wierd sphere physics

Unity Engine
1

Hi all,

I noticed a thread in another forum where someone was having trouble with a ball moving up a slope when it should have been moving down.

I have a similar problem in that I have a completely flat surface which has a mesh collider component onto which I have placed a sphere with a rigidbody component. When I go to game mode the ball rolls all over the place. I would have expected it to not really roll anywhere.

I have played around with the angular drag parameter as well as others but cant seem to get the ball to behave as expected. Even when I tilt the surface the ball is still not really rolling convincingly.

What am I doing wrong?

2

This is a bug in unity 1.0.4.
We are smoothing normals of the mesh when we shouldn’t.

This affects the collision detection between spheres and meshes.
The bug will be fixed with unity 1.1 beta 1.

Until then you can work around it by tesselating your mesh more.
Tesselate it especially around hard edges.

The problem is that we basically interpolate the normals between all adjacent triangles for sphere - mesh collisions. So if you have a box that is not tesselated it will pull the ball towards the edge.

3

aha thanks - thought I was going mad there for a while :wink: