Sphere won't roll in a straight line...?

Unity Engine
1

Hi,

I’m having some trouble getting a sphere to move in a straight line across a flat surface. I’ve set up a test scene which draws a trajectory, much like a pool game’s aiming aid, and apply an AddForce along the vector, but the ball always ‘curls’ away from the trajectory. The stronger the force, the higher the curl.

I’ve tried endless combinations of material and rigidbody settings - the only way to get the ball to follow the trajectory is to set both the ball and the plane’s materials to 0 angular friction, but this is no use as I want the ball to roll.

More recently I’ve noticed that the velocity sleep and angular sleep settings aren’t working (they’re at default values) - the ball is constantly jittering (the only time force is added is on touch end).

Geometry is scaled correctly, mass is set appropriately and so on.

I raised this in a previous thread (Scripting forum), when I thought the answer may simply be my method of invoking force, but the answer still eludes.
http://forum.unity3d.com/viewtopic.php?t=27031

Any ideas appreciated…

Cheers

2

Maybe the dynamics engine is reading the low poly surface of the sphere which would quickly divert it’s course,
then any small deviation is multiplied by the force.

3

The sphere is using a Sphere Collision component so resolution shouldn’t be an issue…

The deviation appears to be predictable - it’s always relative to the amount of force applied. And it also only occurs in off-axis directions (so pushing along x or z works perfectly, irrespective of the sphere’s orientation).