Open Cascade中的布尔操作
Modeling Algorithms Boolean Operations
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布尔操作（Boolean Operations）是通过两个形状（S1，S2）的组合来生成新的形状。布尔操作有如下几种类型：
u 并集操作Fusion：Gets all the points in S1 or S2;
u 交集操作Common：Gets all the points in S1 and S2;
u 差集操作Cut S1 by S2：Gets all the points in S1 and not in S2;
下图所示为三种布尔操作：
1. BRepAlgoAPI_BooleanOperation
类BRepAlgoAPI_BooleanOperation是布尔操作的基类。
2. BRepAlgoAPI_Fuse
类BRepAlgoAPI_Fuse执行布尔并集操作。如下所示：
TopoDS_Shape theBox1 = BRepPrimAPI_MakeBox(50,200,70);
TopoDS_Shape theBox2 = BRepPrimAPI_MakeBox(-30,150,70);
TopoDS_Shape FusedShape = BRepAlgoAPI_Fuse(theBox1,theBox2);
Fuse two boxes
3. BRepAlgoAPI_Common
类BRepAlgoAPI_Common执行布尔交集操作，如下所示：
gp_Ax2 axe(gp_Pnt(10,10,10),gp_Dir(1,2,1));
TopoDS_Shape theBox = BRepPrimAPI_MakeBox(axe,60,80,100);
TopoDS_Shape theWedge = BRepPrimAPI_MakeWedge(60.,100.,80.,20.);
TopoDS_Shape theCommonSurface = BRepAlgoAPI_Common(theBox,theWedge);
Compute the common surface
4. BRepAlgoAPI_Cut
类BRepAlgoAPI_Cut执行布尔差集操作，如下所示：
TopoDS_Shape theBox = BRepPrimAPI_MakeBox(200,40,40);
TopoDS_Shape theSphere = BRepPrimAPI_MakeSphere(gp_Pnt(100,20,20),80);
TopoDS_Shape ShapeCut = BRepAlgoAPI_Cut(theSphere,theBox);
5. BRepAlgoAPI_Section