Open CASCADE学习|实现裁剪操作

1. 引言

Open CASCADE (简称OCC) 是一个功能强大的开源几何建模内核，广泛应用于CAD/CAM/CAE领域。裁剪操作作为几何建模中的基础功能，在模型编辑、布尔运算、几何分析等方面有着重要作用。本文将全面探讨Open CASCADE中的裁剪操作实现原理、应用场景及具体实现方法。

2. 裁剪操作基础

2.1 裁剪操作类型

Open CASCADE主要支持以下几种裁剪操作：

布尔裁剪(BRepAlgoAPI_Cut)
面域裁剪
曲线裁剪
高级裁剪(如带公差裁剪)

2.2 核心类介绍

实现裁剪操作主要涉及以下核心类：

BRepAlgoAPI_Cut：布尔裁剪操作
BRepAlgoAPI_Splitter：分割操作
BRepBuilderAPI_MakeEdge：边构建
Geom_TrimmedCurve：曲线裁剪

3. 实体裁剪实现

3.1 基本立方体裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <TopoDS_Shape.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 创建第一个立方体 (10x10x10)TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();// 创建第二个立方体 (5x5x15)，与第一个立方体部分重叠TopoDS_Shape box2 = BRepPrimAPI_MakeBox(5., 5., 15.).Shape();// 执行裁剪操作：box1 剪去 box2BRepAlgoAPI_Cut cutter(box1, box2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失败" << std::endl;return 1;}// 获取结果形状TopoDS_Shape result = cutter.Shape();// 保存结果BRepTools::Write(result, "box_cut_result.brep");std::cout << "立方体裁剪完成，结果已保存为 box_cut_result.brep" << std::endl;return 0;
}

3.2 复杂形状裁剪

#include <BRepPrimAPI_MakeCylinder.hxx>
#include <BRepPrimAPI_MakeSphere.hxx>
#include <gp_Ax2.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <TopoDS_Shape.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 创建圆柱体gp_Ax2 cylinderAxis(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1));TopoDS_Shape cylinder = BRepPrimAPI_MakeCylinder(cylinderAxis, 3., 10.).Shape();// 创建球体TopoDS_Shape sphere = BRepPrimAPI_MakeSphere(gp_Pnt(0, 0, 5), 2.).Shape();// 执行裁剪操作BRepAlgoAPI_Cut cutter(cylinder, sphere);if (!cutter.IsDone()) {std::cerr << "裁剪操作失败" << std::endl;return 1;}// 获取结果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "cylinder_cut_sphere.brep");std::cout << "复杂形状裁剪完成，结果已保存" << std::endl;return 0;
}

4. 曲线与直线裁剪

4.1 直线重合部分裁剪

#include <gp_Lin.hxx>
#include <TopoDS_Edge.hxx>
#include <BRepBuilderAPI_MakeEdge.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepTools.hxx>
#include <BRepBuilderAPI_MakeWire.hxx>void CutOverlappingLines()
{// 创建第一条直线 (沿X轴，从(0,0,0)到(10,0,0))gp_Lin line1(gp_Pnt(0, 0, 0), gp_Dir(1, 0, 0));TopoDS_Edge edge1 = BRepBuilderAPI_MakeEdge(line1, 0, 10).Edge(); // 参数范围0-10// 创建第二条直线 (与第一条部分重合，从(5,0,0)到(15,0,0))gp_Lin line2(gp_Pnt(5, 0, 0), gp_Dir(1, 0, 0));TopoDS_Edge edge2 = BRepBuilderAPI_MakeEdge(line2, 0, 10).Edge(); // 参数范围0-10// 将边转换为线（Wire）以便进行布尔操作BRepBuilderAPI_MakeWire wireMaker1(edge1);BRepBuilderAPI_MakeWire wireMaker2(edge2);// 执行裁剪操作：wire1 减去 wire2（重合部分）BRepAlgoAPI_Cut cutter(wireMaker1, wireMaker2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失败" << std::endl;return;}// 获取结果（应该是从(0,0,0)到(5,0,0)的线段）TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "cut_overlapping_lines.brep");std::cout << "重合部分裁剪完成，结果已保存" << std::endl;
}
int main()
{CutOverlappingLines();return 0;
}

