k3d/share/shaders/k3d_eyeball.sl:16: *   pupilcolor - color of the pupil (opening)
k3d/share/shaders/k3d_eyeball.sl:53:	 color pupilcolor = 0;
k3d/share/shaders/k3d_eyeball.sl:124:  Ct = mix (pupilcolor, Ct, pupilstat);
