Edges on 3 triangles


Dear all,

I have a geometry where more than 2 surfaces can intersect, so there are edges that belong to more than 2 triangles (in this case, the tags of all the triangles are different).

When I use mmgs, the resulting mesh is not correct on those edges (the left image is the original mesh, the right is the mmgs result).
The files are here:
geom_1_before.mesh (60.3 KB)
geom_1_before.sol (2.3 KB)

Should mmg be able to handle such cases?

Best regards,



Dear Xavier,

Thank you for pointing out this error. I have committed a correction in the master branch of Mmg. Please, let me know if you still have issues.

Best regards,



Thank you very much


One more question. I (try to?) prescribe mesh sizes at the vertices, but when I run mmgs I get this:

Is is possible there is still an issue with the metric imposed on triple edges?
The mesh & sol are here:
geom_before.mesh (748 Bytes)
geom_before.sol (198 Bytes)

Best regards,



Hello Xavier,

You’re totally right, there is still issues along triple edges: as we are able to store only 2 adjacent triangles per edge, some operators of Mmg doesn’t works. It includes:

  • the collapse operator (we are unable to unrefine triple edges);
  • the node insertor used to reach the wanted edge size (we are able to reach the edge size only roughly);

I will look at it to see if something better is possible (but I am not sure).

Best regards.