, error) {
+	r, err := newU3DRender(ctx, model, options)
+	if err != nil {
+		return nil, err
+	}
+	passes, err := r.selectView(options)
+	if err != nil {
+		return nil, err
+	}
+	return r.render(options, passes)
+}
+
+// newU3DRender 建立有预算限制的场景实例与资源索引
+// 入参: ctx 取消上下文, model 场景, options 输出与资源限制
+// 返回: *u3dRender 绘制状态, error 参数、场景、预算或取消错误
+func newU3DRender(ctx context.Context, model *U3DModel, options U3DRenderOptions) (*u3dRender, error) {
+	if ctx == nil || model == nil || options.Width <= 0 || options.Height <= 0 || options.MaxMemoryBytes < 0 || options.MaxInstances < 0 || options.Instance < 0 {
+		return nil, fmt.Errorf("invalid U3D render options")
+	}
+	limit := options.MaxMemoryBytes
+	if limit == 0 {
+		limit = u3dDefaultBytes
+	}
+	r := &u3dRender{ctx: ctx, model: model, remaining: uint64(limit)}
+	if uint64(options.Width) > uint64(^uint(0)>>1)/uint64(options.Height) {
+		return nil, fmt.Errorf("invalid U3D render dimensions")
+	}
+	pixels := uint64(options.Width) * uint64(options.Height)
+	if err := r.reserve(pixels, 60); err != nil {
+		return nil, err
+	}
+	maxInstances := options.MaxInstances
+	if maxInstances == 0 {
+		maxInstances = 65536
+	}
+	if err := r.nodeStates(options.Nodes); err != nil {
+		return nil, err
+	}
+	if err := r.instances(maxInstances); err != nil {
+		return nil, err
+	}
+	if err := r.reserve(uint64(len(r.scene)), 1); err != nil {
+		return nil, err
+	}
+	r.members = make([]bool, len(r.scene))
+	if err := r.resources(); err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+// render 在已选择的相机和轮次下生成图像
+// 入参: options 输出与灯光背景, passes 绘制轮次
+// 返回: *image.RGBA 图像, error 参数、绘制、预算或取消错误
+func (r *u3dRender) render(options U3DRenderOptions, passes []U3DViewPass) (*image.RGBA, error) {
+	if r.sections == nil {
+		if err := r.prepareSections(options.Sections); err != nil {
+			return nil, err
+		}
+	}
+	if err := r.overrideLighting(options.Lighting); err != nil {
+		return nil, err
+	}
+	background := [3]float64{1, 1, 1}
+	if options.Background != nil {
+		background = *options.Background
+	}
+	for i, v := range background {
+		if !finite(v) {
+			return nil, fmt.Errorf("invalid U3D background")
+		}
+		background[i] = min(1, max(0, v))
+	}
+	r.frame = make([]u3dPixel, options.Width*options.Height)
+	r.output = image.NewRGBA(image.Rect(0, 0, options.Width, options.Height))
+	for i := range r.frame {
+		if i%4096 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return nil, err
+			}
+		}
+		r.frame[i].color = background
+	}
+	for passIndex, pass := range passes {
+		if err := r.renderPass(pass, passIndex, passIndex == len(passes)-1); err != nil {
+			return nil, err
+		}
+	}
+	for i, pixel := range r.frame {
+		if i%4096 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return nil, err
+			}
+		}
+		for component, v := range pixel.color {
+			r.output.Pix[i*4+component] = byte(math.Round(min(1, max(0, v)) * 255))
+		}
+		r.output.Pix[i*4+3] = 255
+	}
+	if err := r.ctx.Err(); err != nil {
+		return nil, err
+	}
+	return r.output, nil
+}
+
+// reserve 在分配绘制缓存前扣减预算并检查取消状态
+// 入参: count 元素数量, size 元素预算
+// 返回: error 预算或取消错误
+func (r *u3dRender) reserve(count, size uint64) error {
+	if err := r.ctx.Err(); err != nil {
+		return err
+	}
+	if size == 0 || count > r.remaining/size || count > uint64(^uint(0)>>1)/size {
+		return fmt.Errorf("U3D render memory exceeds limit")
+	}
+	r.remaining -= count * size
+	return nil
+}
+
+// selectView 解析视图与相机覆盖，内部视口使用左上角坐标
+// 入参: options 绘制选项
+// 返回: []U3DViewPass 绘制轮次, error 视图或投影错误
+func (r *u3dRender) selectView(options U3DRenderOptions) ([]U3DViewPass, error) {
+	r.viewport = [4]float64{0, 0, float64(options.Width), float64(options.Height)}
+	selected := -1
+	for i, node := range r.model.Nodes {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return nil, err
+			}
+		}
+		if options.View != "" && node.Name == options.View || options.View == "" && options.Camera == nil && node.Kind == "View" {
+			selected = i
+			break
+		}
+	}
+	if options.View != "" && selected < 0 {
+		return nil, fmt.Errorf("missing U3D view %q", options.View)
+	}
+	passes := []U3DViewPass{{}}
+	if selected >= 0 {
+		node := r.model.Nodes[selected]
+		if node.Kind != "View" || node.View == nil {
+			return nil, fmt.Errorf("invalid U3D view node")
+		}
+		view := node.View
+		if len(view.Backdrops) != 0 || len(view.Overlays) != 0 {
+			return nil, fmt.Errorf("unsupported U3D textured view layers")
+		}
+		found := false
+		for i, resource := range r.model.Views {
+			if i%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return nil, err
+				}
+			}
+			if resource.Name == node.Resource {
+				if found {
+					return nil, fmt.Errorf("duplicate U3D view resource")
+				}
+				passes = resource.Passes
+				found = true
+			}
+		}
+		if options.Camera == nil {
+			if options.Instance >= len(r.byNode[selected]) {
+				return nil, fmt.Errorf("missing U3D camera instance")
+			}
+			r.camera.ToWorld = r.scene[r.byNode[selected][options.Instance]].world
+			if view.Attributes & ^uint32(7) != 0 || view.Attributes&6 >= 4 {
+				return nil, fmt.Errorf("unsupported U3D view projection")
+			}
+			for i, v := range view.Viewport {
+				if !finite(float64(v)) {
+					return nil, fmt.Errorf("invalid U3D viewport")
+				}
+				r.viewport[(i+2)%4] = float64(v)
+			}
+			if view.Attributes&1 != 0 {
+				r.viewport[0] *= float64(options.Width)
+				r.viewport[1] *= float64(options.Height)
+				r.viewport[2] *= float64(options.Width)
