When importing a mesh, allow the user to simplify the created physics TriMesh with mesh optimizer.

[basicer]

Adds a new simplification option to the model importer when the trimesh physics mesh mode is selected similar to how the options for convex decomposition are presented.

Also adds GDScript exports to generate a convex shapes and trimesh shapes (both simplified and simplified) to ImportMesh match Mesh.

Closes godotengine/godot-proposals#3603, tested with the example project posted there.

[basicer]

This is my first patch for godot!

I considered also implementing the simplification method on Mesh, but was a bit thrown off by how much code is duplicated between Mesh and ImporterMesh.

[basicer]

[Calinou]

Tested locally, it works as expected. The default parameters seem to generate a collision shape close to the original, but with fewer vertices.

[JoNax97]

I think some of the options can be streamlined. For collision shapes, do we really care about topology? That is to say, do we need to have the 'sloppy' toggle?

[clayjohn]

I think some of the options can be streamlined. For collision shapes, do we really care about topology? That is to say, do we need to have the 'sloppy' toggle?

I agree. These options should be as simple as possible. Ideally just a slider for simplification amount.

[basicer]

I thought about a few options to cut down on the number of tweakable but nothing really came out of it. Sometimes the mesh you get from sloppy is closer to the "idea" mesh, sometimes the non-sloppy one is better, it seems to just depend on the model.

As far as trying to combine the target number or vertices and the target error into a single slider, I'm not sure how what sort of formula you would use to translate simplification amount into those two values.

[fire]

As far as trying to combine the target number or vertices and the target error into a single slider, I'm not sure how what sort of formula you would use to translate simplification amount into those two values.

Godot uses the error metric to distance in autolod. Maybe there's something there you can remix.

[basicer]

I scrapped the slider as it was too laggy with doing the simplification calculation and simplified the whole thing down two three simplification levels. This option only appears when the shape type is Trimesh.

[Calinou]

Tested locally (rebased on top of master 4a01602), it mostly works as expected.

The single setting with 3 options makes the configuration much easier now.

However, the 3D preview doesn't always update after you change the simplification setting in the Advanced Import Settings dialog. It only seems to be consistently updated when you change the physics type from something else to Trimesh.

Testing project: test_collision_shape_simplify_on_import.zip

Off	Low (Conservative)

Medium (Balanced)	High (Aggressive)

[basicer]

However, the 3D preview doesn't always update after you change the simplification setting in the Advanced Import Settings dialog. It only seems to be consistently updated when you change the physics type from something else to Trimesh.

I rebased this on top of 11d3768 and couldn't reproduce this problem, however I do vaguely remember having it at some point while developing. Does this trigger consistently for you?

[Calinou]

Does this trigger consistently for you?

No, it's quite random and unpredictable 🙁

[basicer]

Alright @Calinou , finally figured out whats going on here. The bug fixed in #97837 masked what was going on here, but should be fixed now :).