Rigidbody sphere never stops rolling

Unity Engine
1

I have set up a simple scene with a flat cube (ground) and a sphere (ball) to play around and try to simulate a football (soccer) ball physics. However, the ball never stops rolling on the ground. It keeps rolling extremely slow forever, how come?

I’ve tried changing friction values without success. What do I need to do for the ball to behave like it is rolling on grass (stopping full and goes in to sleep)? I’ve changed friction values on the physics materials on both object but I can never get it to fully stop.

What did I miss?

2

You should set a higher sleepAngularVelocity value so once your rigidbody’s angular velocity goes below that value, it will go to sleep.

3

Trying it without success. Shouldn’t the ball keep going slower and slower because of the friction? it doesn’t slow down, it’s keeping a constant low speed after initial slowing down. That constant angular velocity ranges between like 1.5 and down. If I put in another cube as a wall it stops and goes to sleep.

Don’t understand why the friction doesn’t keeps making it roll slower, down to basically standing still.

Edit: I had the “drag” on 0… seems to work properly now.

1 Like
4

Friction won’t slow it down because a sphere only has a tiny point actually touching a cube, so there’s nothing really for friction to act on. It’s not like a real soccer ball where you actually have lots of grass blades and stuff in contact with the ball at various points. Friction works for things like boxes because the entire surface is likely to be in contact with the ground.

–Eric

1 Like
5

You may want to consider angular drag (or even regular drag).

Then base that drag on whatever the ball is hitting.

2 Likes
6

hi,

thanks a lot the drag worked perfectly

…

7

could do something like:

float velocitySqrMagThreshold = 0.6f;
float rBVelocitySqrMag = rigidbody.velocity.sqrMagnitude;

if (rBVelocitySqrMag < velocitySqrMagThreshold)
{
canActivateDragDamping = true;
}
else
{
canActivateDragDamping = false;
}

if (canActivateDragDamping)
{
rigibody.drag = 10;
rigidbody.angularDrag = 10;
}
else if (!canActivateDragDamping)
{
rigidbody.drag = 0;
rigidbody.angularDrag = 0.05f;
}

Note: velocitySqrMagThreshold — I suggest setting this to 0.6 for the sphere issue. Also I suggest setting up lerps instead of what I have here for when drag is kicked into play. It smooths it out so it doesn’t pop. But this should get you started and you can do the lerp code yourself. I donnwanna.

Hope this helps.

8

maybe your “ground” is just a bit rotated? on the X or Z axis?

9

@SpaceManDan @Karsten you guys realize that this thread is created back in 2010 right?

10

oh yeah, necro much. there was something wrong with the database of this forum i seen, there was some threads with extreme high views , maybe they try around again with the new forum software xD

11

I tried to find a solution for many hours, so if it can help : try changing the ground’s collider. It worked for me because I was using a mesh collider instead of a box collider.

12

Thought I’d chime in and say that adjusting the drag worked for me (flat ground, capsule collider on a shell casing object, set drag on 10)
Without drag on 10 it would roll and roll and roll…