I have a parent object with two children, the parent has a box collider and a non-kinematic rigidbody, the children have sphere colliders and no RBs. The two children do not generate collisions when they hit a static non-convex mesh collider with no RB (the ground). It looks like from the collision matrix, this should work. Do the children need to have RBs attached? They can’t have non-kinematic RBs, since they need to move with the parent, and kinematic RBs do not generate collisions. I thought only the parent needed a RB in order for child colliders to collide with things. How do I get the child colliders to collide with my static mesh collider?
Children shouldn’t have rigidbodies, no. Unity - Manual: Introduction to collision
I did a quick test with the setup you described, and the collision works as expected:
–Eric
Children can have rigidbodies. I use child rigidbodies often for composing complex multi-body machines that fit in a single prefab. Check out my replies in this post:
The article from Unity manual can be misunderstood as “children shouldn’t have rigidbodies”. It really refers to the compound colliders: a set of colliders are considered part of a single rigidbody. In this case the children colliders shouldn’t have rigidbodies. If they had, children would just behave as independent bodies regardless of the parenthood relationship, which in most cases is not what users expect.
Yes, I was talking about in the context of compound colliders, which this topics seems to be about.
–Eric