+				r.viewport[3] *= float64(options.Height)
+			}
+			if r.viewport[2] <= 0 || r.viewport[3] <= 0 {
+				return nil, fmt.Errorf("invalid U3D viewport size")
+			}
+			r.camera.Near, r.camera.Far = float64(view.Near), float64(view.Far)
+			if r.camera.Far <= r.camera.Near {
+				return nil, fmt.Errorf("invalid U3D view clipping range")
+			}
+			r.camera.Perspective = view.Attributes&6 == 0
+			if r.camera.Perspective {
+				if view.Projection <= 0 || view.Projection >= 180 {
+					return nil, fmt.Errorf("invalid U3D perspective field of view")
+				}
+				r.camera.ScaleY = r.viewport[3] / (2 * math.Tan(float64(view.Projection)*math.Pi/360))
+			} else {
+				if view.Projection <= 0 {
+					return nil, fmt.Errorf("invalid U3D orthographic height")
+				}
+				r.camera.ScaleY = r.viewport[3] / float64(view.Projection)
+			}
+			r.camera.ScaleX = r.camera.ScaleY
+		}
+	}
+	if options.Camera != nil {
+		r.camera = *options.Camera
+	} else if selected < 0 {
+		return nil, fmt.Errorf("missing U3D camera")
+	}
+	if len(passes) > 32 {
+		return nil, fmt.Errorf("unsupported U3D render pass count")
+	}
+	for _, v := range []float64{r.camera.ScaleX, r.camera.ScaleY, r.camera.Near, r.camera.Far, r.camera.ShiftX, r.camera.ShiftY} {
+		if !finite(v) {
+			return nil, fmt.Errorf("invalid U3D camera values")
+		}
+	}
+	if r.camera.ScaleX <= 0 || r.camera.ScaleY <= 0 || r.camera.Perspective && r.camera.Near <= 0 || (r.camera.ClipFar || r.camera.Far != 0) && r.camera.Far < r.camera.Near {
+		return nil, fmt.Errorf("invalid U3D camera projection")
+	}
+	matrix := u3dMatrix(r.camera.ToWorld)
+	if matrix == (u3dMatrix{}) {
+		matrix = u3dIdentity()
+	}
+	var ok bool
+	r.toCamera, ok = matrix.inverse()
+	if !ok {
+		return nil, fmt.Errorf("invalid U3D camera transform")
+	}
+	return passes, nil
+}
+
+// resources 建立只读资源索引，不按名称反复扫描场景
+// 返回: error 重名或预算错误
+func (r *u3dRender) resources() error {
+	count := uint64(len(r.model.Meshes)) + uint64(len(r.model.Shaders)) + uint64(len(r.model.Materials)) + uint64(len(r.model.Lights))
+	if err := r.reserve(count, 96); err != nil {
+		return err
+	}
+	r.meshes = make(map[string]int, len(r.model.Meshes))
+	r.shaders = make(map[string]int, len(r.model.Shaders))
+	r.materials = make(map[string]int, len(r.model.Materials))
+	r.lightIndex = make(map[string]int, len(r.model.Lights))
+	add := func(index map[string]int, name string, i int) error {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if _, ok := index[name]; ok {
+			return fmt.Errorf("duplicate U3D render resource %q", name)
+		}
+		index[name] = i
+		return nil
+	}
+	for i, v := range r.model.Meshes {
+		if err := add(r.meshes, v.Name, i); err != nil {
+			return err
+		}
+	}
+	for i, v := range r.model.Shaders {
+		if err := add(r.shaders, v.Name, i); err != nil {
+			return err
+		}
+	}
+	for i, v := range r.model.Materials {
+		if err := add(r.materials, v.Name, i); err != nil {
+			return err
+		}
+	}
+	for i, v := range r.model.Lights {
+		if err := add(r.lightIndex, v.Name, i); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// renderPass 分别解析遮挡与混合，绘制轮次之间保留颜色并重置深度
+// 入参: pass 轮次参数, passIndex 轮次索引, last 是否为最后一轮
+// 返回: error 场景、预算或取消错误
+func (r *u3dRender) renderPass(pass U3DViewPass, passIndex int, last bool) error {
+	if pass.Attributes > 1 || pass.FogMode > 2 {
+		return fmt.Errorf("invalid U3D render pass")
+	}
+	if pass.Attributes&1 != 0 {
+		for _, v := range append(pass.FogColor[:], pass.FogNear, pass.FogFar) {
+			if !finite(float64(v)) {
+				return fmt.Errorf("invalid U3D fog value")
+			}
+		}
+		if pass.FogMode == 0 && pass.FogFar <= pass.FogNear || pass.FogMode != 0 && pass.FogFar <= 0 {
+			return fmt.Errorf("invalid U3D fog range")
+		}
+	}
+	for i, instance := range r.scene {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		r.members[i] = pass.Root == "" || r.model.Nodes[instance.node].Name == pass.Root || instance.parent >= 0 && r.members[instance.parent]
+	}
+	for i := range r.frame {
+		if i%4096 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		r.frame[i].depth = math.Inf(1)
+		r.frame[i].order = 0
+		r.frame[i].head = -1
+	}
+	r.fragments = 0
+	if err := r.collectLights(); err != nil {
+		return err
+	}
+	for i, instance := range r.scene {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		node := &r.model.Nodes[instance.node]
+		if !r.members[i] || node.Kind != "Model" || instance.modelVisibility(node) == 0 || instance.opacity == 0 {
+			continue
+		}
+		if node.Visibility > 3 {
+			return fmt.Errorf("invalid U3D model visibility")
+		}
+		mesh, ok := r.meshes[node.Resource]
+		if !ok {
+			continue
+		}
+		if err := r.drawMesh(instance, node, &r.model.Meshes[mesh], pass, passIndex); err != nil {
+			return err
+		}
+	}
+	if last {
+		if err := r.drawSectionPlanes(); err != nil {
+			return err
+		}
+	}
+	return r.resolveFragments()
+}

ofdgo_u3d_scene.go

@@ -0,0 +1,303 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+)
+
+// u3dVector 保存计算过程中的三维双精度坐标
+type u3dVector [3]float64
+
+// u3dMatrix 保存按列排列的仿射矩阵
+type u3dMatrix [16]float64
+
+// u3dInstance 保存一个父路径产生的世界实例，parent为负值时连接默认根
+type u3dInstance struct {
+	node, parent int
+	world        u3dMatrix
+	opacity      float64
+	visibility   int8
+}
+
+// u3dIdentity 创建单位矩阵
+// 返回: u3dMatrix 单位矩阵
+func u3dIdentity() u3dMatrix { return u3dMatrix{1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1} }
+
+// multiply 连接子节点到父节点的变换
+// 入参: other 子变换
+// 返回: u3dMatrix 组合变换
