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Votes

0

Found in

2018.4

2019.4

2020.3

2020.3.8f1

2021.1

2021.2

Issue ID

1337722

Regression

No

Relative Torque does not apply relative to the Rigidbody's axis when the Box Collider is a child of the RigidBody

Physics

-

Reproduction steps:
1. Open project "case_1337722"
2. Open Scene "SampleScene"
3. Enter Play Mode
4. In the Hierarchy tab select GameObject "GameObject (1)"
5. Observe Scene view

Expected result: Object with RigidBody Component rotates around the Y-Axis
Actual result: Object with RigidBody Component doesn't rotate around the Y-Axis

Reproducible with: 2018.4.35f1, 2019.4.27f1, 2020.3.10f1, 2021.1.9f1, 2021.2.0a17

  1. Resolution Note:

    The AddRelativeTorque function takes into account the rotation of the Rigidbody/ArticulationBody and doesn't have to do to anything with this issue. AddTorque produces the same results in cases where the Rigidbody is not rotated, only the child Collider is.

    The reason why the torque gets applied along multiple axes is the Inertia Tensor. When PhysX multiplies the torque that has been provided with the global inverse inertia tensor matrix, the resulting angular acceleration has non-zero components around multiples axes. This can also be seen by using ForceModes that don't take Inertia Tensor into account like ForceMode.Acceleration or ForceMode.VelocityChange.

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