RE: [Algorithms] collision reaction

[Kimberly P. <kim...@3d...>]

> 
> hi,
> 
> I'm trying to simulate collision reaction between two balls 
> (circles) in 2d.
> I want to simulate transfer of energy between the two balls. 
> I have a simple
> simulation running, but it seems to gain energy.
> 
> I probably have this all wrong, if so, could anyone tell me 
> where to find
> information on how to solve this problem properly?
> 
> this is the code I have so far, it's called when a collision 
> between two
> balls is detected.
> 
> 
> // get collision normal
> Vector normal = pBall1->position - pBall2->position;
> normal.Normalise();
> 
> // get dot product of ball1 velocity and collision normal
> Vector normVel1 = pBall1->velocity.Normalised();
> float dot1 = (normVel1.x * normal.x) + (normVel1.y * normal.y);
> 
> //calculate amount of energy transmitted from ball1 to ball2
> Vector transmit1 = normal * (pBall1->velocity*dot1).Magnitude());
> 
> // negate collision normal;
> normal.x = -normal.x;
> normal.y = -normal.y;
> 
> // get dot product of ball2 velocity and collision normal
> Vector normVel2 = pBall2->velocity.Normalised();
> float dot2 = (normVel2.x * normal.x) + (normVel2.y * normal.y);
> 
> //calculate amount of energy transmitted from ball2 to ball1
> Vector transmit2 = normal * (pBall2->velocity*dot2).Magnitude());
> 
> //subtract transmitted energy from current velocities
> pBall1->velocity-=transmit2;
> pBall2->velocity-=transmit1;
> 
> thanks,
> 
> robert
> 
> 
Here is a link to a site with a good discussion of the dynamics of two
colliding objects.

http://www.d6.com/users/checker/dynamics.htm

Kim