Only triangulate n-gons when necessary for calc_tangents #379
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Good catch! Thank you very much for the fix! I agree that it is good enough to fix the triangular meshes for now.
To finally merge this PR, we need to update those reference exports in the repo, so that we can keep using them for future regression tests.
If you have a Blender2.8x environment available, you can rebase to the current master HEAD, do a make update-examples and commit the changes. It's okay if you don't have one, hold on a while and I will come up with a way to simplify the flow. Thanks 🙂
io_scene_godot/converters/utils.py
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| mesh.calc_tangents() | ||
| except RuntimeError: | ||
| # Mesh must have n-gons | ||
| logging.info( |
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You can use logging.warning here, we have a hook to populate warning message to UI.
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I wasn't sure if I should use a warning since it's much more visible. I updated it and also tweaked the message slightly for more friendliness, see if it's okay.
This shouldn't change anything atm since the mesh is triangulated beforehand, but this will allow us a non-triangulated mesh in the future, which avoids problems where the mesh triangulation is wrong; loop_triangles is always the "true" triangulation.
No longer need to ask the mesh converter to triangulate.
This means it is no longer required to ask for triangulation if asking for tangents.
It is now as if it were always False. Triangulation will only occur if needed for calc_tangents. This was only True in mesh.py. Now that it is False there, triangulate_mesh will be skipped for any meshes without (>4)-gons, which solves issues of bad triangulation/damaged normals for these meshes.
This should confine damage caused by triangulation to n-gons only.
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Neat. I rebased and ran |
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Thanks! |
Hi.
There is a problem with triangulate_mesh; it can calculate the wrong triangulation, and it can damage normals. But triangulating is necessary to calculate tangents if there are (>4)-gons in a mesh. The goal of this PR is to limit the damage caused to only (>4)-gons. In particular, meshes with only tris/quads should now be fixed.
(I am not aware of a fix that works for everything; for reference, the FBX and glTF exporters instead opt to omit tangents when there are (>4)-gons.)
What I changed:
Fixes #319 (or at least the collar); this one had its normals damaged.
Fixes #361; this one had the wrong triangulation.
Example: a Cylinder with rotated normals.