uv value lost

there are some files when I export from blender. There are actually UV values that existed in that file. But when I load them from trimesh, the uvs had gone.

please see the file below:

tmp.tmp.obj:

# Blender v2.82 (sub 7) OBJ File: ''
# www.blender.org
mtllib tmp.tmp.mtl
o Cube
v 1.000000 1.000000 -1.000000
v 1.000000 -1.000000 -1.000000
v 1.000000 1.000000 1.000000
v 1.000000 -1.000000 1.000000
v -1.000000 1.000000 -1.000000
v -1.000000 -1.000000 -1.000000
v -1.000000 1.000000 1.000000
v -1.000000 -1.000000 1.000000
vt 0.625000 0.500000
vt 0.875000 0.500000
vt 0.875000 0.750000
vt 0.625000 0.750000
vt 0.375000 0.750000
vt 0.625000 1.000000
vt 0.375000 1.000000
vt 0.375000 0.000000
vt 0.625000 0.000000
vt 0.625000 0.250000
vt 0.375000 0.250000
vt 0.125000 0.500000
vt 0.375000 0.500000
vt 0.125000 0.750000
vn 0.0000 1.0000 0.0000
vn 0.0000 0.0000 1.0000
vn -1.0000 0.0000 0.0000
vn 0.0000 -1.0000 0.0000
vn 1.0000 0.0000 0.0000
vn 0.0000 0.0000 -1.0000
usemtl Material
s off
f 1/1/1 5/2/1 7/3/1 3/4/1
f 4/5/2 3/4/2 7/6/2 8/7/2
f 8/8/3 7/9/3 5/10/3 6/11/3
f 6/12/4 2/13/4 4/5/4 8/14/4
f 2/13/5 1/1/5 3/4/5 4/5/5
f 6/11/6 5/10/6 1/1/6 2/13/6

there are many vt values in the obj file. but if I load it like this:

m = trimesh.load('./tmp.tmp.obj')
print(m.visual.uv)  ---> None

[zachzeyuwang]

@mikedh I just confirmed that mesh.vertices[i] doesn’t necessarily correspond to mesh.visual.uv[i]. In fact, #v and #vt are not always the same, because UV mapping is on a per-face basis, not per-vertex: https://stackoverflow.com/questions/27777349/handling-obj-files-why-is-it-possible-to-have-more-vertextextures-vt-than-ve.

I believe there is a missing feature in trimesh. mesh should have an attribute similar to faces, say faces_vts, that stores the texture coordinates of each vertex on each face.

[mikedh]

Hey, yeah it is converting it from a per-face to per-vertex: https://github.com/mikedh/trimesh/blob/dc8f59e58ca2313e05c5d9216d127c8b9b5bf583/trimesh/visual/texture.py#L216-L309