private void penetration(Body body_a, Body body_b)
{
// early out, cant be a bubble merge
if (body_a.is_static || body_b.is_static)
return;
if (body_a == player.body)
if (TryMerge(FindBubble(body_b)))
player.num_collected++;
if (body_b == player.body)
if (TryMerge(FindBubble(body_a)))
player.num_collected++;
}