k3d/share/shaders/k3d_grids.sl:75:normal G1_Nf = faceforward(normalize(N), I);
k3d/share/shaders/k3d_grids.sl:97:Ci = (blend_val*G1L1_Ct+(1-blend_val)*G1L2_Ct) * (ambientcolor * K_ambient * ambient() + K_diffuse * diffuse(G1_Nf)) + 
k3d/share/shaders/k3d_grids.sl:98:specularcolor * K_specular * phong(G1_Nf, G1_V, 1/roughness);
