[pymunk] Creating objects inside a circle

[BilbyCoder]

[slembcke]

Circles are a solid shape, you cannot put objects inside of them.

If you want to do that, you will have to make an approximate circle out of line segment shapes.

[BilbyCoder]

Thank you. Obvious in hindsight really. I presume the behavior of the smaller circles moving to the side is them being "pushed out" of an intersecting collision.

[slembcke]

[Knertified]

I have the same problem and tried creating a about 8 cpSegmentShape's to build an Octagon. I drop a bunch of circles inside and they all shoot outside. It's the exact same problem when using cpCircleShapeNew. I don't think it matters either way. Any ideas?

Thanks!!

[slembcke]

Are you doing anything to prevent the collisions with the circle? If you allow the objects to collide with the circle, they will get pushed out. Polygons and circles are solid objects, so they will push other objects out of themselves.

[Knertified]

I somehow mixed up something. I think I was still drawing the circle and the line segmented circle at the same time lol. The line segmented circle works almost perfectly. For some reason when a lot is going on... which doesn't take much on the iPhone (25 or so squares in a 20 sided polygon), the squares start to fall out. For example, when I get under about 20fps, it's like the system isn't quick enough to check for collisions and lets them slip through. I'm going to do some more forum searching to see if I'm missing something.

Thanks,
Mike

[slembcke]

Are you using a variable size time step?

Chipmunk works with variable sized time steps, but I strongly recommend that you don't.

[Knertified]

The only timing information I can find is this:
[[Director sharedDirector] setAnimationInterval:1.0/60];

Now, I understand that is really a cococs2d method so I suppose it's possible cocos is doing something weird and I might need to dig a bit deeper. I'm not sure if your familiar with cocos or not but I'm basically just modifying the Chipmunk_Accel.m file and leaving the framework intact.

A side note, I changed the squares to circles and it can handle almost 2x as many circles before I start seeing problems... About 50. It's like the iPhone just stops dead for a second and all the smaller circles just blow out of the larger segmented circle. After that the FPS shoots way up because there are only 10 or so left. lol.

[slembcke]

Hmm. Not familiar with Cocos. It's possible that it's using variable timesteps.