One Way Collision shapes cause instability when multiple objects are stacked.

[DragonEngineer]

Describe the bug

If you have 2 or rigidbodies (godot icons thing) stacking on top of another, the bottom most rigidbody will clip into the staticbody (magenta thing)

To Reproduce

Steps to reproduce the behavior:

1. Put many "Box" object on top of the "Belt" object
2. Run the game

Expected behavior The bottom most rigidbody should rest right on top of the magenta block, not partially sunk into the magenta block

Environment:

• OS: Windows 10
• Version 0.7.18
• Godot Version 4.2.1
• Type SIMD Single 2D
• CPU: AMD Ryzen 7 4800H with Radeon Graphics
• GPU: Nvidia Geforce GTX 1650

Files Factory Boxes.zip

• After downloading, need to put the Rapier (SIMD Single 2D) addons inside the addons folder before opening the project
• You can run "test_level.tscn" to see the bug

[Ughuuu]

Seems that if you disable one_way_collision on the shape, everything works. Possibly the problem is in the modify_contacts of the one_way_collision logic.

[Ughuuu]

One way collision will get fixed soon by open PR, next thing to look into at this issue is move_and_slide call getting call, that might cause some instability too.

[Ughuuu]

Fixed in 0.8.1. It was indeed caused by one way direction that has been reworked to be more stable.

https://github.com/user-attachments/assets/b45617c5-776c-4c1c-8927-230378b6e295

I do acknowledge that it does pass a bit into the object. Probably that can be another issue.