feat(文件拆分): 拆分几何三维基础能力

internal/base/threed/u3d_depth.go

@@ -0,0 +1,75 @@
+// 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"
+	"math"
+)
+
+// DepthRange 计算可见模型几何的相机深度范围，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 *Renderer) 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 := range len(mesh.Faces) + len(mesh.Lines) + len(mesh.Points) {
+			_, corners := mesh.primitive(j)
+			if j%256 == 0 {
+				if err := r.ctx.Err(); err != nil {
+					return 0, 0, false, err
+				}
+			}
+			for _, corner := range 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
+}