+func (m u3dMatrix) multiply(other u3dMatrix) u3dMatrix {
+	var result u3dMatrix
+	for column := range 4 {
+		for row := range 4 {
+			for k := range 4 {
+				result[column*4+row] += m[k*4+row] * other[column*4+k]
+			}
+		}
+	}
+	return result
+}
+
+// valid 判断矩阵是否为有限仿射变换
+// 返回: bool 是否可用于静态绘制
+func (m u3dMatrix) valid() bool {
+	for _, v := range m {
+		if !finite(v) {
+			return false
+		}
+	}
+	return m[3] == 0 && m[7] == 0 && m[11] == 0 && m[15] == 1
+}
+
+// point 将点从局部坐标映射到目标坐标
+// 入参: p 局部点
+// 返回: u3dVector 目标点
+func (m u3dMatrix) point(p u3dVector) u3dVector {
+	return u3dVector{m[0]*p[0] + m[4]*p[1] + m[8]*p[2] + m[12], m[1]*p[0] + m[5]*p[1] + m[9]*p[2] + m[13], m[2]*p[0] + m[6]*p[1] + m[10]*p[2] + m[14]}
+}
+
+// inverse 通过带主元消元计算仿射逆矩阵
+// 返回: u3dMatrix 逆矩阵, bool 是否存在有限逆矩阵
+func (m u3dMatrix) inverse() (u3dMatrix, bool) {
+	if !m.valid() {
+		return u3dMatrix{}, false
+	}
+	var rows [3][6]float64
+	for i := range 3 {
+		for j := range 3 {
+			rows[i][j] = m[j*4+i]
+		}
+		rows[i][i+3] = 1
+	}
+	for column := range 3 {
+		pivot := column
+		for row := column + 1; row < 3; row++ {
+			if math.Abs(rows[row][column]) > math.Abs(rows[pivot][column]) {
+				pivot = row
+			}
+		}
+		if rows[pivot][column] == 0 {
+			return u3dMatrix{}, false
+		}
+		rows[pivot], rows[column] = rows[column], rows[pivot]
+		divisor := rows[column][column]
+		for j := range 6 {
+			rows[column][j] /= divisor
+		}
+		for row := range 3 {
+			if row != column {
+				factor := rows[row][column]
+				for j := range 6 {
+					rows[row][j] -= factor * rows[column][j]
+				}
+			}
+		}
+	}
+	result := u3dIdentity()
+	for row := range 3 {
+		for col := range 3 {
+			result[col*4+row] = rows[row][col+3]
+		}
+		result[12+row] = -(result[row]*m[12] + result[4+row]*m[13] + result[8+row]*m[14])
+	}
+	return result, result.valid()
+}
+
+// normal 以逆矩阵的转置变换并归一化法线
+// 入参: n 局部法线，接收者为局部变换的逆矩阵
+// 返回: u3dVector 目标法线
+func (m u3dMatrix) normal(n u3dVector) u3dVector {
+	return (u3dVector{m[0]*n[0] + m[1]*n[1] + m[2]*n[2], m[4]*n[0] + m[5]*n[1] + m[6]*n[2], m[8]*n[0] + m[9]*n[1] + m[10]*n[2]}).unit()
+}
+
+// unit 归一化向量，零向量保持为零
+// 返回: u3dVector 单位向量
+func (v u3dVector) unit() u3dVector {
+	scale := max(math.Abs(v[0]), math.Abs(v[1]), math.Abs(v[2]))
+	if scale == 0 || !finite(scale) {
+		return u3dVector{}
+	}
+	for i := range v {
+		v[i] /= scale
+	}
+	length := math.Sqrt(v.dot(v))
+	return u3dVector{v[0] / length, v[1] / length, v[2] / length}
+}
+
+// sub 求向量差
+// 入参: other 被减向量
+// 返回: u3dVector 差向量
+func (v u3dVector) sub(other u3dVector) u3dVector {
+	return u3dVector{v[0] - other[0], v[1] - other[1], v[2] - other[2]}
+}
+
+// dot 求向量内积
+// 入参: other 另一向量
+// 返回: float64 内积
+func (v u3dVector) dot(other u3dVector) float64 { return v[0]*other[0] + v[1]*other[1] + v[2]*other[2] }
+
+// cross 求向量叉积
+// 入参: other 另一向量
+// 返回: u3dVector 叉积
+func (v u3dVector) cross(other u3dVector) u3dVector {
+	return u3dVector{v[1]*other[2] - v[2]*other[1], v[2]*other[0] - v[0]*other[2], v[0]*other[1] - v[1]*other[0]}
+}
+
+// u3dTriangleNormal 选取夹角更稳定的顶点计算法线，避免长瘦三角面的相消
+// 入参: points 按绕序排列的顶点
+// 返回: u3dVector 单位法线，退化三角面返回零向量
+func u3dTriangleNormal(points [3]u3dVector) u3dVector {
+	var normal u3dVector
+	score := 0.0
+	for i := range 3 {
+		a := points[(i+1)%3].sub(points[i]).unit()
+		b := points[(i+2)%3].sub(points[i]).unit()
+		candidate := a.cross(b)
+		if length := max(math.Abs(candidate[0]), math.Abs(candidate[1]), math.Abs(candidate[2])); length > score {
+			normal, score = candidate, length
+		}
+	}
+	return normal.unit()
+}
+
+// instances 按拓扑顺序构建全部父路径实例，限制共享层级的指数展开
+// 入参: limit 最大实例数
+// 返回: error 结构、预算、实例上限或取消错误
+func (r *u3dRender) instances(limit int) error {
+	nodes := r.model.Nodes
+	if err := r.reserve(uint64(len(nodes)), 160); err != nil {
+		return err
+	}
+	index := make(map[string]int, len(nodes))
+	for i, node := range nodes {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if _, exists := index[node.Name]; exists || node.Name == "" {
+			return fmt.Errorf("invalid U3D render node name")
+		}
+		switch node.Kind {
+		case "Group", "Model", "Light", "View":
+		default:
+			return fmt.Errorf("unsupported U3D render node kind")
+		}
+		index[node.Name] = i
+	}
+	counts := make([]int, len(nodes))
+	children := make([][]int, len(nodes))
+	r.byNode = make([][]int, len(nodes))
+	for i, node := range nodes {
+		if err := r.reserve(uint64(len(node.Parents)), 16); err != nil {
+			return err
+		}
+		for k, parent := range node.Parents {
+			if k%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			if j, ok := index[parent.Name]; ok {
+				counts[i]++
+				children[j] = append(children[j], i)
+			}
+		}
+	}
+	queue := make([]int, 0, len(nodes))
+	for i, n := range counts {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if n == 0 {
+			queue = append(queue, i)
+		}
+	}
+	for cursor := 0; cursor < len(queue); cursor++ {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		i := queue[cursor]
+		state := r.states[nodes[i].Name]
+		for parentIndex, parent := range nodes[i].Parents {
+			if parentIndex%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			var local u3dMatrix
+			for k, v := range parent.Transform {
+				local[k] = float64(v)
+			}
+			if state.Matrix != nil {
+				local = *state.Matrix
+			}
+			if !local.valid() {
+				return fmt.Errorf("unsupported U3D non-affine node transform")
+			}
+			parents := []int{-1}
+			if j, ok := index[parent.Name]; ok {
