Keeping bodies from going through other bodies

[Tesselode]

So I've got a platform rotating based on the change in mouse position. And a ball. Yes it's Tilt. And if I rotate the platform fast enough, the ball will go right through the platform. Even if I'm using CCD. Or if I increase the thickness of the platform. Anything I can do besides limiting the speed of the platform?

[Jasoco]

A) Are you rotating the platform by setting its angle manually? Or by setting its impulse or whatever? Because if it's the former, there's your problem.

B) Have you tried setting the ball as a bullet?

[Tesselode]

A) Are you rotating the platform by setting its angle manually? Or by setting its impulse or whatever? Because if it's the former, there's your problem.

B) Have you tried setting the ball as a bullet?

A. I'm using setAngularVelocity.

B. Yes. Didn't help.

[bartbes]

Have you tried updating the physics world with fixed (small) timesteps?

[Tesselode]

Have you tried updating the physics world with fixed (small) timesteps?

Wouldn't that make the physics run at different speeds on different computers?

[Chief]

Wouldn't that make the physics run at different speeds on different computers?

No, just divide the delta time, or make a timer where you put delta time to 0 and when the timer is over it goes back to the original delta time.

[Tesselode]

That didn't work. Any other ideas?

[kikito]

I'd say you've reached the point where you must upload what you've got.

[Tesselode]

Well, I think I've pretty much worked around it now, but when I release Tilt r9, you can take out the code for limiting the platform rotation speed and see what I mean.

[pekka]

The Box2D manual isn't explicit about the issue, but it contains this highly suggestive sentence:

Box2D performs continuous collision sequentially, so bullets may miss fast moving bodies.

I take this to mean that it is possible for the fast moving non-bullet platform to skip over the small bullet body, since Box2D doesn't use CCD when it processes the platform's movement. I don't know what goes on for certain, since this hasn't come up for me. And I am not intimately familiar with Box2D source code...

Did you try setting your platform to be a "bullet" too? If not, it is worth a try.

Reference: http://www.box2d.org/manual.html