I’m seeing unexpected collision responses in cases where the default scene root of an actor is simulating physics and is set to collide with the ground. However, it has one or more non-simulating primitives attached and welded to it that are set to ignore collisions with all object types and channels. In many cases, an actor set up this way will unexpected fall through any surface.
In playing around to create the repro example, I’ve found a number of slightly different combinations that work the way I’d expect. The repro seems rather specific, and appears to have something to do with which collision settings end up being used when the bodies are welded together.
Steps to Reproduce
In the provided project, open TestMap and hit play. I have provided five cases in the map, from left-to-right:
- The problematic case
- The same setup, with auto-welding disabled on the child component
- The same setup, with the child also set to simulate physics
- The same setup, with the default scene root using a different object type (this works as expected in the repro, but falls through the world in our actual project)
- The same setup, with the child primitive removed
Hi,
Apologies for the delay, thank you for the detailed repro project. It does sound like a bug as the tool tip says physic settings like collision profile and body settings are determined by the root.
I went ahead and created a bug report for this issue that can be tracked here if/when it’s approved for public visibility: https://issues.unrealengine.com/issue/UE-290782.
There is no ETA as priorities for bugs and features can shift at any time.
Regards