k3d/share/shaders/k3d_graphic_lines.sl:106:	vector Nf_highlight;
k3d/share/shaders/k3d_graphic_lines.sl:110:	Nf_highlight=faceforward(normalize(N_highlight),I);
k3d/share/shaders/k3d_graphic_lines.sl:128:	illumcolor_highlight=(Ka_highlight*ambient()+Kd_highlight*diffuse(Nf_highlight)+Ks_highlight*specular(Nf_highlight,V_highlight,roughness_highlight));