+				parents = r.byNode[j]
+			}
+			for _, p := range parents {
+				if len(r.scene) >= limit {
+					return fmt.Errorf("U3D instance count exceeds limit")
+				}
+				if err := r.reserve(1, 384); err != nil {
+					return err
+				}
+				world := local
+				opacity, visibility := -1.0, int8(-1)
+				if p >= 0 {
+					world = r.scene[p].world.multiply(local)
+					opacity, visibility = r.scene[p].opacity, r.scene[p].visibility
+				}
+				if state.Opacity != nil {
+					opacity = *state.Opacity
+				}
+				if state.Visible != nil {
+					visibility = 0
+					if *state.Visible {
+						visibility = 1
+					}
+				}
+				if !world.valid() {
+					return fmt.Errorf("invalid U3D world transform")
+				}
+				r.byNode[i] = append(r.byNode[i], len(r.scene))
+				r.scene = append(r.scene, u3dInstance{node: i, parent: p, world: world, opacity: opacity, visibility: visibility})
+			}
+		}
+		for childIndex, child := range children[i] {
+			if childIndex%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			counts[child]--
+			if counts[child] == 0 {
+				queue = append(queue, child)
+			}
+		}
+	}
+	if len(queue) != len(nodes) {
+		return fmt.Errorf("cyclic U3D node parents")
+	}
+	return nil
+}

ofdgo_u3d_section.go

@@ -0,0 +1,280 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+)
+
+// U3DCrossSection 定义世界坐标中的剖切面，AxisU与AxisV须为非零正交方向
+// 两轴叉积指向被裁去的一侧；平面方形边长取静态场景包围盒对角线
+// Opacity为0时不显示平面，Intersection为空时不显示交线，颜色分量范围为0到1
+type U3DCrossSection struct {
+	Center, AxisU, AxisV [3]float64
+	Opacity              float64
+	Color                [3]float64
+	Intersection         *[3]float64
+}
+
+// u3dSection 保存相机空间裁剪方程、平面四角与交线颜色
+type u3dSection struct {
+	plane        [4]float64
+	corners      [4]u3dVertex
+	intersection *[3]float64
+	opacity      float64
+}
+
+// prepareSections 准备剖切缓存，不复制网格或修改调用方参数
+// 入参: sections 世界坐标剖切面
+// 返回: error 参数、场景、预算或取消错误
+func (r *u3dRender) prepareSections(sections []U3DCrossSection) error {
+	if len(sections) == 0 {
+		return nil
+	}
+	if err := r.reserve(uint64(len(sections)), 352); err != nil {
+		return err
+	}
+	if err := r.reserve(uint64(len(sections))+3, 112); err != nil {
+		return err
+	}
+	r.sections = make([]u3dSection, len(sections))
+	for i := range r.sectionScratch {
+		r.sectionScratch[i] = make([]u3dVertex, len(sections)+3)
+	}
+	visible := false
+	for i, section := range sections {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if !finite(section.Opacity) || section.Opacity < 0 || section.Opacity > 1 {
+			return fmt.Errorf("invalid U3D section opacity")
+		}
+		visible = visible || section.Opacity > 0
+	}
+	diagonal := 0.0
+	if visible {
+		var err error
+		diagonal, err = r.sceneDiagonal()
+		if err != nil {
+			return err
+		}
+	}
+	world := u3dMatrix(r.camera.ToWorld)
+	if world == (u3dMatrix{}) {
+		world = u3dIdentity()
+	}
+	for i, section := range sections {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		for _, vector := range [][3]float64{section.Center, section.AxisU, section.AxisV} {
+			for _, value := range vector {
+				if !finite(value) {
+					return fmt.Errorf("invalid U3D section coordinates")
+				}
+			}
+		}
+		for _, color := range []*[3]float64{&section.Color, section.Intersection} {
+			if color != nil {
+				for _, v := range color {
+					if !finite(v) || v < 0 || v > 1 {
+						return fmt.Errorf("invalid U3D section color")
+					}
+				}
+			}
+		}
+		u, v := u3dVector(section.AxisU).unit(), u3dVector(section.AxisV).unit()
+		if u == (u3dVector{}) || v == (u3dVector{}) || math.Abs(u.dot(v)) > 1e-12 {
+			return fmt.Errorf("invalid U3D section axes")
+		}
+		normal := u.cross(v).unit()
+		prepared := &r.sections[i]
+		for j := range 3 {
+			prepared.plane[j] = -(normal[0]*world[j*4] + normal[1]*world[j*4+1] + normal[2]*world[j*4+2])
+		}
+		prepared.plane[3] = normal.dot(u3dVector(section.Center).sub(u3dVector{world[12], world[13], world[14]}))
+		for _, coefficient := range prepared.plane {
+			if !finite(coefficient) {
+				return fmt.Errorf("invalid U3D section plane")
+			}
+		}
+		prepared.intersection, prepared.opacity = section.Intersection, section.Opacity
+		for j, signs := range [4][2]float64{{-1, -1}, {1, -1}, {1, 1}, {-1, 1}} {
+			point := u3dVector(section.Center)
+			for k := range point {
+				point[k] += diagonal / 2 * (signs[0]*u[k] + signs[1]*v[k])
+			}
+			prepared.corners[j] = u3dVertex{point: r.toCamera.point(point), color: [4]float64{section.Color[0], section.Color[1], section.Color[2], section.Opacity}}
+			for _, coordinate := range prepared.corners[j].point {
+				if !finite(coordinate) {
+					return fmt.Errorf("invalid U3D section corner")
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// sceneDiagonal 计算静态场景世界包围盒的对角线，包含隐藏节点的几何
+// 返回: float64 对角线长度, error 几何、数值或取消错误
+func (r *u3dRender) sceneDiagonal() (float64, error) {
+	minimum := u3dVector{math.Inf(1), math.Inf(1), math.Inf(1)}
+	maximum := u3dVector{math.Inf(-1), math.Inf(-1), math.Inf(-1)}
+	for _, instance := range r.scene {
+		if err := r.ctx.Err(); err != nil {
+			return 0, err
+		}
+		node := r.model.Nodes[instance.node]
+		index, exists := r.meshes[node.Resource]
+		if node.Kind != "Model" || !exists {
+			continue
+		}
+		mesh := &r.model.Meshes[index]
+		for i, face := range mesh.Faces {
+			if i%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return 0, err
+				}
+			}
+			for _, corner := range face.Corners {
+				if uint64(corner.Position) >= uint64(len(mesh.Positions)) {
