Hey thaks! I’ll use the BoundingBox for sure in the future!
Now luckly all my mesh was in the Z=0 plane, so yesterday night I resolved with this trick: http://img6.imageshack.us/img6/7830/vvvvlr.jpg
I still had the vectors spread, so I just multiply the diagonal of each mesh for the 1.0700 factor.
Perhaps this works well only for square-shaped mesh…
BTW, how can I avoid the distorsion when I apply a texture on a mesh not really square-shaped? http://img204.imageshack.us/img204/333/photomd.jpg
The only solution I can think is to divide the mesh in lots of sub-mesh and distribuite the texture on them…
:/