Open CASCADE學習|實現裁剪操作

1. 引言

Open CASCADE (簡稱OCC) 是一個功能強大的開源幾何建模內核，廣泛應用于CAD/CAM/CAE領域。裁剪操作作為幾何建模中的基礎功能，在模型編輯、布爾運算、幾何分析等方面有著重要作用。本文將全面探討Open CASCADE中的裁剪操作實現原理、應用場景及具體實現方法。

2. 裁剪操作基礎

2.1 裁剪操作類型

Open CASCADE主要支持以下幾種裁剪操作：

布爾裁剪(BRepAlgoAPI_Cut)
面域裁剪
曲線裁剪
高級裁剪(如帶公差裁剪)

2.2 核心類介紹

實現裁剪操作主要涉及以下核心類：

BRepAlgoAPI_Cut：布爾裁剪操作
BRepAlgoAPI_Splitter：分割操作
BRepBuilderAPI_MakeEdge：邊構建
Geom_TrimmedCurve：曲線裁剪

3. 實體裁剪實現

3.1 基本立方體裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <TopoDS_Shape.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 創建第一個立方體 (10x10x10)TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();// 創建第二個立方體 (5x5x15)，與第一個立方體部分重疊TopoDS_Shape box2 = BRepPrimAPI_MakeBox(5., 5., 15.).Shape();// 執行裁剪操作：box1 剪去 box2BRepAlgoAPI_Cut cutter(box1, box2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失敗" << std::endl;return 1;}// 獲取結果形狀TopoDS_Shape result = cutter.Shape();// 保存結果BRepTools::Write(result, "box_cut_result.brep");std::cout << "立方體裁剪完成，結果已保存為 box_cut_result.brep" << std::endl;return 0;
}

3.2 復雜形狀裁剪

#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()
{// 創建圓柱體gp_Ax2 cylinderAxis(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1));TopoDS_Shape cylinder = BRepPrimAPI_MakeCylinder(cylinderAxis, 3., 10.).Shape();// 創建球體TopoDS_Shape sphere = BRepPrimAPI_MakeSphere(gp_Pnt(0, 0, 5), 2.).Shape();// 執行裁剪操作BRepAlgoAPI_Cut cutter(cylinder, sphere);if (!cutter.IsDone()) {std::cerr << "裁剪操作失敗" << std::endl;return 1;}// 獲取結果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "cylinder_cut_sphere.brep");std::cout << "復雜形狀裁剪完成，結果已保存" << std::endl;return 0;
}

4. 曲線與直線裁剪

4.1 直線重合部分裁剪

#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()
{// 創建第一條直線 (沿X軸，從(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(); // 參數范圍0-10// 創建第二條直線 (與第一條部分重合，從(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(); // 參數范圍0-10// 將邊轉換為線（Wire）以便進行布爾操作BRepBuilderAPI_MakeWire wireMaker1(edge1);BRepBuilderAPI_MakeWire wireMaker2(edge2);// 執行裁剪操作：wire1 減去 wire2（重合部分）BRepAlgoAPI_Cut cutter(wireMaker1, wireMaker2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失敗" << std::endl;return;}// 獲取結果（應該是從(0,0,0)到(5,0,0)的線段）TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "cut_overlapping_lines.brep");std::cout << "重合部分裁剪完成，結果已保存" << std::endl;
}
int main()
{CutOverlappingLines();return 0;
}

4.2 直線相交裁剪

#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()
{// 創建第一條直線 (沿X軸)gp_Lin line1(gp_Pnt(0, 0, 0), gp_Dir(1, 0, 0));TopoDS_Edge edge1 = BRepBuilderAPI_MakeEdge(line1, 0, 10).Edge();// 創建第二條直線 (與第一條在(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();// 計算交點BRepExtrema_DistShapeShape distSS(edge1, edge2);if (distSS.NbSolution() == 0 || distSS.Value() > Precision::Confusion()) {std::cerr << "直線不相交" << std::endl;return 1;}// 獲取交點gp_Pnt intersection = distSS.PointOnShape1(1);TopoDS_Vertex vertex = BRepBuilderAPI_MakeVertex(intersection).Vertex();// 使用新版Splitter APIBRepAlgoAPI_Splitter splitter;// 添加要分割的形狀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 << "分割操作失敗" << std::endl;return 1;}// 獲取分割結果const TopoDS_Shape& splitResult = splitter.Shape();// 輸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 << "線段 " << segmentCount + 1 << ": 從 ("<< start.X() << "," << start.Y() << "," << start.Z()<< ") 到 ("<< end.X() << "," << end.Y() << "," << end.Z() << ")" << std::endl;}// 保存結果BRepTools::Write(splitResult, "split_lines_result.brep");std::cout << "直線相交裁剪完成，共得到 " << segmentCount << " 條線段" << std::endl;return 0;
}

