This is an animation of a billiard with a flat cusp. The boundaries of the billiard table are the curves \[ x = 1 \qquad \text{and} \qquad y = \pm \alpha x^\beta . \] For the purpose of this animation, we fix \(\alpha = 0.5\) (so the table fits in the square \([0,1] \times [-0.5,0.5]\)).

The particle is a point (radius is zero); it is displayed as a disk with positive radius so that it can be seen.