Rigidbody is stuck when placeable has a parent ref

[tapanij]

Tried to move a child entity by adding linear velocity. Will stay in one point unless I remove the parent ref.

Example scene: https://dl.dropboxusercontent.com/u/60485425/Playsign/parentBug.txml

[jonnenauha]

I would assume this is how it should work? Once parented the child is just along for the ride and physics impulses etc. should be applied to the parent?

[cadaver]

Bullet always operates in world space, so when a rigid body is parented and it moves, the transform needs to be changed back into the parent's space. Support for this has been implemented but apparently it has broken, or has never worked properly for moving rigidbodies.

[cadaver]

In general, a parented rigidbody should be avoided, because a rigidbody is supposed to represent a free-standing object in the world, and when the parent is moved, the rigidbody will move also (non-physically). The extra coordinate space transformations will also cost performance.