Fix quad and n-gon OBJ/faces - Fan-triangulate - #12
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OBJ exports without a Triangulate step contain faces with more than 3 vertices. The manual OBJ parser stored them as-is, so building the numpy face array later failed with an inhomogeneous shape error since it expected every face to have the same length.
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What this fixes
Loading an OBJ file exported without a "Triangulate" step (containing quads or n-gons instead of only triangles) crashed with "Unexpected error loading file: setting an array element with a sequence. The requested array has an inhomogeneous shape..."
Root cause
_parse_obj_groups() stored each face's vertex indices as-is, regardless of how many vertices the face had. _load_obj_with_real_groups() then called np.array(all_faces) on that list, which requires every face to have the same length. A single quad or n-gon mixed in with triangles breaks that assumption.
Fix
Fan-triangulate any face with more than 3 vertices at parse time, so mixed-topology OBJ files load without requiring the user to
pre-triangulate in their 3D software first.
Fixes #9.
Testing
Uploaded a synthetic quad-only OBJ cube (6 quads, 8 vertices, no triangles) through the running app. It now loads correctly as 12
triangles with no error.
Note:
Checked the other import paths (.dae, .stl, .gltf/.glb, .kn5).
Only .obj can actually hit this, the rest triangulate on their own before reaching this code.