tpaviot/oce — Issue #143: Over refined B-spline mesh
Author: jeromerobert
Created: 2011-10-24 15:26:59+00:00
State: open

Here are a geometry and a program that show the B-spline mesher is still buggy in OCCT 6.5.1. The BRep is a sphere trimmed by a square made of 120 TopoDS_Edge. The program is run with the B-spline mesher and without (thanks to the attached patch). In both cases I give the number of triangles for the sphere as a reference (the optimal mesh), and for the sphere converted to GeomAbs_BSplineSurface.

Without the patch (B-spline mesher):
$ ./a.out
Number of triangles for the sphere geometry: 886
Number of triangles for the nurbs geometry: 46948

With the patch (generic mesher):
$ ./a.out
Number of triangles for the sphere geometry: 886
Number of triangles for the nurbs geometry: 1676

This geometry is not a pathological case as over refined trimming are more than common in real world. I think a mesh 28 time too refined should be considered as a bug.

See the patch, source code, geometry and OCC bug at http://www.opencascade.org/org/forum/thread_22070/

Would it be possible to include the patch in OCE until it's fixed in OCCT ?