4.2 直线相交裁剪

#include <gp_Lin.hxx>
#include <TopoDS_Edge.hxx>
#include <BRepBuilderAPI_MakeEdge.hxx>
#include <BRepExtrema_DistShapeShape.hxx>
#include <BRepBuilderAPI_MakeVertex.hxx>
#include <BRepAlgoAPI_Splitter.hxx>
#include <TopTools_ListOfShape.hxx>
#include <TopExp_Explorer.hxx>
#include <BRep_Tool.hxx>
#include <Geom_Curve.hxx>
#include <Precision.hxx>
#include <BRepTools.hxx>
#include <TopoDS.hxx>
#include <iostream>int main()
{// 创建第一条直线 (沿X轴)gp_Lin line1(gp_Pnt(0, 0, 0), gp_Dir(1, 0, 0));TopoDS_Edge edge1 = BRepBuilderAPI_MakeEdge(line1, 0, 10).Edge();// 创建第二条直线 (与第一条在(5,0,0)相交)gp_Lin line2(gp_Pnt(5, -5, 0), gp_Dir(0, 1, 0));TopoDS_Edge edge2 = BRepBuilderAPI_MakeEdge(line2, 0, 10).Edge();// 计算交点BRepExtrema_DistShapeShape distSS(edge1, edge2);if (distSS.NbSolution() == 0 || distSS.Value() > Precision::Confusion()) {std::cerr << "直线不相交" << std::endl;return 1;}// 获取交点gp_Pnt intersection = distSS.PointOnShape1(1);TopoDS_Vertex vertex = BRepBuilderAPI_MakeVertex(intersection).Vertex();// 使用新版Splitter APIBRepAlgoAPI_Splitter splitter;// 添加要分割的形状TopTools_ListOfShape shapesToSplit;shapesToSplit.Append(edge1);splitter.SetArguments(shapesToSplit);// 添加分割工具TopTools_ListOfShape splitTools;splitTools.Append(vertex);splitter.SetTools(splitTools);splitter.Build();if (!splitter.IsDone()) {std::cerr << "分割操作失败" << std::endl;return 1;}// 获取分割结果const TopoDS_Shape& splitResult = splitter.Shape();// 输出分割后的各段信息TopExp_Explorer exp(splitResult, TopAbs_EDGE);int segmentCount = 0;for (; exp.More(); exp.Next(), segmentCount++) {TopoDS_Edge segment = TopoDS::Edge(exp.Current());double first, last;Handle(Geom_Curve) curve = BRep_Tool::Curve(segment, first, last);gp_Pnt start = curve->Value(first);gp_Pnt end = curve->Value(last);std::cout << "线段 " << segmentCount + 1 << ": 从 ("<< start.X() << "," << start.Y() << "," << start.Z()<< ") 到 ("<< end.X() << "," << end.Y() << "," << end.Z() << ")" << std::endl;}// 保存结果BRepTools::Write(splitResult, "split_lines_result.brep");std::cout << "直线相交裁剪完成，共得到 " << segmentCount << " 条线段" << std::endl;return 0;
}

5. 高级裁剪技术

5.1 带公差裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepTools.hxx>
#include <BOPAlgo_Options.hxx>
#include <iostream>
#include <TopTools_ListOfShape.hxx>int main()
{// 创建两个几乎接触但不完全相交的立方体TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();TopoDS_Shape box2 = BRepPrimAPI_MakeBox(9.99, 9.99, 15.).Shape();// 创建形状列表TopTools_ListOfShape args;args.Append(box1);TopTools_ListOfShape tools;tools.Append(box2);// 创建裁剪操作并设置公差BRepAlgoAPI_Cut cutter;cutter.SetArguments(args);cutter.SetTools(tools);cutter.SetFuzzyValue(0.02); // 设置2%的公差cutter.Build();if (!cutter.IsDone()) {std::cerr << "裁剪操作失败" << std::endl;return 1;}// 获取结果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "fuzzy_cut_result.brep");std::cout << "带公差裁剪完成" << std::endl;return 0;
}

5.2 多对象裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepPrimAPI_MakeSphere.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <TopTools_ListOfShape.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 创建基础形状TopoDS_Shape base = BRepPrimAPI_MakeBox(20., 20., 20.).Shape();// 创建多个裁剪工具TopTools_ListOfShape tools;tools.Append(BRepPrimAPI_MakeSphere(gp_Pnt(5, 5, 5), 3.).Shape());tools.Append(BRepPrimAPI_MakeSphere(gp_Pnt(15, 15, 15), 4.).Shape());tools.Append(BRepPrimAPI_MakeBox(10., 10., 2.).Shape());// 执行多对象裁剪BRepAlgoAPI_Cut cutter;TopTools_ListOfShape baseList;baseList.Append(base); // 将基础形状添加到列表中cutter.SetArguments(baseList); // 使用列表作为参数cutter.SetTools(tools);cutter.Build();if (!cutter.IsDone()) {std::cerr << "多对象裁剪失败" << std::endl;return 1;}// 获取结果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "multi_cut_result.brep");std::cout << "多对象裁剪完成" << std::endl;return 0;
}

6. 性能优化与错误处理

6.1 裁剪操作验证

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepCheck_Analyzer.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 创建两个立方体TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();TopoDS_Shape box2 = BRepPrimAPI_MakeBox(5., 5., 5.).Shape();// 执行裁剪BRepAlgoAPI_Cut cutter(box1, box2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失败" << std::endl;if (cutter.HasErrors()) {cutter.DumpErrors(std::cerr);}return 1;}// 验证结果TopoDS_Shape result = cutter.Shape();BRepCheck_Analyzer analyzer(result);if (!analyzer.IsValid()) {std::cerr << "裁剪结果无效" << std::endl;return 1;}// 保存有效结果BRepTools::Write(result, "validated_cut.brep");std::cout << "已验证的裁剪操作完成" << std::endl;return 0;
}

6.2 并行裁剪优化

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepTools.hxx>
#include <OSD_Parallel.hxx>
#include <TopTools_ListOfShape.hxx>
#include <iostream>int main()
{// 启用并行处理OSD_Parallel::SetUseOcctThreads(Standard_True);// 创建复杂形状TopoDS_Shape complexShape = BRepPrimAPI_MakeBox(100., 100., 100.).Shape();TopoDS_Shape cuttingTool = BRepPrimAPI_MakeBox(90., 90., 90.).Shape();// 创建形状列表TopTools_ListOfShape argumentShapes;argumentShapes.Append(complexShape);TopTools_ListOfShape toolShapes;toolShapes.Append(cuttingTool);// 配置并行裁剪BRepAlgoAPI_Cut cutter;cutter.SetArguments(argumentShapes);cutter.SetTools(toolShapes);cutter.SetRunParallel(Standard_True); // 启用并行cutter.Build();if (!cutter.IsDone()) {std::cerr << "并行裁剪失败" << std::endl;return 1;}// 获取结果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "parallel_cut.brep");std::cout << "并行裁剪完成" << std::endl;return 0;
}