k3d/share/shaders/k3d_corktile.sl:104:	float ingap = tile(s, t, tilewidth, tilewidth, swidth, twidth, gap, gap, sw, tw, so, to);
k3d/share/shaders/k3d_corktile.sl:119:	Ci = Os * (mix( Ct, Cg, ingap) * (Ka*ambient() + Kd*diffuse(Nf)) +