+					return 0, fmt.Errorf("invalid U3D position index")
+				}
+				p := mesh.Positions[corner.Position]
+				world := instance.world.point(u3dVector{float64(p[0]), float64(p[1]), float64(p[2])})
+				for j, v := range world {
+					if !finite(v) {
+						return 0, fmt.Errorf("invalid U3D scene bounds")
+					}
+					minimum[j], maximum[j] = min(minimum[j], v), max(maximum[j], v)
+				}
+			}
+		}
+	}
+	if math.IsInf(minimum[0], 1) {
+		return 0, nil
+	}
+	delta := maximum.sub(minimum)
+	diagonal := math.Hypot(math.Hypot(delta[0], delta[1]), delta[2])
+	if !finite(diagonal) {
+		return 0, fmt.Errorf("invalid U3D scene diagonal")
+	}
+	return diagonal, nil
+}
+
+// sectionTriangle 用复用的凸多边形缓存应用全部剖切面，再进行视锥裁剪
+// 入参: triangle 三角面, shader 着色器, pass 绘制轮次
+// 返回: error 数值、资源或取消错误
+func (r *u3dRender) sectionTriangle(triangle [3]u3dVertex, shader U3DShader, pass U3DViewPass) error {
+	if len(r.sections) == 0 {
+		return r.clipTriangle(triangle, shader, pass)
+	}
+	copy(r.sectionScratch[0], triangle[:])
+	size, current := 3, 0
+	for _, section := range r.sections {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		next, count := 1-current, 0
+		previous := r.sectionScratch[current][size-1]
+		previousDistance := u3dPlaneDistance(section.plane, previous.point)
+		for i, vertex := range r.sectionScratch[current][:size] {
+			if i%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			distance := u3dPlaneDistance(section.plane, vertex.point)
+			if !finite(distance) || !finite(previousDistance) {
+				return fmt.Errorf("invalid U3D section distance")
+			}
+			if (distance >= 0) != (previousDistance >= 0) {
+				var err error
+				count, err = u3dAppendSectionVertex(r.sectionScratch[next], count, u3dInterpolate(previous, vertex, u3dClipFraction(previousDistance, distance)))
+				if err != nil {
+					return err
+				}
+			}
+			if distance >= 0 {
+				var err error
+				count, err = u3dAppendSectionVertex(r.sectionScratch[next], count, vertex)
+				if err != nil {
+					return err
+				}
+			}
+			previous, previousDistance = vertex, distance
+		}
+		if count > 1 && r.sectionScratch[next][0].point == r.sectionScratch[next][count-1].point {
+			count--
+		}
+		size, current = count, next
+		if size < 3 {
+			break
+		}
+	}
+	if size < 2 {
+		return nil
+	}
+	for i := 1; i+1 < size; i++ {
+		if err := r.clipTriangle([3]u3dVertex{r.sectionScratch[current][0], r.sectionScratch[current][i], r.sectionScratch[current][i+1]}, shader, pass); err != nil {
+			return err
+		}
+	}
+	for i, section := range r.sections {
+		if section.intersection != nil {
+			if err := r.sectionIntersection(triangle, i); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// u3dAppendSectionVertex 合并连续重复交点，维持凸多边形缓存上限
+// 入参: buffer 固定缓存, count 已有顶点数, vertex 新顶点
+// 返回: int 顶点数, error 缓存越界错误
+func u3dAppendSectionVertex(buffer []u3dVertex, count int, vertex u3dVertex) (int, error) {
+	if count > 0 && buffer[count-1].point == vertex.point {
+		return count, nil
+	}
+	if count >= len(buffer) {
+		return count, fmt.Errorf("invalid U3D section polygon")
+	}
+	buffer[count] = vertex
+	return count + 1, nil
+}
+
+// drawSectionPlanes 在最后一轮绘制平面方形，不把平面本身当作待剖切几何
+// 返回: error 数值、资源或取消错误
+func (r *u3dRender) drawSectionPlanes() error {
+	for _, section := range r.sections {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		if section.opacity == 0 {
+			continue
+		}
+		for i := 1; i < 3; i++ {
+			r.order++
+			if err := r.clipTriangle([3]u3dVertex{section.corners[0], section.corners[i], section.corners[i+1]}, U3DShader{Blend: 0x606}, U3DViewPass{}); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}

ofdgo_u3d_state.go

@@ -0,0 +1,73 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import "fmt"
+
+// U3DNodeState 按名称覆盖节点，未指定透明度或可见性时沿父路径继承
+// Opacity范围为0到1，采用标准透明混合；Matrix为相对父节点的列式仿射矩阵
+// 未匹配的名称不影响场景，矩阵为空时保留每条父路径的原始变换
+type U3DNodeState struct {
+	Name    string
+	Opacity *float64
+	Visible *bool
+	Matrix  *[16]float64
+}
+
+// nodeStates 建立有预算限制的覆盖索引，重复名称整体替换而不合并字段
+// 入参: states 节点覆盖
+// 返回: error 数值、预算或取消错误
+func (r *u3dRender) nodeStates(states []U3DNodeState) error {
+	if len(states) == 0 {
+		return nil
+	}
+	if err := r.reserve(uint64(len(states)), 128); err != nil {
+		return err
+	}
+	r.states = make(map[string]U3DNodeState, len(states))
+	for i, state := range states {
+		if i%256 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		r.states[state.Name] = state
+	}
+	for _, state := range r.states {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		if state.Opacity != nil && (!finite(*state.Opacity) || *state.Opacity < 0 || *state.Opacity > 1) {
+			return fmt.Errorf("invalid U3D node opacity")
+		}
+		if state.Matrix != nil && !u3dMatrix(*state.Matrix).valid() {
+			return fmt.Errorf("invalid U3D node matrix")
+		}
+	}
+	return nil
+}
+
+// modelVisibility 在节点覆盖生效时恢复隐藏模型，保留原有正反面选择
+// 入参: node 模型节点
+// 返回: uint32 可见面标志
+func (instance u3dInstance) modelVisibility(node *U3DNode) uint32 {
+	if instance.visibility == 0 {
+		return 0
+	}
+	if instance.visibility == 1 && node.Visibility == 0 {
+		return 3
+	}
+	return node.Visibility
+}

ofdgo_u3d_triangle.go

@@ -0,0 +1,464 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+	"slices"
+)
+
+// u3dVertex 保存裁剪前后的相机坐标及未预乘颜色
+type u3dVertex struct {
+	point u3dVector
+	color [4]float64
+}
+
+// drawMesh 按实例复用顶点变换，着色列表按指定顺序绘制
+// 入参: instance 场景实例, node 模型节点, mesh 网格, pass 绘制轮次, passIndex 轮次索引
+// 返回: error 几何、资源或取消错误
