Johan Jansson wrote: > Anders Logg wrote: > >> Yes, the mesh ordering used in DOLFIN (intentionally) screws up any >> ordering, like all cells being "right-oriented" or similar. >> >> If this is a problem for GTS, we need to do something about the GTS >> interface (not the mesh). >> >> >> > > I'm pretty sure this is not a problem for GTS. The GTS algorithm > (gts_bb_tree_overlap()) is an axis-aligned bounding-box tree algorithm. > It only operates on bounding boxes of cells, so the orientation is > irrelevant. This is also why the algorithm can be used for tetrahedral > meshes, even though GTS supposedly is only for triangulated surfaces. > > Johan > Continuing..
This view was a bit too simplistic. After the bounding box has been found, we do actually need to perform a cell intersection test. The orientation does play a factor in TriangleCell::intersects() and TetrahedronCell::intersects() (which are implemented using the GTS/Shewchuk predicates actually..). However, a local reordering (using orientation()) is implemented for triangles, but it seems to be missing for tetrahedra (should be easy to add though). Since Kristen has a tetrahedral mesh I guess this is the likely candidate for error.. Johan _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
