// Relative velocity at contact
Vector2f relativeVelocity = new Vector2f(b2.getVelocity());
relativeVelocity.add(MathUtil.cross(b2.getAngularVelocity(), r2));
relativeVelocity.sub(b1.getVelocity());
relativeVelocity.sub(MathUtil.cross(b1.getAngularVelocity(), r1));
// Compute normal impulse with bias.
float vn = relativeVelocity.dot(c.normal);
// bias caculations are now handled seperately hence we only