k3d/share/shaders/k3d_watercolor.sl:24:	float sinthetat = sin(thetai)/nSnell;

k3d/share/shaders/k3d_watercolor.sl:25:	float thetat = asin(sinthetat);

k3d/share/shaders/k3d_watercolor.sl:33:		float fs = sin(thetat - thetai) / sin(thetat + thetai);

k3d/share/shaders/k3d_watercolor.sl:34:		float ts = tan(thetat - thetai) / tan(thetat + thetai);