+func (r *u3dRender) drawMesh(instance u3dInstance, node *U3DNode, mesh *U3DMesh, pass U3DViewPass, passIndex int) error {
+	count := uint64(len(mesh.Positions)) + uint64(len(mesh.Normals))
+	if err := r.reserve(count, 24); err != nil {
+		return err
+	}
+	defer func() { r.remaining += count * 24 }()
+	positions := make([]u3dVector, len(mesh.Positions))
+	normals := make([]u3dVector, len(mesh.Normals))
+	inverse, invertible := instance.world.inverse()
+	for i, p := range mesh.Positions {
+		if i%1024 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		positions[i] = instance.world.point(u3dVector{float64(p[0]), float64(p[1]), float64(p[2])})
+		for _, v := range positions[i] {
+			if !finite(v) {
+				return fmt.Errorf("invalid U3D transformed position")
+			}
+		}
+	}
+	for i, n := range mesh.Normals {
+		if i%1024 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		for _, v := range n {
+			if !finite(float64(v)) {
+				return fmt.Errorf("invalid U3D normal")
+			}
+		}
+		if invertible {
+			normals[i] = inverse.normal(u3dVector{float64(n[0]), float64(n[1]), float64(n[2])})
+		}
+	}
+	for index, face := range mesh.Faces {
+		if index%128 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		if uint64(face.Shading) >= uint64(len(mesh.Shadings)) {
+			return fmt.Errorf("invalid U3D render shading index")
+		}
+		shading := mesh.Shadings[face.Shading]
+		if shading.Attributes > 3 || len(shading.TextureDimensions) > 8 {
+			return fmt.Errorf("invalid U3D render shading")
+		}
+		var world [3]u3dVector
+		var vertices [3]u3dVertex
+		for i, corner := range face.Corners {
+			if uint64(corner.Position) >= uint64(len(positions)) || !mesh.ExcludeNormals && uint64(corner.Normal) >= uint64(len(normals)) || shading.Attributes&1 != 0 && uint64(corner.Diffuse) >= uint64(len(mesh.Diffuse)) || shading.Attributes&2 != 0 && uint64(corner.Specular) >= uint64(len(mesh.Specular)) {
+				return fmt.Errorf("invalid U3D render corner index")
+			}
+			world[i] = positions[corner.Position]
+			vertices[i].point = r.toCamera.point(world[i])
+			for _, v := range vertices[i].point {
+				if !finite(v) {
+					return fmt.Errorf("invalid U3D camera position")
+				}
+			}
+		}
+		var faceNormal u3dVector
+		if mesh.ExcludeNormals || !invertible {
+			faceNormal = u3dTriangleNormal(world)
+		}
+		p0, p1, p2 := vertices[0].point, vertices[1].point, vertices[2].point
+		facing := (p1[0]-p0[0])*(p2[1]-p0[1]) - (p1[1]-p0[1])*(p2[0]-p0[0])
+		if r.camera.Perspective {
+			facing = p0.unit().dot(p1.unit().cross(p2.unit()))
+		}
+		if !finite(facing) {
+			return fmt.Errorf("invalid U3D face orientation")
+		}
+		front := facing < 0
+		visibility := instance.modelVisibility(node)
+		if facing == 0 || front && visibility&1 == 0 || !front && visibility&2 == 0 {
+			continue
+		}
+		shaderNames := []string{""}
+		if uint64(face.Shading) < uint64(len(node.Shaders)) {
+			shaderNames = node.Shaders[face.Shading]
+		}
+		for shaderIndex, name := range shaderNames {
+			if shaderIndex%128 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			style, err := r.style(name)
+			if err != nil {
+				return err
+			}
+			if style.shader.RenderPass&(1<<passIndex) == 0 {
+				continue
+			}
+			if instance.opacity >= 0 {
+				style.shader.Blend = 0x606
+			}
+			for i, corner := range face.Corners {
+				normal := faceNormal
+				if !mesh.ExcludeNormals && invertible {
+					normal = normals[corner.Normal]
+				}
+				if !front {
+					for j := range normal {
+						normal[j] = -normal[j]
+					}
+				}
+				var diffuse, specular *[4]float32
+				if shading.Attributes&1 != 0 {
+					diffuse = &mesh.Diffuse[corner.Diffuse]
+				}
+				if shading.Attributes&2 != 0 {
+					specular = &mesh.Specular[corner.Specular]
+				}
+				vertices[i].color, err = r.shade(world[i], normal, style, diffuse, specular)
+				if err != nil {
+					return err
+				}
+				if instance.opacity >= 0 {
+					vertices[i].color[3] = instance.opacity
+				}
+			}
+			r.order++
+			if err := r.sectionTriangle(vertices, style.shader, pass); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// clipTriangle 在透视除法前裁剪六个视锥面，避免近面穿越或屏外巨大坐标
+// 入参: triangle 三角面, shader 着色器, pass 绘制轮次
+// 返回: error 数值、资源或取消错误
+func (r *u3dRender) clipTriangle(triangle [3]u3dVertex, shader U3DShader, pass U3DViewPass) error {
+	var storage [2][12]u3dVertex
+	copy(storage[0][:], triangle[:])
+	size, current := 3, 0
+	planes := r.frustumPlanes()
+	for planeIndex, plane := range planes {
+		if planeIndex == 1 && r.camera.Far == 0 && !r.camera.ClipFar {
+			continue
+		}
+		output, next := 0, 1-current
+		previous := storage[current][size-1]
+		distance := func(v u3dVertex) float64 {
+			return plane[0]*v.point[0] + plane[1]*v.point[1] + plane[2]*v.point[2] + plane[3]
+		}
+		previousDistance := distance(previous)
+		for _, vertex := range storage[current][:size] {
+			d := distance(vertex)
+			if !finite(d) || !finite(previousDistance) {
+				return fmt.Errorf("invalid U3D clip distance")
+			}
+			if (d >= 0) != (previousDistance >= 0) {
+				t := u3dClipFraction(previousDistance, d)
+				var intersection u3dVertex
+				for i := range intersection.point {
+					intersection.point[i] = previous.point[i]*(1-t) + vertex.point[i]*t
+				}
+				for i := range intersection.color {
+					intersection.color[i] = previous.color[i]*(1-t) + vertex.color[i]*t
+				}
+				if output == len(storage[next]) {
+					return fmt.Errorf("invalid U3D clipped polygon")
