Open CASCADE学习|遍历曲面的边
目录
1、球面的Brep数据
2、C++遍历球面的边
这里以球面为例来说明如何遍历曲面的边。
1、球面的Brep数据
使用Tcl命令在Draw Test Harness中生成的球面并到出Brep数据如下：
pload ALL
psphere asphere 1
dump asphere
结果如下：
*********** Dump of asphere *************
Shape : 9, FORWARD
Dump of 9 TShapes
-----------------
Flags : Free, Modified, Checked, Orientable, Closed, Infinite, Convex, Locked
TShape # 1 : SOLID 11000000 0000018AE4364B70
+2
TShape # 2 : SHELL 01011000 0000018AE43648F0
+3
TShape # 3 : FACE 01110000 0000018AE420C530
+4
Tolerance : 1e-07
- Surface : 1
TShape # 4 : WIRE 01011000 0000018AE4364270
-8 +6 +5 -6
TShape # 5 : EDGE 01010000 0000018AE3048880
+7 -7
Tolerance : 1e-07
same parametrisation of curves
same range on curves
degenerated
- PCurve : 4 on surface 1, range : 0 6.28318530717959
UV Points : 0, -1.5707963267949 6.28318530717959, -1.5707963267949
TShape # 6 : EDGE 01010000 0000018AE3049CC0
-9 +7
Tolerance : 1e-07
same parametrisation of curves
same range on curves
- Curve 3D : 1, range : 4.71238898038469 7.85398163397448
- PCurve : 2, 3 (CN) on surface 1, range : 4.71238898038469 7.85398163397448
UV Points : 6.28318530717959, -1.5707963267949 6.28318530717959, 1.5707963267949
UV Points : 0, -1.5707963267949 0, 1.5707963267949
TShape # 7 : VERTEX 01011010 0000018AE420C6D0
Tolerance : 1e-07
- Point 3D : 6.12323399573677e-17, -1.49975978266186e-32, -1
TShape # 8 : EDGE 01010000 0000018AE3049C00
+9 -9
Tolerance : 1e-07
same parametrisation of curves
same range on curves
degenerated
- PCurve : 1 on surface 1, range : 0 6.28318530717959
UV Points : 0, 1.5707963267949 6.28318530717959, 1.5707963267949
TShape # 9 : VERTEX 01011010 0000018AE420C600
Tolerance : 1e-07
- Point 3D : 6.12323399573677e-17, -1.49975978266186e-32, 1
-------
Dump of 4 Curve2ds
-------
1 : Line
Origin :0, 1.5707963267949
Axis :1, 0
2 : Line
Origin :6.28318530717959, -6.28318530717959
Axis :0, 1
3 : Line
Origin :0, -6.28318530717959
Axis :0, 1
4 : Line
Origin :0, -1.5707963267949
Axis :1, 0
-------
Dump of 1 Curves
-------
1 : Circle
Center :0, 0, 0
Axis :-2.44929359829471e-16, -1, 0
XAxis :1, -2.44929359829471e-16, 0
YAxis :0, 0, 1
Radius :1
-------
Dump of 0 Polygon3Ds
-------
-------
Dump of 0 PolygonOnTriangulations
-------
-------
Dump of 1 surfaces
-------
1 : SphericalSurface
Center :0, 0, 0
Axis :0, 0, 1
XAxis :1, 0, -0
YAxis :-0, 1, 0
Radius :1
-------
Dump of 0 Triangulations
-------
-------
Dump of 0 Locations
-------
可见，球面的数据中有3条边
2、C++遍历球面的边
下面通过C++来读取所有边的参数范围，并判断边是否退化为点。
// OpenCascade library.
#define WNT
#include
#include
#include
#include
#include
#include
#pragma comment(lib, "TKernel.lib")
#pragma comment(lib, "TKMath.lib")
#pragma comment(lib, "TKBRep.lib")
#pragma comment(lib, "TKTopAlgo.lib")
#pragma comment(lib, "TKPrim.lib")
/**
* @breif Find the face for the given edge, i.e the face which the given edge is on it.
*/
TopoDS_Face FindFaceOfEdge(const TopoDS_Shape& theShape, const TopoDS_Edge& theEdge)
{
TopoDS_Face theFace;
TopTools_IndexedDataMapOfShapeListOfShape theMap;
TopExp::MapShapesAndAncestors(theShape, TopAbs_EDGE, TopAbs_FACE, theMap);
const TopTools_ListOfShape& theFaces = theMap.FindFromKey(theEdge);
TopTools_ListIteratorOfListOfShape theIterator(theFaces);
for (theIterator.Initialize(theFaces); theIterator.More(); theIterator.Next())
{
theFace = TopoDS::Face(theIterator.Value());
}
return theFace;
}
void TestSingularity(void)
{
TopoDS_Shape theSphere = BRepPrimAPI_MakeSphere(1.0);
for (TopExp_Explorer edgeExp(theSphere, TopAbs_EDGE); edgeExp.More(); edgeExp.Next())
{
const TopoDS_Edge anEdge = TopoDS::Edge(edgeExp.Current());
Standard_Real aFirst = 0.0;
Standard_Real aLast = 0.0;
gp_Pnt2d U1V1;
gp_Pnt2d U2V2;
Standard_Boolean IsDegenerated = BRep_Tool::Degenerated(anEdge);
BRep_Tool::Range(anEdge, aFirst, aLast);
BRep_Tool::UVPoints(anEdge, FindFaceOfEdge(theSphere, anEdge), U1V1, U2V2);
std::cout << "Edge is Degenerated: " << (IsDegenerated ? "True" : "False") << std::endl;
std::cout << "Edge parameters on face: " << std::endl;
std::cout << " (" << U1V1.X() << ", " << U1V1.Y() << ")" << std::endl;
std::cout << " (" << U2V2.X() << ", " << U2V2.Y() << ")" << std::endl;
std::cout << std::endl;
}
}
int main(int argc, char* argv[])
{
TestSingularity();
return 0;
} Edge is Degenerated: True
Edge parameters on face:
(0, 1.5708)
(6.28319, 1.5708)
Edge is Degenerated: False
Edge parameters on face:
(6.28319, -1.5708)
(6.28319, 1.5708)
Edge is Degenerated: True
Edge parameters on face:
(0, -1.5708)
(6.28319, -1.5708)
Edge is Degenerated: False
Edge parameters on face:
(0, -1.5708)
(0, 1.5708)
