oce_bspline_surf_section.cxx

#include <stdlib.h>

#include <TColgp_Array2OfPnt.hxx>
#include <TColStd_Array1OfReal.hxx>
#include <TColStd_Array1OfInteger.hxx>

#include <gp_Pnt.hxx>
#include <TopoDS_Edge.hxx>
#include <BRepBuilderAPI_MakeEdge.hxx>
#include <TopoDS_Wire.hxx>
#include <BRepBuilderAPI_MakeWire.hxx>
#include <TopoDS_Face.hxx>
#include <BRepBuilderAPI_MakeFace.hxx>

#include <Geom_BSplineSurface.hxx>

#include <BRepBuilderAPI_Sewing.hxx>

#include <BRepAlgoAPI_Section.hxx>

int main(void)
{
    int udeg = 2, vdeg = 2;

    // Create Bezier surface
    TColgp_Array2OfPnt poles(1, 3, 1, 3);
    poles(1, 1) = gp_Pnt(0.0, 0.0, 0.0);
    poles(2, 1) = gp_Pnt(0.5, 0.0, 0.0);
    poles(3, 1) = gp_Pnt(1.0, 0.0, 0.0);
    poles(1, 2) = gp_Pnt(0.0, 0.5, 0.5);
    poles(2, 2) = gp_Pnt(0.5, 0.5, 0.5);
    poles(3, 2) = gp_Pnt(1.0, 0.5, 0.2);
    poles(1, 3) = gp_Pnt(0.0, 1.0, 0.0);
    poles(2, 3) = gp_Pnt(0.5, 1.0, 0.0);
    poles(3, 3) = gp_Pnt(1.0, 1.0, 0.0);

    // Length of uknots and umults has to be same
    // Same rule is for vknots and vmults
    int uknot_len = 2, umult_len = 2;
    int vknot_len = 2, vmult_len = 2;

    // Create arrays of U and V knots ...
    TColStd_Array1OfReal uknots(1, uknot_len);
    TColStd_Array1OfReal vknots(1, uknot_len);
    // ... and fill them with values
    uknots.SetValue(1, 0.0);
    uknots.SetValue(2, 1.0);
    vknots.SetValue(1, 0.0);
    vknots.SetValue(2, 1.0);

    // Create array of U and V multiplicities   
    TColStd_Array1OfInteger umults(1, umult_len);
    TColStd_Array1OfInteger vmults(1, vmult_len);

    // First and last multiplicities are set to udeg + 1 (vdeg respectively),
    // because we want main curves to start and finish on the first and
    // the last points
    umults.SetValue(1, udeg + 1);
    umults.SetValue(2, udeg + 1);
    vmults.SetValue(1, vdeg + 1);
    vmults.SetValue(2, vdeg + 1);

    Geom_BSplineSurface *surf= new Geom_BSplineSurface(poles, uknots, vknots, umults, vmults, udeg, vdeg, Standard_False, Standard_False);

    // Create Sewing at the first time
    BRepBuilderAPI_Sewing sewing;

    // Create points
    gp_Pnt point0 = gp_Pnt(0.25, 0.25, -1.0);
    gp_Pnt point1 = gp_Pnt(0.75, 0.25, -1.0);
    gp_Pnt point2 = gp_Pnt(0.75, 0.25,  1.0);
    gp_Pnt point3 = gp_Pnt(0.25, 0.25,  1.0);

    // Create edges
    TopoDS_Edge edge0 = BRepBuilderAPI_MakeEdge(point0, point1);
    TopoDS_Edge edge1 = BRepBuilderAPI_MakeEdge(point1, point2);
    TopoDS_Edge edge2 = BRepBuilderAPI_MakeEdge(point2, point3);
    TopoDS_Edge edge3 = BRepBuilderAPI_MakeEdge(point3, point0);

    // Create Wire
    TopoDS_Wire wire = BRepBuilderAPI_MakeWire(edge0, edge1, edge2, edge3);

    // Create Face
    TopoDS_Face face = BRepBuilderAPI_MakeFace(wire);

    // Add face to sewing
    sewing.Add(face);

    BRepAlgoAPI_Section(surf, sewing.SewedShape());

    return EXIT_SUCCESS;
}