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AppGameKit Classic Chat / Box2D Physics

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Jimmy 9Toes
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Posted: 21st Nov 2011 21:12
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I'm trying to use Box 2D to do asteroid behavior where the rocks bounce off of each other. I'm assigning a velocity to the rocks and they're bouncing off of each othet just fine. But they eventually slow down to a crawl.

Is there a way to keep them moving at the same speed constantly? To possibly turn of this friction?

Yes THEE Jimmy9Toes
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bitJericho
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Posted: 22nd Nov 2011 11:48 Edited at: 22nd Nov 2011 11:50
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Are you storing the rock's velocity and direction as a vector or as x y and z values? Store them as a vector (a vector is a direction (like 0-360 degrees, and a speed) and don't allow the speed variable to change.


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Euphoria
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Posted: 22nd Nov 2011 12:33
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Not an expert but have you tried:

SetSpritePhysicsFriction( asteroid, 0 )
SetSpritePhysicsDamping( asteroid, 0 )

You might also want to look into the Restitution value as that affects its 'bounce' factor.
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baxslash
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Posted: 22nd Nov 2011 15:53
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Damping should be enough.

No need to edit friction as you probably want them to have at least a standard amount of friction for when they hit each other so they can set each other spinning.

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Jimmy 9Toes
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Posted: 22nd Nov 2011 16:54
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Thanks for all the tips. I'll give them a try.

Yes THEE Jimmy9Toes
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bitJericho
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Posted: 23rd Nov 2011 13:27
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Oh duh, should've realized you weren't doing physics yourself ^.^


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Paul Johnston
TGC Developer
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Posted: 23rd Nov 2011 23:26
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A restitution value of 1 means objects will not lose any energy in a collision. Interestingly values greater than 1 will make objects gain energy though collisions which can lead to some fun, if somewhat unstable, simulations.
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