# How to simulate a "small" rigid sphere that collides with an elastic surface?

This topic is 2836 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Hi
I'm about to model a tennis net for a sports game. As the first iteration I was thinking of simulate the movement of the net with cloth simulation and Verlet integration. When the ball touches the net the vertices will be pushed to the outer edge of the ball accordingly. So I think I got the animation of the net sorted.

But I'm not entirely sure how to simulate the interaction between the ball and the net. The ball must bounce against the net. Maybe I can model the net as a rubber membrane? What I'm looking for is a method to simulate a "small" rigid sphere that collides with an elastic surface. Does anybody know of some method I can use?

Thanks

##### Share on other sites
Well, if you can animate the net as you say, then you could simply calculate a spring force from the offsets of the net's vertices.
Simply SprinfForceFromVertice = VerticeOffset*STIFFNESS; Or something like that. Maybe you could fake it just by the distance between the original position, and the altered position. Then sum up all the forces from the deforming vertices and apply it to the ball.
You can do it accurately, or just do something that looks good.

##### Share on other sites

Well, if you can animate the net as you say, then you could simply calculate a spring force from the offsets of the net's vertices.
Simply SprinfForceFromVertice = VerticeOffset*STIFFNESS; Or something like that. Maybe you could fake it just by the distance between the original position, and the altered position. Then sum up all the forces from the deforming vertices and apply it to the ball.
You can do it accurately, or just do something that looks good.

I was thinking along the same lines you suggest before. There would be problem if other forces than the ball worked on the net however, such as weather and gravity; and there would also be inaccuracies if the ball clipped the net and still moved when ball-net interacted for the second time. Also in the method I'm using only the external forces are known explicitly. The internal forces are modelled implicitly as springs between the vertices and computed as offset of the vertex position. Further the movement of the mesh is propagated between neighbours over many frames. Therefore my plan was to simulate the ball movement as "a sphere colliding with an elastic surface" and feed the Verlet integration with the balls position.

I fully agrees that a simple system that looks good is something beneficial :-)

##### Share on other sites
"There would be problem if other forces than the ball worked on the net however, such as weather and gravity; and there would also be"

"I fully agrees that a simple system that looks good is something beneficial :-)"

Is the net the most important feature in your application? I guess not... So weather? gravity? Well, you know what you are doing.....

1. 1
2. 2
Rutin
16
3. 3
4. 4
5. 5

• 26
• 11
• 9
• 9
• 11
• ### Forum Statistics

• Total Topics
633704
• Total Posts
3013460
×