After some investigation why the .obj files I created in Rhino wont load in vvvv, I noticed that it appears that Mesh(DX11.GeometryAssimp) cant seem to handle OBJ files without texture coordinate indices, even though they are optional.
According to this Wikipedia article on the OBJ Format:
As texture coordinates are optional, one can define geometry without them, but one must put two slashes after the vertex index before putting the normal index.
The format for the indexes then becomes:
"f v1//vn1 v2//vn2 v3//vn3 ... "
Whereas if vt is specified it would be:
"f v1/vt1/vn1 v2/vt2/vn2 v3/vt3/vn3 ..."
Both .obj files open correctly in any other software.
Attached is a small patch that shows whats happening and the difference in the code.
obj_indices.zip (5.7 KB)