/**
* Find minimum depth and set mtd appropriately. mtd is the minimum translational
* distance, the vector along which we must move the box to resolve the collision.
*/
//TBD: this is only for right triangle surfaces - make generic
public void SetMTD( double depthX, double depthY, double depthN, Vector surfNormal )
{
double absX = Math.Abs( depthX );
double absY = Math.Abs( depthY );
double absN = Math.Abs( depthN );
if ( absX < absY && absX < absN ) mtd.Set( depthX, 0 );
else if ( absY < absX && absY < absN ) mtd.Set( 0, depthY );
else if ( absN < absX && absN < absY ) mtd = surfNormal.MultNew( depthN );
}
// TBD: too much passing around of the Physics object. Probably better if
// it was static. there is no way to individually set the kfr and friction of the
// surfaces since they are calculated here from properties of the Physics
// object. Also, review for too much object creation
public virtual Vector ResolveCollision( Vector normal, Engine engine)
{
// get the velocity
Vector vel = curr.MinusNew( prev );
double sDotV = normal.Dot( vel );
// compute momentum of particle perpendicular to normal
Vector velProjection = vel.MinusNew( normal.MultNew( sDotV ) );
Vector perpMomentum = velProjection.MultNew( engine.CoeffFric );
// compute momentum of particle in direction of normal
Vector normMomentum = normal.MultNew( sDotV * engine.CoeffRest );
Vector totalMomentum = normMomentum.PlusNew( perpMomentum );
// set new velocity w/ total momentum
Vector newVel = vel.MinusNew( totalMomentum );
// project out of collision
curr.Plus( mtd );
// apply new velocity
prev = curr.MinusNew( newVel );
return newVel;
}