Strange sphere/physics rolling behaviour when scaled

I have a sphere (imported model) rolling along a flat surface. It’s controlled by the arrow keys via AddForce(). It works very well, and the physics engine and friction take care of it rolling (rather than sliding) realistically. I can import the ball at any size and it works consistently, however if I manually scale the ball’s transform instead, by half (.5,.5,.5), or less, it moves very jerkily. I’ve tried adjusting the friction settings, in case the engine uses scale for it’s friction calculation, but to no avail.

At various points in the game I need this ball to be continuously scaleable. Is there another way to approach this problem?


What kind of Collider are you using for your imported sphere model?
If it’s a MeshCollider, make sure to check ‘convex’ and ‘smooth sphere collisions’ in the component properties.
I also don’t recommend you to use MeshColliders if the base mesh very high poly, as you will run into performance issues quickly.

As an alternative I suggest to attach the built-in sphere collider. That should be insensitive to scale.

hope that helps - looking forward to the next Katamari Damacy :wink: