Erratic Vehicle Physics

[MrMinimal]

Pre collision / free falling:

Godot version

4.0.alpha.5

System information

Ubuntu 21.04

Issue description

Observed behaviour A VehicleBody3D with multiple VehicleWheel3Ds flys off the second a collider is hit.

Expected behaviour The vehicle would come to rest, with the suspension dampening the fall after a couple of seocnds.

Post collision / just before flying off into the distance:

Steps to reproduce

1. Open the reproduction project
2. Start the reproduction project
3. Observe free fall
4. Observe vehicle very much not coming to rest

The example project contains a basic VehicleBody3D vehicle with 6 wheels added. Only wheel radii were adjusted and moved to the meshes correct posion.

Minimal reproduction project

godot-vehicle-demo.zip

[ThomasT75]

I had the same problem it was fixed by resetting all of the transforms, and moving only the wheels into place. The cause was a collision shape with non-zero transform, but I didn't move that collision shape it inherited his transform from the mesh I used to create the collision shape, so now that brings me to the point. Your chassis (aka VehicleBody3D) doesn't have a collision shape which is needed, but the editor doesn't give a warning :) This is how I did, and it works: (The script is only there to change steering, and engine_force with WASD) Btw you might want to change the wheels suspension stiffness :D