57 lines
1.9 KiB
Markdown
57 lines
1.9 KiB
Markdown
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# VDE-019: make_box/make_cylinder/make_sphere 不支持位置偏移参数
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- **ID**: VDE-019
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- **Date**: 2026-07-28
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- **Status**: Fixed
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- **Severity**: Medium
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- **Category**: API Gap
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- **Source**: ViewDesign feat/viewdesign-engine branch
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## Issue
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VDE 的基本体 API 仅支持原点为中心的创建，缺少位置偏移参数：
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```cpp
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// VDE 当前 API（仅原点）
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auto box = vde::brep::make_box(10, 5, 3); // 原点中心
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auto sph = vde::brep::make_sphere(5.0); // 原点中心
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auto cyl = vde::brep::make_cylinder(2.0, 10.0); // 原点中心，Y 轴
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```
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ViewDesign 的 `PrimitiveFactory` 需要任意位置的基本体构建：
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```cpp
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Shape box(double x1, y1, z1, x2, y2, z2); // 任意两点定义的盒子
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Shape sphere(double cx, cy, cz, radius); // 任意位置球体
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Shape cylinder(double cx, cy, cz, radius, height); // 任意位置圆柱
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```
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## Current Workaround (ViewDesign)
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通过 BrepModel → mesh 转换后手动偏移顶点坐标：
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```cpp
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auto model = vde::brep::make_sphere(radius);
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// 转换为 mesh，然后遍历顶点加偏移
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brepToMeshData(model, verts, tris);
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for (size_t i = 0; i < verts.size(); i += 3) {
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verts[i] += offX; verts[i+1] += offY; verts[i+2] += offZ;
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}
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```
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此方案是 lossy 的（B-Rep 精度退化为 mesh 精度），但对于基本体生成可接受。
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## Suggested Fix
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为 VDE 的 `make_box`/`make_sphere`/`make_cylinder` 添加可选的位置偏移参数：
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```cpp
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BrepModel make_box(double w, double h, double d,
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const Point3D& center = Point3D(0, 0, 0));
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BrepModel make_sphere(double radius,
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const Point3D& center = Point3D(0, 0, 0));
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BrepModel make_cylinder(double radius, double height,
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const Point3D& center = Point3D(0, 0, 0));
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```
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或者提供 `make_box(double x1, y1, z1, x2, y2, z2)` 两点定义的重载。
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