I set up a sphere shape between 2 static planes. For the sphere and both planes, I set restitution to 1.0, linear and angular damping to 0, and friction to 0. The sphere velocity was set to (0,-5, 0). The sphere bounces between the two planes, but either slowly loses velocity until it eventually comes to a complete stop, or it slowly gains velocity until velocity reaches infinity. Is there a way to achieve perfectly elastic collisions?
Thanks