mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 13:56:32 +08:00
342 lines
9.4 KiB
Go
342 lines
9.4 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package threed
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import (
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"fmt"
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"math"
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)
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// u3dVector 保存计算过程中的三维双精度坐标
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type u3dVector [3]float64
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// u3dMatrix 保存按列排列的仿射矩阵
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type u3dMatrix [16]float64
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// 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
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type u3dInstance struct {
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node, parent int
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world u3dMatrix
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opacity float64
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visibility int8
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}
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// u3dIdentity 创建单位矩阵
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// 返回: u3dMatrix 单位矩阵
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func u3dIdentity() u3dMatrix { return u3dMatrix{1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1} }
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// multiply 连接子节点到父节点的变换
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// 入参: other 子变换
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// 返回: u3dMatrix 组合变换
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func (m u3dMatrix) multiply(other u3dMatrix) u3dMatrix {
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var result u3dMatrix
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for column := range 4 {
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for row := range 4 {
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for k := range 4 {
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result[column*4+row] += m[k*4+row] * other[column*4+k]
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}
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}
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}
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return result
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}
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// valid 判断矩阵是否为有限仿射变换
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// 返回: bool 是否可用于静态绘制
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func (m u3dMatrix) valid() bool {
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for _, v := range m {
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if !finite(v) {
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return false
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}
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}
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return m[3] == 0 && m[7] == 0 && m[11] == 0 && m[15] == 1
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}
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// point 将点从局部坐标映射到目标坐标
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// 入参: p 局部点
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// 返回: u3dVector 目标点
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func (m u3dMatrix) point(p u3dVector) u3dVector {
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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]}
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}
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// inverse 通过带主元消元计算仿射逆矩阵
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// 返回: u3dMatrix 逆矩阵, bool 是否存在有限逆矩阵
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func (m u3dMatrix) inverse() (u3dMatrix, bool) {
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if !m.valid() {
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return u3dMatrix{}, false
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}
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var rows [3][6]float64
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for i := range 3 {
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for j := range 3 {
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rows[i][j] = m[j*4+i]
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}
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rows[i][i+3] = 1
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}
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for column := range 3 {
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pivot := column
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for row := column + 1; row < 3; row++ {
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if math.Abs(rows[row][column]) > math.Abs(rows[pivot][column]) {
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pivot = row
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}
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}
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if rows[pivot][column] == 0 {
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return u3dMatrix{}, false
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}
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rows[pivot], rows[column] = rows[column], rows[pivot]
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divisor := rows[column][column]
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for j := range 6 {
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rows[column][j] /= divisor
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}
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for row := range 3 {
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if row != column {
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factor := rows[row][column]
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for j := range 6 {
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rows[row][j] -= factor * rows[column][j]
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}
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}
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}
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}
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result := u3dIdentity()
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for row := range 3 {
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for col := range 3 {
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result[col*4+row] = rows[row][col+3]
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}
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result[12+row] = -(result[row]*m[12] + result[4+row]*m[13] + result[8+row]*m[14])
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}
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return result, result.valid()
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}
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// normal 以逆矩阵的转置变换并归一化法线
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// 入参: n 局部法线，接收者为局部变换的逆矩阵
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// 返回: u3dVector 目标法线
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func (m u3dMatrix) normal(n u3dVector) u3dVector {
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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()
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}
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// unit 归一化向量，零向量保持为零
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// 返回: u3dVector 单位向量
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func (v u3dVector) unit() u3dVector {
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scale := max(math.Abs(v[0]), math.Abs(v[1]), math.Abs(v[2]))
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if scale == 0 || !finite(scale) {
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return u3dVector{}
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}
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for i := range v {
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v[i] /= scale
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}
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length := math.Sqrt(v.dot(v))
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return u3dVector{v[0] / length, v[1] / length, v[2] / length}
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}
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// sub 求向量差
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// 入参: other 被减向量
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// 返回: u3dVector 差向量
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func (v u3dVector) sub(other u3dVector) u3dVector {
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return u3dVector{v[0] - other[0], v[1] - other[1], v[2] - other[2]}
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}
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// dot 求向量内积
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// 入参: other 另一向量
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// 返回: float64 内积
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func (v u3dVector) dot(other u3dVector) float64 { return v[0]*other[0] + v[1]*other[1] + v[2]*other[2] }
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// cross 求向量叉积
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// 入参: other 另一向量
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// 返回: u3dVector 叉积
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func (v u3dVector) cross(other u3dVector) u3dVector {
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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]}
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}
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// 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
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// 入参: points 按绕序排列的顶点
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// 返回: u3dVector 单位法线，退化三角面返回零向量
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func u3dTriangleNormal(points [3]u3dVector) u3dVector {
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var normal u3dVector
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score := 0.0
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for i := range 3 {
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a := points[(i+1)%3].sub(points[i]).unit()
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b := points[(i+2)%3].sub(points[i]).unit()
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candidate := a.cross(b)
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if length := max(math.Abs(candidate[0]), math.Abs(candidate[1]), math.Abs(candidate[2])); length > score {
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normal, score = candidate, length
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}
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}
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return normal.unit()
