feat(文件拆分): 拆分几何三维基础能力

internal/base/threed/u3d_state.go

@@ -0,0 +1,120 @@
+// 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 threed
+
+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
+// 显式Opacity覆盖材质和纹理合成的透明度，之后仍应用视图附加透明度
+// 未匹配的名称不影响场景，Matrix和Motion均为空时保留每条父路径的原始变换
+// Motion以指定轨道替换节点变换，与Matrix互斥，不驱动骨架；显式变换优先于动画修饰器
+// Bones覆盖动画求值后的指定骨骼姿态，未指定项沿用当前局部变换，不修改共享几何
+type U3DNodeState struct {
+	Name    string
+	Opacity *float64
+	Visible *bool
+	Matrix  *[16]float64
+	Motion  *U3DTrackState
+	Bones   []U3DBoneState
+}
+
+// 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: groups 按优先级递增排列的节点覆盖分组
+// 返回: error 数值、预算或取消错误
+func (r *Renderer) nodeStates(groups ...[]U3DNodeState) error {
+	var count uint64
+	for _, states := range groups {
+		if uint64(len(states)) > ^uint64(0)-count {
+			return fmt.Errorf("U3D node state count exceeds limit")
+		}
+		count += uint64(len(states))
+	}
+	if count == 0 {
+		return nil
+	}
+	if err := r.Reserve(count, 160); err != nil {
+		return err
+	}
+	r.states = make(map[string]U3DNodeState, int(count))
+	for _, states := range groups {
+		for i, state := range states {
+			if i%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return err
+				}
+			}
+			r.states[state.Name] = state
+		}
+	}
+	var samples map[U3DTrackState]*[16]float64
+	defer func() {
+		if samples != nil {
+			r.remaining += 1024 + uint64(len(samples))*192
+		}
+	}()
+	for name, 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")
+		}
+		if state.Motion != nil {
+			if state.Matrix != nil || !finite(state.Motion.Time) {
+				return fmt.Errorf("invalid U3D node motion state")
+			}
+			if samples == nil {
+				if err := r.Reserve(1, 1024); err != nil {
+					return err
+				}
+				samples = make(map[U3DTrackState]*[16]float64)
+			}
+			matrix := samples[*state.Motion]
+			if matrix == nil {
+				if err := r.Reserve(1, 320); err != nil {
+					return err
+				}
+				value, err := r.trackMatrix(*state.Motion)
+				if err != nil {
+					return err
+				}
+				matrix = &value
+				samples[*state.Motion] = matrix
+			}
+			state.Matrix = matrix
+			r.states[name] = state
+		}
+	}
+	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
+}