I think OCC can do the job, but it's not obvious. The following discussion might help you: http://www.opencascade.org/org/forum/thread_15411/
Please let us know if you get something working. Thomas 2010/2/25 Willy Hertz <willy.he...@yahoo.com> > Hi Thomas, > I understand the problems with changing topology by moving vertices. > > But there are situations where no such topology changes can happen > (wireframe of edges, triangular faces), and in other situation I would take > care of updating the topology. > > All this depends on the simple question: how can I modify the coordinates > of the vertices of a shape? > > I am discussing with these diagrams in mind : > > http://1.bp.blogspot.com/_ZnQO9nI8DrY/SYn-gThQeZI/AAAAAAAAAGs/C9FUDoDKdkY/s1600-h/abstract-1.png > > http://2.bp.blogspot.com/_ZnQO9nI8DrY/SYn-gi04zCI/AAAAAAAAAG0/ed5c_GHlW5g/s1600-h/abstract-2.png > (It is the last two diagrams on > http://opencascade.blogspot.com/2009/02/topology-and-geometry-in-open-cascade.htmlin > case the picture links are broken) > > Each Compound, Face, Edge has a TopoDS_TShape list of subshapes. Iterating > through them should lead me to the Vertex subshapes. > Modifying their 3D_point should be reflected in the geometry of each > element which is higher in the hierarchy of subshapes. > Is it possible to iterate like this in pythonOCC? In OpenCascade? Is it the > wrong track? > > Thank you > Willy > > > ________________________________ > From: Thomas Paviot <tpav...@gmail.com> > To: pythonOCC users mailing list. <pythonocc-users@gna.org> > Sent: Thu, February 25, 2010 2:37:25 PM > Subject: Re: [Pythonocc-users] retrieve vertices of an edge > > Willy, > > The use of hash codes in the Topology module *is* the essential difference. > > Regarding your sample at the end of the message, the result is not a > surprise: the t.vertices() returns an iterator over the shape topology. When > moving the vertex, you just move a copy of this vertex. But you also have to > tell the TopoDS_Shape that it has to take the new coords into account. In > your sample, when moving the vertex, you actually don't modify the shape, so > the second time you iterate the vertices, you get the same results. > > I remember we already discussed that topic with Jelle: if one move a > vertex, how could we update the underlying topology? This question is not > simple, since when moving one vertex, you may modify the topology: for > instance, if you move one vertex from a cylinder shape, the resulting shape > is not a cylinder anymore. I know it is doable in the SpaceClaim CAD > software: you load any topology (from a STEP file for instance), and then > you just drag edges/vertices while the kernel ensures the shape consistency. > > Jelle started to implement something in this way: the Topology module > provides a edges_from_vertex(self, vertex) method that returns edges > connected to a vertex. But I don't know which algorithm should be performed > over resulting edges. > > Best Regards, > > Thomas > > > > > > > _______________________________________________ > Pythonocc-users mailing list > Pythonocc-users@gna.org > https://mail.gna.org/listinfo/pythonocc-users >
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