Hi ,

Can anyone tell me how you would go about calculating spherical collision patterns? I've been playing a 3d pool game that is very realistic and I am amazed at how life-like the ball collisions are.
Any info on this subject would be greatly appreciated.

Thanks

c20

Everything except the collision-detection should be pretty basic.
I think that if ball A hits ball B at point P on the surface of A, the direction of change in momentum on B will be normal to P on A. The magnitude of change will be proportional to the momentum of A times cos(v) where v is the angle between the momentum-vector of A and the normal through P also going through the center of A.

I'm not sure it works like this tho, but it seems reasonable.

Im no mathematician although the subject fascinates me so you may have to help me out here a little if thats cool. I think I understand what you are saying and it seems reasonable, however it must get massively complicated when 'spin' is applied to ball 'A'.

There must be a standard algorithm to calculate all possible outcomes of the collision of two spheres and there subsequent trajectories after collision?

You maths guys amaze me incidentally :tup:

Yeah, wow, i didn't think about that.
Working out a solution for the spin imparted on impact can be pretty complicated depending on how real you want the situation to be. I'm sure there's a good approximation tho that isn't so complicated. It might work if you let a fraction of the kinetic energy of the balls disappear at each impact and then let a fraction of that, depending on sin(v), be transferred into "rotational energy".
If you really want to do this, there's a part of highschool-physics that teaches what happens when two objects collide. What an elastic and unelastic collision is, etc. It requires only basic algebra.

It just fries my head. How can anyone be clever enough to work this out to come up with a completely accurate game???
Thanks Anders for taking the time to ponder this with me.

I found a really good link if anyones interested. Gives the whole algorithm.

http://www.gamasutra.com/features/20020118/vandenhuevel_01.htm

Peace

20c