+				}
+				storage[next][output] = intersection
+				output++
+			}
+			if d >= 0 {
+				if output == len(storage[next]) {
+					return fmt.Errorf("invalid U3D clipped polygon")
+				}
+				storage[next][output] = vertex
+				output++
+			}
+			previous, previousDistance = vertex, d
+		}
+		if output < 3 {
+			return nil
+		}
+		current, size = next, output
+	}
+	for i := 1; i+1 < size; i++ {
+		if err := r.rasterTriangle([3]u3dVertex{storage[current][0], storage[current][i], storage[current][i+1]}, shader, pass); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// rasterTriangle 使用像素中心和左上边规则光栅化，透视插值保持颜色与深度一致
+// 入参: triangle 已裁剪三角面, shader 着色器, pass 绘制轮次
+// 返回: error 数值、预算或取消错误
+func (r *u3dRender) rasterTriangle(triangle [3]u3dVertex, shader U3DShader, pass U3DViewPass) error {
+	var x, y, reciprocal [3]float64
+	for i, v := range triangle {
+		reciprocal[i] = 1
+		if r.camera.Perspective {
+			reciprocal[i] = 1 / v.point[2]
+		}
+		x[i] = r.viewport[0] + r.viewport[2]/2 + r.camera.ShiftX + v.point[0]*r.camera.ScaleX*reciprocal[i]
+		y[i] = r.viewport[1] + r.viewport[3]/2 + r.camera.ShiftY - v.point[1]*r.camera.ScaleY*reciprocal[i]
+		if !finite(x[i]) || !finite(y[i]) || !finite(reciprocal[i]) {
+			return fmt.Errorf("invalid U3D projected point")
+		}
+	}
+	area := (x[1]-x[0])*(y[2]-y[0]) - (y[1]-y[0])*(x[2]-x[0])
+	if !finite(area) {
+		return fmt.Errorf("invalid U3D projected area")
+	}
+	if area == 0 {
+		return nil
+	}
+	if area < 0 {
+		triangle[1], triangle[2] = triangle[2], triangle[1]
+		x[1], x[2] = x[2], x[1]
+		y[1], y[2] = y[2], y[1]
+		reciprocal[1], reciprocal[2] = reciprocal[2], reciprocal[1]
+		area = -area
+	}
+	width, height := r.output.Rect.Dx(), r.output.Rect.Dy()
+	left := max(0, math.Ceil(min(x[0], x[1], x[2])-.5))
+	right := min(float64(width-1), math.Floor(max(x[0], x[1], x[2])-.5))
+	top := max(0, math.Ceil(min(y[0], y[1], y[2])-.5))
+	bottom := min(float64(height-1), math.Floor(max(y[0], y[1], y[2])-.5))
+	if left > right || top > bottom {
+		return nil
+	}
+	var inclusive [3]bool
+	for i := range 3 {
+		j := (i + 1) % 3
+		inclusive[i] = y[j] < y[i] || y[j] == y[i] && x[j] > x[i]
+	}
+	for row := int(top); row <= int(bottom); row++ {
+		if err := r.ctx.Err(); err != nil {
+			return err
+		}
+		for column := int(left); column <= int(right); column++ {
+			if column%1024 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			px, py := float64(column)+.5, float64(row)+.5
+			var edge [3]float64
+			inside := true
+			for i := range 3 {
+				j := (i + 1) % 3
+				edge[i] = (x[j]-x[i])*(py-y[i]) - (y[j]-y[i])*(px-x[i])
+				if edge[i] < 0 || edge[i] == 0 && !inclusive[i] {
+					inside = false
+					break
+				}
+			}
+			if !inside {
+				continue
+			}
+			w1, w2 := edge[2]/area, edge[0]/area
+			depth := triangle[0].point[2] + w1*(triangle[1].point[2]-triangle[0].point[2]) + w2*(triangle[2].point[2]-triangle[0].point[2])
+			if r.camera.Perspective {
+				q := edge[1]/area*reciprocal[0] + w1*reciprocal[1] + w2*reciprocal[2]
+				if !finite(q) || q <= 0 {
+					return fmt.Errorf("invalid U3D perspective depth")
+				}
+				w1 = w1 * reciprocal[1] / q
+				w2 = w2 * reciprocal[2] / q
+				depth = 1 / q
+			}
+			pixel := row*width + column
+			if depth > r.frame[pixel].depth {
+				continue
+			}
+			var color [4]float64
+			for c := range color {
+				color[c] = triangle[0].color[c] + w1*(triangle[1].color[c]-triangle[0].color[c]) + w2*(triangle[2].color[c]-triangle[0].color[c])
+				if !finite(color[c]) {
+					return fmt.Errorf("invalid U3D interpolated color")
+				}
+			}
+			color[3] = min(1, max(0, color[3]))
+			if shader.Attributes&2 != 0 && !u3dAlphaTest(shader.AlphaFunction, color[3], float64(shader.AlphaReference)) {
+				continue
+			}
+			if pass.Attributes&1 != 0 {
+				position := u3dVector{(px - r.viewport[0] - r.viewport[2]/2 - r.camera.ShiftX) / r.camera.ScaleX, (r.viewport[1] + r.viewport[3]/2 + r.camera.ShiftY - py) / r.camera.ScaleY, depth}
+				if r.camera.Perspective {
+					position[0] *= depth
+					position[1] *= depth
+				}
+				distance := math.Hypot(math.Hypot(position[0], position[1]), position[2])
+				factor := (float64(pass.FogFar) - distance) / (float64(pass.FogFar) - float64(pass.FogNear))
+				if pass.FogMode != 0 {
+					amount := distance * math.Log(100) / float64(pass.FogFar)
+					if pass.FogMode == 2 {
+						amount *= amount
+					}
+					factor = math.Exp(-amount)
+				}
+				factor = min(1, max(0, factor))
+				for c := range 3 {
+					color[c] = color[c]*factor + float64(pass.FogColor[c])*(1-factor)
+				}
+			}
+			for c := range 3 {
+				color[c] = min(1, max(0, color[c]))
+			}
+			if err := r.fragment(pixel, depth, color, shader.Blend); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// fragment 直接保存不透明覆盖，透明及其他混合方式保留逐像素深度
+// 入参: pixel 像素索引, depth 深度, color 颜色, blend 混合方式
+// 返回: error 预算或取消错误
+func (r *u3dRender) fragment(pixel int, depth float64, color [4]float64, blend uint32) error {
+	if !finite(depth) {
+		return fmt.Errorf("invalid U3D fragment depth")
+	}
+	p := &r.frame[pixel]
+	if blend == 0x606 && color[3] == 1 || blend == 0x607 && color[3] == 0 {
+		p.depth = depth
+		p.order = r.order
+		copy(p.color[:], color[:3])
+		return nil
+	}
+	if blend == 0x606 && color[3] == 0 || blend == 0x607 && color[3] == 1 {
+		return nil
+	}
+	if r.fragments >= math.MaxInt32 {
+		return fmt.Errorf("U3D fragment count exceeds limit")
+	}
+	chunk := r.fragments / 512
