Take box as an example
BRepPrimAPI_MakeBox mkBox(10, 10, 10);
TopoDS_Shape aShape = mkBox.Shape();
TopoDS_Shape data structure
See: OpenCascade notes: [OpenCascade topology object: three elements of TopoDS_Shape]
TopoDS_Shape的HashCode
The following two members serve as the main elements for generating hashCode
- Handle(TopoDS_TShape) myTShape;
- TopLoc_Location myLocation;
The direction member TopAbs_Orientation myOrient; does not participate in the generation of HashCode.
Visit vertices
The first traversal method gets the number of TopoDS_Face, TopoDS_Edge, and TopoDS_Vertex built by the body; the
second traversal method gets the number of BRep_TFace, BRep_TEdge, and BRep_TVertex built by the body (the final display form is still TopoDS_Face, TopoDS_Edge, TopoDS_Vertex) . For example: Taking BOX as an example, TopExp_Explorer traverses 48 vertices, 24 edges, and 6 faces; TopExp traverses 8 vertices, 12 edges, and 6 faces.
//第一种遍历方式拿到的是体构建的TopoDS_Face、TopoDS_Edge、TopoDS_Vertex的数量；
//第二种遍历方式拿到的是体构建的BRep_TFace、BRep_TEdge、BRep_TVertex的数量（最终展现形式还是TopoDS_Face、TopoDS_Edge、TopoDS_Vertex）。
//举个例子：以BOX为例
//TopExp_Explorer 遍历出48个顶点、24条边、6片面；
//TopExp遍历出8个顶点、12条边、6片面；
//第一种遍历方式
TopExp_Explorer aExp;
int i = 1;
for (aExp.Init(aShape, TopAbs_VERTEX); aExp.More(); aExp.Next(), ++i )
{
const TopoDS_Vertex& aVertex = TopoDS::Vertex(aExp.Current());
gp_Pnt aPnt = BRep_Tool::Pnt(aVertex);
std::cout << "vertex " << i << ": (" << aPnt.X() << ", " << aPnt.Y()
<< ", " << aPnt.Z() << "), vertex's hash code is "
<< aVertex.HashCode(INT_MAX) << std::endl;
}
//第二种遍历方式
TopTools_IndexedMapOfShape aVertexMap;
TopExp::MapShapes(aShape, TopAbs_VERTEX, aVertexMap);
cout << "vertex count is " << aVertexMap.Extent() << std::endl;
for (int i = 1; i <= aVertexMap.Extent(); ++i)
{
const TopoDS_Vertex& aVertex = TopoDS::Vertex(aVertexMap(i));
gp_Pnt aPnt = BRep_Tool::Pnt(aVertex);
std::cout << "vertex " << i << ": (" << aPnt.X() << ", " << aPnt.Y()
<< ", " << aPnt.Z() << "), vertex's hash code is "
<< aVertex.HashCode(INT_MAX) << std::endl;
}
access edge
//第一种遍历方式拿到的是体构建的TopoDS_Face、TopoDS_Edge、TopoDS_Vertex的数量；
//第二种遍历方式拿到的是体构建的BRep_TFace、BRep_TEdge、BRep_TVertex的数量（最终展现形式还是TopoDS_Face、TopoDS_Edge、TopoDS_Vertex）。
//举个例子：以BOX为例
//TopExp_Explorer 遍历出48个顶点、24条边、6片面；
//TopExp遍历出8个顶点、12条边、6片面；
//第一种遍历方式
TopExp_Explorer aExp;
int i = 1;
for (aExp.Init(aShape, TopAbs_EDGE); aExp.More(); aExp.Next(), ++i )
{
const TopoDS_Edge& aEdge = TopoDS::Edge(aExp.Current());
const TopoDS_Vertex& aFirstVertex = TopExp::FirstVertex(aEdge);
const TopoDS_Vertex& aLastVertex = TopExp::LastVertex(aEdge);
}
//第二种遍历方式
TopTools_IndexedMapOfShape aEdgeMap;
TopExp::MapShapes(aShape, TopAbs_EDGE, aEdgeMap);
cout << "edge count is " << aEdgeMap.Extent() << std::endl;
for (int i = 1; i <= aEdgeMap.Extent(); ++i)
{
const TopoDS_Edge& aEdge = TopoDS::Edge(aEdgeMap(i));
const TopoDS_Vertex& aFirstVertex = TopExp::FirstVertex(aEdge);
const TopoDS_Vertex& aLastVertex = TopExp::LastVertex(aEdge);
Standard_Real fBegin = 0, fEnd = 0;
Handle(Geom_Curve) hCurve = BRep_Tool::Curve(aEdge, fBegin, fEnd);
