[Gmsh] Combine different meshes in same geometry

[Marco Cargnelutti]

Dear gmsh users,

I'm using gmsh to create a 2d geometry that will be meshed partly with
quadrangles (let's say an external square with an hole) and partly
with triangles (the internal hole).

The triangular mesh is made with another mesh generator so I merge the
related .msh file in the .geo file with

Merge "triangular_part.msh";

then I make the part with quadrangles with "Mesh->2d" in GUI.

The first problem is that when the quadrangles mesh is created there's
a mismatch between the border points of the internal hole (already
mesh) i.e. the internal hole already meshed is not taken account of
when the quadrangles mesh is created.

The second problem is that I don't find a way to Extrude the merged file in 3d.
It works for the geometry and the quadrangles mesh but fails with the
merged mesh.

If somebody could help me that'll be greatly appreciated :)

Thanks a lot in advance!

Marco