k3d/share/shaders/k3d_oakplank.sl:153:  float edgedisp = smoothpulse(0, edgewidth, plankwidth - edgewidth,
k3d/share/shaders/k3d_oakplank.sl:155:  edgedisp *=
k3d/share/shaders/k3d_oakplank.sl:158:  float disp = -wood * divotdepth + groovedepth * (edgedisp - 1);
