CharacterBody3D move_and_slide() freezes the game when colliding with Concave Collision Polygons or ConvexHulls

[alfredbaudisch]

Godot version

4.0-beta9 and 4.0-master-branch

System information

Windows 10, Ryzen 9 5900X, GTX 3080Ti

Issue description

When moving a CharacterBody3D using move_and_slide() and colliding against a Concave Collision Polygons or ConvexHulls with >100 vertices, processing freezes from many ms to sometimes seconds:

https://user-images.githubusercontent.com/248383/209200310-13cd77c4-fa4b-4530-8c4f-7626791e3dd1.mp4

Similar issues

This may be a duplicate of other similar issues like https://github.com/godotengine/godot/issues/50300, but my case was requested by @reduz via Twitter.

Steps to reproduce

• Import a mesh with >100 vertices
• Generate Trimesh Static Body collision
• Implement any barebones character controller with CharacterBody3D, a Capsule collider and move with move_and_slide()
• Move and collide against the mesh, everything freezes

Minimal reproduction project

GodotFreezingCharacter3D.zip

This test project has 4 character controller implementations (2x 1st Person and 2x 3rd Person ones), to show that it happens regardless of the controller complexity or simplicity:

To test, simply move forward (WASD + mouse) and collide against the barrels, then move around colliding with the barrels and also collide with the walls, to see the difference (like my example video above).

[rburing]

As far as I can tell the problem with convex collision is different from the problem with trimesh collision.

Collision with the trimesh collision shapes causes lag spikes (FPS drop) because there are 1444 triangles in each barrel.

To change the collision shapes to convex: in the advanced importer for the FBX file, change Physics Shape Type to Simple Convex, press Reimport, and restart the editor (for some reason reimport seems bugged currently).

Collision with the convex collision shapes does not cause lag spikes (FPS remains stable) but you get stuck/caught on them instead of sliding along them, almost certainly because of the almost coplanar adjacent faces, see https://github.com/godotengine/godot/issues/65596#issuecomment-1242948809.

[reduz]

I did some research here and it appears that the problem here regarding what kills performance is that the way we do the sweep test here is pretty inefficient, this should be redone to use a proper GJK based sweep test.

[Saul2022]

Seems like it persists on the beta 14.

[jitspoe]

I've noticed that, even with pretty simple geometry, the framerate completely tanks on development builds when using move_and_slide(), especially when a character moves into a corner where, I assume, multiple contacts are generated. move_and_collide() isn't quite as bad, but still results in sub-60 FPS. Hoping this pending change will improve it!

[alfredbaudisch]

the framerate completely tanks on development builds when using move_and_slide(), especially when a character moves into a corner where,

I know the issue is still open, which is a confirmation that the issue is still present. But just to make sure, I re-tested, and I want to confirm that this is still the case with 4.0-stable. Also, my MRP from the issue still performs as badly as originally (i.e. the issue still persists as reported).

[jitspoe]

I just had another issue that I think is related. I recently set up my spawners so they could be placed directly on the ground and I would read in the height of the capsule of the player and enemies to offset them and place them exactly on the ground. After I did that, I the game ran at like 10-15 FPS for a few seconds then acted normally. On subsequent runs, it didn't do that, but every once in a while it has that behavior. Framerate is completely unplayable for a few seconds then it settles down.

Unfortunately, it reproduces rarely, and this is on a larger project, so I can't come up with a consistent minimal repro case. Also, the profiler doesn't indicate where the performance hit comes from. It was all under "Process time", not on any of the script functions or physics. Perhaps something needs to be added to the proper profiler category to help track this down for certain.

[TechnoLukas]

I do have similar issue on Godot 4.2.1. I don't use move_and_slide, I use move_toward and lean in the direction. Also added particles to visually see the "lag"

STEPS:

• Use my character controller
• add 2 torus close to each other
• Go to the gap between them

This is my demo project: https://github.com/TechnoLukas/Godot4-Basic3dStarter/tree/simplified

[alfredbaudisch]

@TechnoLukas while not a solution to Godot's physics, I recommend that you use Godot Jolt. I have long abandoned the usage of Godot Physics in favor of Jolt and these issues are not present.

[TechnoLukas]

@alfredbaudisch Thank you! Yes, Godot Jolt solved this issue, and made physics more smooth. 👍

[maridany1999]

I'm using Version 4.3.dev6.mono, this issues still exists. I'm using a CapsuleShape3D as the collision shape for the player and MoveAndSlide to move the player. Additionally, the collision the player is colliding agaisnt is round shape but with only 50 vertices.

Also, I've come to notice that everytime there's low fps spikes, colliding agaisnt specific collisions and at certain angles, the value of active objects and islands lower to 1, which is when the fps decrease a lot.

The image below also shows the profiler, more specific the Physics 3D section. When the FPS drop drastically, at the exact moment that the active objects also lowers from 2 to 1, it also creates an loop of items repeating itself: