k3d/share/shaders/k3d_rustymetal.sl:2: * rustymetal.sl -- metal with specks of rust
k3d/share/shaders/k3d_rustymetal.sl:7: *   rusty, shade like rust colored matte, and also make it bumpy (like
k3d/share/shaders/k3d_rustymetal.sl:15: *   rusty - 0=no rust, larger for more rust, 1=completely rusty
k3d/share/shaders/k3d_rustymetal.sl:16: *   rustbump - controls the "bumpiness" of the rusty areas.
k3d/share/shaders/k3d_rustymetal.sl:44:k3d_rustymetal (float metalKa = 1, metalKs = 1, metalroughness = .1;
k3d/share/shaders/k3d_rustymetal.sl:48:	    float rusty = 0.2;
k3d/share/shaders/k3d_rustymetal.sl:53:  point Nrust;                 /* perturbed normal for the rusty areas */
k3d/share/shaders/k3d_rustymetal.sl:57:  float rustiness;             /* Result: how rusty is this point? */
k3d/share/shaders/k3d_rustymetal.sl:71:  /* If it's rusty, also add a high frequency bumpiness to the normal */
k3d/share/shaders/k3d_rustymetal.sl:77:  rustiness = step (1-rusty, clamp (sum,0,1));
