CS121 Project 2
Collision Response Vector
Suppose a particle moving with constant velocity vavg collides with a surface. The response
velocity is d[vavg - 2(vavg • n)n], where
d is a damping factor and n is the surface normal.
To see this, first consider the vector u=(-vavg • n)n shown in the figure below.
Next let w = vavg + u = vavg - (vavg • n)n.
Then the reflected vector is -vavg + 2 w = -vavg + 2(vavg - (vavg •
n)n) = vavg - 2(vavg • n)n.
