k3d/share/shaders/k3d_bubbles.sl:15: float distance2point;
k3d/share/shaders/k3d_bubbles.sl:22: distance2point = distance(myPoint, myCenter);
k3d/share/shaders/k3d_bubbles.sl:23: if (distance2point <= radius) 
k3d/share/shaders/k3d_bubbles.sl:24:    magnitud = sqrt((radius * radius) - (distance2point * distance2point));