5. 高級裁剪技術

5.1 帶公差裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepTools.hxx>
#include <BOPAlgo_Options.hxx>
#include <iostream>
#include <TopTools_ListOfShape.hxx>int main()
{// 創建兩個幾乎接觸但不完全相交的立方體TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();TopoDS_Shape box2 = BRepPrimAPI_MakeBox(9.99, 9.99, 15.).Shape();// 創建形狀列表TopTools_ListOfShape args;args.Append(box1);TopTools_ListOfShape tools;tools.Append(box2);// 創建裁剪操作并設置公差BRepAlgoAPI_Cut cutter;cutter.SetArguments(args);cutter.SetTools(tools);cutter.SetFuzzyValue(0.02); // 設置2%的公差cutter.Build();if (!cutter.IsDone()) {std::cerr << "裁剪操作失敗" << std::endl;return 1;}// 獲取結果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "fuzzy_cut_result.brep");std::cout << "帶公差裁剪完成" << std::endl;return 0;
}

5.2 多對象裁剪

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepPrimAPI_MakeSphere.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <TopTools_ListOfShape.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 創建基礎形狀TopoDS_Shape base = BRepPrimAPI_MakeBox(20., 20., 20.).Shape();// 創建多個裁剪工具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());// 執行多對象裁剪BRepAlgoAPI_Cut cutter;TopTools_ListOfShape baseList;baseList.Append(base); // 將基礎形狀添加到列表中cutter.SetArguments(baseList); // 使用列表作為參數cutter.SetTools(tools);cutter.Build();if (!cutter.IsDone()) {std::cerr << "多對象裁剪失敗" << std::endl;return 1;}// 獲取結果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "multi_cut_result.brep");std::cout << "多對象裁剪完成" << std::endl;return 0;
}

6. 性能優化與錯誤處理

6.1 裁剪操作驗證

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepCheck_Analyzer.hxx>
#include <BRepTools.hxx>
#include <iostream>int main()
{// 創建兩個立方體TopoDS_Shape box1 = BRepPrimAPI_MakeBox(10., 10., 10.).Shape();TopoDS_Shape box2 = BRepPrimAPI_MakeBox(5., 5., 5.).Shape();// 執行裁剪BRepAlgoAPI_Cut cutter(box1, box2);if (!cutter.IsDone()) {std::cerr << "裁剪操作失敗" << std::endl;if (cutter.HasErrors()) {cutter.DumpErrors(std::cerr);}return 1;}// 驗證結果TopoDS_Shape result = cutter.Shape();BRepCheck_Analyzer analyzer(result);if (!analyzer.IsValid()) {std::cerr << "裁剪結果無效" << std::endl;return 1;}// 保存有效結果BRepTools::Write(result, "validated_cut.brep");std::cout << "已驗證的裁剪操作完成" << std::endl;return 0;
}

6.2 并行裁剪優化

#include <BRepPrimAPI_MakeBox.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepTools.hxx>
#include <OSD_Parallel.hxx>
#include <TopTools_ListOfShape.hxx>
#include <iostream>int main()
{// 啟用并行處理OSD_Parallel::SetUseOcctThreads(Standard_True);// 創建復雜形狀TopoDS_Shape complexShape = BRepPrimAPI_MakeBox(100., 100., 100.).Shape();TopoDS_Shape cuttingTool = BRepPrimAPI_MakeBox(90., 90., 90.).Shape();// 創建形狀列表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); // 啟用并行cutter.Build();if (!cutter.IsDone()) {std::cerr << "并行裁剪失敗" << std::endl;return 1;}// 獲取結果TopoDS_Shape result = cutter.Shape();BRepTools::Write(result, "parallel_cut.brep");std::cout << "并行裁剪完成" << std::endl;return 0;
}