feat(文件拆分): 拆分PDF格式适配模块

internal/codec/pdf/threed_section.go

@@ -0,0 +1,71 @@
+// 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 pdf
+
+import (
+	"context"
+	"fmt"
+	"math"
+
+	basethreed "github.com/xiaoqidun/ofdgo/internal/base/threed"
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// threeDSections 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 threeDSections(ctx context.Context, sections []pdfgo.ThreeDCrossSection, options *basethreed.U3DRenderOptions) error {
+	if len(sections) == 0 {
+		return nil
+	}
+	limit := options.MaxMemoryBytes
+	if limit == 0 {
+		limit = basethreed.DefaultBytes
+	}
+	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([]basethreed.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 := basethreed.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
+}