Open CASCADE学习|分割曲线

1、通过参数进行分割

分别获得曲线的 FirstParameter 和 LastParameter ，然后对参数进行分割，获得n个ui，并对每个ui调用D0（获得这个点的坐标值）或D1（获得这个点的坐标值和切向量）。这个方法的优点是，简单易行，好操作，缺点均分参数轴获得的曲线的分割可能不是均匀的。

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#include"Viewer.h"
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int main(int argc, char* argv[])
{
    gp_Dir  Z(0.0, 0.0, 1.0);
    gp_Pnt center(0, 0, 0.0);
    gp_Pnt xr(0.5, 0, 0.0);
    gp_Pnt yr(0.0, 1.0, 0.0);
    gp_Pnt zr(0.0, 0.0, 7.0);
    gp_Ax2  wb(center, Z);
    gp_Circ  wbcircle(wb, 0.125 / 2);
    TopoDS_Edge wbe = BRepBuilderAPI_MakeEdge(wbcircle);
    TopoDS_Edge xline = BRepBuilderAPI_MakeEdge(center, xr);
    TopoDS_Edge yline = BRepBuilderAPI_MakeEdge(center, yr);
    TopoDS_Edge zline = BRepBuilderAPI_MakeEdge(center, zr);
    gp_Pnt p1(-5, 0, 0.0);
    gp_Pnt p2(5, 0, 0.0);
    gp_Ax2  sr(center, Z);
    gp_Circ  bcircle(sr, 5);
    Handle(Geom_TrimmedCurve) bc = GC_MakeArcOfCircle(bcircle, p1, p2, 0);
    TopoDS_Edge anEdge = BRepBuilderAPI_MakeEdge(bc);
    Standard_Integer splitN = 10;
    Standard_Real firstParam = bc->FirstParameter();
    Standard_Real lastParam = bc->LastParameter();
    Viewer vout(50, 50, 500, 500);
    for (Standard_Integer i = 0; i < splitN + 1; ++i)
    {
        Standard_Real ui = i * (lastParam - firstParam) / splitN;
        gp_Pnt pi;
        gp_Vec veci;
        bc->D1(ui, pi, veci);
        TopoDS_Vertex verti = BRepBuilderAPI_MakeVertex(pi);
        vout << verti;
    }
    vout << anEdge;
    vout << xline;
    vout << yline;
    vout << zline;
    vout.StartMessageLoop();
    return 0;
}
​

2、直接对曲线分割

通过类 GCPnts_UniformAbscissa 实现对一个Geom_Curve对象的平均分割，获得分割点的坐标及对应的参数，将坐标和参数存入一个列表中，供其他操作使用。

#include 
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#include 
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#include 
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#include"Viewer.h"
​
​
#include 
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​
​
int main(int argc, char* argv[])
{
    gp_Dir  Z(0.0, 0.0, 1.0);
    gp_Pnt center(0, 0, 0.0);
    gp_Pnt xr(0.5, 0, 0.0);
    gp_Pnt yr(0.0, 1.0, 0.0);
    gp_Pnt zr(0.0, 0.0, 7.0);
    gp_Ax2  wb(center, Z);
    gp_Circ  wbcircle(wb, 0.125 / 2);
    TopoDS_Edge wbe = BRepBuilderAPI_MakeEdge(wbcircle);
    TopoDS_Edge xline = BRepBuilderAPI_MakeEdge(center, xr);
    TopoDS_Edge yline = BRepBuilderAPI_MakeEdge(center, yr);
    TopoDS_Edge zline = BRepBuilderAPI_MakeEdge(center, zr);
    gp_Pnt p1(-5, 0, 0.0);
    gp_Pnt p2(5, 0, 0.0);
    gp_Ax2  sr(center, Z);
    gp_Circ  bcircle(sr, 5);
    Handle(Geom_TrimmedCurve) bc = GC_MakeArcOfCircle(bcircle, p1, p2, 0);
    TopoDS_Edge anEdge = BRepBuilderAPI_MakeEdge(bc);
    Standard_Integer splitN = 10;
    GeomAdaptor_Curve GAC(bc);
    GCPnts_UniformAbscissa UA(GAC, splitN + 1);
    gp_Pnt* pnts = new gp_Pnt[splitN + 1];
    Standard_Real* params = new Standard_Real[splitN + 1];
    Viewer vout(50, 50, 500, 500);
    if (UA.IsDone())
    {
        Standard_Real n = UA.NbPoints();
        Standard_Integer index = 0;
        for (; index < n + 1; index++)
        {
            Standard_Real parami = UA.Parameter(index + 1);
            params[index] = parami;
            gp_Pnt tpnt;
            bc->D0(parami, tpnt);
            pnts[index] = tpnt;
            TopoDS_Vertex verti = BRepBuilderAPI_MakeVertex(tpnt);
            vout << verti;
        }
    }
    vout << anEdge;
    vout << xline;
    vout << yline;
    vout << zline;
    vout.StartMessageLoop();
    return 0;
}
​