k3d/share/shaders/k3d_orennayar.sl:48:    float C1, C2, C3;
k3d/share/shaders/k3d_orennayar.sl:70:	C3 = 0.125 * sigma2 / (sigma2+0.09) * pow ((4*alpha*beta)/(PI*PI),2);
k3d/share/shaders/k3d_orennayar.sl:72:				  (1 - abs(cos_phi_diff)) * C3 * tan((alpha+beta)/2)));