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}
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// sceneGraph 校验父子关系并确定拓扑顺序，只有默认根的后代接入场景
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// 返回: []int 拓扑顺序, map[string]int 节点索引, error 结构、预算或取消错误
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func (r *Renderer) sceneGraph() ([]int, map[string]int, error) {
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nodes := r.model.Nodes
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if err := r.Reserve(uint64(len(nodes)), 161); err != nil {
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return nil, nil, err
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}
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index := make(map[string]int, len(nodes))
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for i, node := range nodes {
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if i%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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if _, exists := index[node.Name]; exists || node.Name == "" {
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return nil, nil, fmt.Errorf("invalid U3D render node name")
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}
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switch node.Kind {
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case "Group", "Model", "Light", "View":
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default:
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return nil, nil, fmt.Errorf("unsupported U3D render node kind")
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}
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index[node.Name] = i
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}
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counts := make([]int, len(nodes))
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children := make([][]int, len(nodes))
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r.byNode = make([][]int, len(nodes))
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r.connected = make([]bool, len(nodes))
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for i, node := range nodes {
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if err := r.Reserve(uint64(len(node.Parents)), 16); err != nil {
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return nil, nil, err
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}
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for k, parent := range node.Parents {
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if k%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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if j, ok := index[parent.Name]; ok {
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counts[i]++
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children[j] = append(children[j], i)
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}
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}
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}
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queue := make([]int, 0, len(nodes))
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for i, n := range counts {
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if i%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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if n == 0 {
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queue = append(queue, i)
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}
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}
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for cursor := 0; cursor < len(queue); cursor++ {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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i := queue[cursor]
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for j, parent := range nodes[i].Parents {
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if j%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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if parent.Name == "" {
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r.connected[i] = true
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break
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}
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if p, exists := index[parent.Name]; exists && r.connected[p] {
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r.connected[i] = true
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break
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}
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}
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for childIndex, child := range children[i] {
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if childIndex%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return nil, nil, err
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}
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}
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counts[child]--
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if counts[child] == 0 {
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queue = append(queue, child)
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}
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}
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}
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if len(queue) != len(nodes) {
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return nil, nil, fmt.Errorf("cyclic U3D node parents")
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}
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return queue, index, nil
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}
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// instances 按拓扑顺序展开接入场景的父路径，不将未解析的父节点视为默认根
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// 入参: order 拓扑顺序, index 节点索引, limit 最大实例数
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// 返回: error 变换、预算、实例上限或取消错误
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func (r *Renderer) instances(order []int, index map[string]int, limit int) error {
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nodes := r.model.Nodes
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for _, i := range order {
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if err := r.ctx.Err(); err != nil {
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return err
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}
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if !r.connected[i] {
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continue
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}
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state := r.states[nodes[i].Name]
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for parentIndex, parent := range nodes[i].Parents {
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if parentIndex%256 == 0 {
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if err := r.ctx.Err(); err != nil {
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return err
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}
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}
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parents := []int{-1}
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if parent.Name != "" {
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j, exists := index[parent.Name]
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if !exists || !r.connected[j] {
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continue
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}
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parents = r.byNode[j]
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}
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var local u3dMatrix
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for k, v := range parent.Transform {
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local[k] = float64(v)
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}
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if animation, exists := r.animated[nodes[i].Name]; exists {
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local = local.multiply(animation.matrix)
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}
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if state.Matrix != nil {
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local = *state.Matrix
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}
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if !local.valid() {
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return fmt.Errorf("unsupported U3D non-affine node transform")
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}
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for _, p := range parents {
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if len(r.scene) >= limit {
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return fmt.Errorf("U3D instance count exceeds limit")
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}
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if err := r.Reserve(1, 384); err != nil {
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return err
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}
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world := local
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opacity, visibility := -1.0, int8(-1)
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if p >= 0 {
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world = r.scene[p].world.multiply(local)
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opacity, visibility = r.scene[p].opacity, r.scene[p].visibility
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}
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if state.Opacity != nil {
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opacity = *state.Opacity
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}
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if state.Visible != nil {
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visibility = 0
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if *state.Visible {
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visibility = 1
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}
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}
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if !world.valid() {
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return fmt.Errorf("invalid U3D world transform")
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}
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r.byNode[i] = append(r.byNode[i], len(r.scene))
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r.scene = append(r.scene, u3dInstance{node: i, parent: p, world: world, opacity: opacity, visibility: visibility})
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}
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}
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}
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return r.ctx.Err()
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}
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