k3d/share/shaders/k3d_shiftedmoontile.sl:61:	float circle1, circle2;  /* True if in circle1, circle2 */
k3d/share/shaders/k3d_shiftedmoontile.sl:64:	float d, d2;             /* Point distance from circle1, circle2 */
k3d/share/shaders/k3d_shiftedmoontile.sl:83:	circle2 = 1 - smoothstep (radius - fuzz, radius + fuzz, d2);
k3d/share/shaders/k3d_shiftedmoontile.sl:84:	mix_opacity = difference (circle1, circle2);