if (!hCurve.IsNull())
{
//边是条几何线，如直线、椭圆线、贝塞尔曲线等等
//散列化，进行取点
float fLen = float(fEnd - fBegin);
int ulNbOfPoints = 30;
for (int i = 0; i < ulNbOfPoints; i++)
{
const gp_Pnt& ptPoint = hCurve->Value(fBegin + (fLen * float(i)) / float(ulNbOfPoints - 1));
}
continue;
}
TopLoc_Location locPolygon;
Handle(Poly_Polygon3D) hPolygon3D = BRep_Tool::Polygon3D(aEdge, locPolygon);
if (!hPolygon3D.IsNull())
{
//边是条多段线（曲线的近似表示）
Standard_Integer nNodeCount = hPolygon3D->NbNodes();
const TColgp_Array1OfPnt& mNodes = hPolygon3D->Nodes();
for (int i = 1; i <= nNodeCount; ++i)
{
const gp_Pnt& ptPoint = mNodes(i);
}
}
}
Attached is the class hierarchy of geometric curves in occ
face-to-face visit
//拆分三角形
Bnd_Box bounds;
BRepBndLib::Add(aShape, bounds);
bounds.SetGap(0.0);
Standard_Real xMin, yMin, zMin, xMax, yMax, zMax;
bounds.Get(xMin, yMin, zMin, xMax, yMax, zMax);
Standard_Real deflection = ((xMax - xMin) + (yMax - yMin) + (zMax - zMin)) / 300.0 *0.5;
BRepMesh_IncrementalMesh(aShape, deflection, false);
//第一种遍历方式拿到的是体构建的TopoDS_Face、TopoDS_Edge、TopoDS_Vertex的数量；
//第二种遍历方式拿到的是体构建的BRep_TFace、BRep_TEdge、BRep_TVertex的数量（最终展现形式还是TopoDS_Face、TopoDS_Edge、TopoDS_Vertex）。
//举个例子：以BOX为例
//TopExp_Explorer 遍历出48个顶点、24条边、6片面；
//TopExp遍历出8个顶点、12条边、6片面；
//第一种遍历方式
TopExp_Explorer aExp;
int i = 1;
for (aExp.Init(aShape, TopAbs_FACE); aExp.More(); aExp.Next(), ++i )
{
const TopoDS_Edge& aEdge = TopoDS::Edge(aExp.Current());
const TopoDS_Vertex& aFirstVertex = TopExp::FirstVertex(aEdge);
const TopoDS_Vertex& aLastVertex = TopExp::LastVertex(aEdge);
}
//第二种遍历方式
TopTools_IndexedMapOfShape aFaceMap;
TopExp::MapShapes(aShape, TopAbs_FACE, aFaceMap);
cout << "face count is " << aFaceMap.Extent() << std::endl;
for (int i = 1; i <= aFaceMap.Extent(); ++i)
{
const TopoDS_Face& curFace = TopoDS::Face(aFaceMap(i));
BRepAdaptor_Surface adaptorSurface(curFace);
GeomAbs_SurfaceType surfaceType = adaptorSurface.GetType();
//GeomAbs_Plane,
//GeomAbs_Cylinder,
//GeomAbs_Cone,
//GeomAbs_Sphere,
//GeomAbs_Torus,
//GeomAbs_BezierSurface,
//GeomAbs_BSplineSurface,
//GeomAbs_SurfaceOfRevolution,
//GeomAbs_SurfaceOfExtrusion,
//GeomAbs_OffsetSurface,
//GeomAbs_OtherSurface
//前面对面进行了三角化（BRepMesh_IncrementalMesh）
//此处可以取出三角面信息
TopLoc_Location aLoc;
Handle(Poly_Triangulation) mesh = BRep_Tool::Triangulation(
curFace, aLoc);
if (mesh.IsNull())
{
continue;
}
const Poly_Array1OfTriangle& mTriangles = mesh->Triangles();
const TColgp_Array1OfPnt& mNodes = mesh->Nodes();
for (int g = 1; g <= mesh->NbTriangles(); g++)
{
// Get the triangle
Standard_Integer N1, N2, N3;
mTriangles(g).Get(N1, N2, N3);
// change orientation of the triangles
if (curFace.Orientation() != TopAbs_FORWARD) {
Standard_Integer tmp = N1;
N1 = N2;
N2 = tmp;
}
gp_Pnt V1 = mNodes(N1);
gp_Pnt V2 = mNodes(N2);
gp_Pnt V3 = mNodes(N3);
if (!aLoc.IsIdentity())
{
V1.Transform(aLoc.Transformation());
V2.Transform(aLoc.Transformation());
V3.Transform(aLoc.Transformation());
}
}
//.....
}
Attached is the class hierarchy of geometric surfaces in occ
Wire, Shell, Solid access
Similar to above