k3d/share/shaders/k3d_brick.sl:60:  swidth = 1.5 * max(filterwidth(s), MINFILTWIDTH) / BMWIDTH;
k3d/share/shaders/k3d_brick.sl:61:  twidth = 1.5 * max(filterwidth(t), MINFILTWIDTH) / BMHEIGHT;
k3d/share/shaders/k3d_crayon.sl:50:#define MINFILTWIDTH 1.0e-6
k3d/share/shaders/k3d_crayon.sl:51:#define filterwidth(x)  max (abs(Du(x)*du) + abs(Dv(x)*dv), MINFILTWIDTH)
