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Articulation Body colliders intersect without colliding when using non-fixed articulation



How to reproduce:
1. Open the user's attached project
2. Open scene Test Scene
3. Press the Play button and observe the three TestSetup GameObjects

Expected result: all three TestSetup GameObjects show colliding cubes without intersection
Actual result: "TestSetup - NonFixed Articulation" cubes intersect with each other without colliding

Reproducible with: 2020.3.34f1, 2021.3.3f1, 2022.1.1f1, 2022.2.0a14
Could not test with: 2019.4.39f1 (Articulation Body not available)

  1. Resolution Note:

    In the provided project, the cube that "falls through" actually gets forced through the other collider by its own ArticulationDrive settings. (The Damping is set to a large value and Target Velocity is set to 2) This ends up forcing the collider to reach some velocity, overriding the pushback it gets from intersecting the other collider. You can witness this by opening the Physics Debugger on the latest Unity version and entering play mode step by step. When the bodies intersect you can see the pushback visualized in pink arrow gizmos. If you set Damping to 0, the cubes will collide and the top one will not fall through.

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