+	if chunk == len(r.chunks) {
+		if err := r.reserve(1, 512*56+48); err != nil {
+			return err
+		}
+		r.chunks = append(r.chunks, make([]u3dFragment, 512))
+	}
+	r.chunks[chunk][r.fragments%512] = u3dFragment{color: color, depth: depth, order: r.order, blend: blend, next: p.head}
+	p.head = int32(r.fragments)
+	r.fragments++
+	return nil
+}
+
+// resolveFragments 按每个像素的远近排序，正确处理相交透明面和着色器叠加
+// 返回: error 预算或取消错误
+func (r *u3dRender) resolveFragments() error {
+	if r.fragments == 0 {
+		return r.ctx.Err()
+	}
+	get := func(i int) *u3dFragment { return &r.chunks[i/512][i%512] }
+	for i := range r.frame {
+		if i%1024 == 0 {
+			if err := r.ctx.Err(); err != nil {
+				return err
+			}
+		}
+		pixel := &r.frame[i]
+		r.scratch = r.scratch[:0]
+		for index := pixel.head; index >= 0; {
+			if len(r.scratch)%1024 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			current := int(index)
+			fragment := get(current)
+			index = fragment.next
+			if fragment.depth > pixel.depth || fragment.depth == pixel.depth && fragment.order < pixel.order {
+				continue
+			}
+			if len(r.scratch) == cap(r.scratch) {
+				capacity := max(8, cap(r.scratch)*2)
+				if err := r.reserve(uint64(capacity), 8); err != nil {
+					return err
+				}
+				values := make([]int, len(r.scratch), capacity)
+				copy(values, r.scratch)
+				r.remaining += uint64(cap(r.scratch)) * 8
+				r.scratch = values
+			}
+			r.scratch = append(r.scratch, current)
+		}
+		slices.SortFunc(r.scratch, func(a, b int) int {
+			x, y := get(a), get(b)
+			if x.depth > y.depth {
+				return -1
+			}
+			if x.depth < y.depth {
+				return 1
+			}
+			if x.order < y.order {
+				return -1
+			}
+			if x.order > y.order {
+				return 1
+			}
+			return 0
+		})
+		for layer, index := range r.scratch {
+			if layer%1024 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			fragment := get(index)
+			alpha := fragment.color[3]
+			if fragment.blend == 0x607 {
+				alpha = 1 - alpha
+			}
+			for c := range 3 {
+				switch fragment.blend {
+				case 0x604:
+					pixel.color[c] += fragment.color[c]
+				case 0x605:
+					pixel.color[c] *= fragment.color[c]
+				default:
+					pixel.color[c] = fragment.color[c]*alpha + pixel.color[c]*(1-alpha)
+				}
+				pixel.color[c] = min(1, max(0, pixel.color[c]))
+			}
+		}
+	}
+	return r.ctx.Err()
+}

ofdgo_u3d_view.go

@@ -0,0 +1,131 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"io"
+)
+
+// U3DView 保存视图节点的投影、裁剪、视口及叠加层参数
+type U3DView struct {
+	Attributes          uint32
+	Near, Far           float32
+	Projection          float32
+	ProjectionVector    [3]float32
+	Viewport            [4]float32
+	Backdrops, Overlays []U3DViewLayer
+}
+
+// U3DViewLayer 保存背景或覆盖纹理，注册点使用纹理像素，旋转使用弧度
+type U3DViewLayer struct {
+	Texture         string
+	Blend, Rotation float32
+	Location        [2]float32
+	Registration    [2]int32
+	Scale           [2]float32
+}
+
+// U3DViewResource 保存视图的绘制轮次，各轮独立指定根节点及雾效
+type U3DViewResource struct {
+	Name   string
+	Passes []U3DViewPass
+}
+
+// U3DViewPass 保存单轮根节点与雾效，Attributes最低位启用雾效
+type U3DViewPass struct {
+	Root                string
+	Attributes, FogMode uint32
+	FogColor            [4]float32
+	FogNear, FogFar     float32
+}
+
+// view 按ECMA-363第9.5.4节读取视图节点的可变投影字段
+// 入参: r 字段读取器
+// 返回: *U3DView 视图, error 结构或预算错误
+func (d *u3dDecoder) view(r *u3dValues) (*U3DView, error) {
+	view := &U3DView{Attributes: r.u32(), Near: r.f32(), Far: r.f32()}
+	if view.Attributes & ^uint32(7) != 0 {
+		return nil, fmt.Errorf("invalid U3D view attributes")
+	}
+	if view.Attributes&6 < 4 {
+		view.Projection = r.f32()
+	} else {
+		for i := range view.ProjectionVector {
+			view.ProjectionVector[i] = r.f32()
+		}
+	}
+	for i := range view.Viewport {
+		view.Viewport[i] = r.f32()
+	}
+	for _, layers := range []*[]U3DViewLayer{&view.Backdrops, &view.Overlays} {
+		count := r.u32()
+		if uint64(count) > uint64(len(r.data)-r.pos)/34 {
+			return nil, io.ErrUnexpectedEOF
+		}
+		if err := d.reserve(uint64(count), 64); err != nil {
+			return nil, err
+		}
+		*layers = make([]U3DViewLayer, int(count))
+		for i := range *layers {
+			if err := d.ctx.Err(); err != nil {
+				return nil, err
+			}
+			layer := &(*layers)[i]
+			layer.Texture = r.text()
+			layer.Blend, layer.Rotation = r.f32(), r.f32()
+			for j := range layer.Location {
+				layer.Location[j] = r.f32()
+			}
+			for j := range layer.Registration {
+				layer.Registration[j] = int32(r.u32())
+			}
+			for j := range layer.Scale {
+				layer.Scale[j] = r.f32()
+			}
+		}
+	}
+	return view, r.err
+}
+
+// viewResource 按ECMA-363第9.8.2节读取绘制轮次与雾效
+// 入参: r 字段读取器, name 资源名
+// 返回: error 结构或预算错误
+func (d *u3dDecoder) viewResource(r *u3dValues, name string) error {
+	count := r.u32()
+	if uint64(count) > uint64(len(r.data)-r.pos)/34 {
+		return io.ErrUnexpectedEOF
+	}
+	if err := d.reserve(uint64(count), 48); err != nil {
+		return err
+	}
+	view := U3DViewResource{Name: name, Passes: make([]U3DViewPass, int(count))}
+	for i := range view.Passes {
+		if err := d.ctx.Err(); err != nil {
+			return err
+		}
+		pass := &view.Passes[i]
+		pass.Root, pass.Attributes, pass.FogMode = r.text(), r.u32(), r.u32()
+		if pass.Attributes > 1 || pass.FogMode > 2 {
+			return fmt.Errorf("invalid U3D view fog parameters")
+		}
+		for j := range pass.FogColor {
+			pass.FogColor[j] = r.f32()
+		}
+		pass.FogNear, pass.FogFar = r.f32(), r.f32()
+	}
+	d.model.Views = append(d.model.Views, view)
+	return r.err
+}