Sorry about the network's line colors on this one; I know it might be difficult to tell what is a "connection" and what is something I'm circling (squaring?) in the diagram. But, I was running out of colors! This is a demo/tutorial of/on my 'little' custom shader network!

Yes! The custom shader network! This is how I apply shaders to the model in particular patterns. It is composed of 3 Subsurface Scattering Shaders (so it uses Mental Ray for its renders, because Mental Ray makes everything look good :P ), 2 Fur Textures, and a number of fur maps and other masks. I pipe there various outputs into one another or use blend utilities to combine them. It's easily extensible, so I can just keep layering on more portions that are shaded differently (I even added a new map for applying the "gums" SSS to the interior of the mouth) just by adding in another blend utility. Even better, its super easy and quick to produce an entirely different color scheme for new colors. Just adjust a few color parameters and maybe draw new new fur maps if I want the pattern of the fur to be different. Here's how the shader network works:

1. This white base fur texture is special variation of the base fur texture. See #2 for more info on the base fur texture. This provides a different, dynamic property for the 2nd cloth texture node's Gap which is decided by a sampling utility's ray direction property. That is to say, whether the Gap value for a particular pixel is white, black or somewhere in between is dependent upon the direction of rays of light intersecting that particular pixel on the surface. This adds a certain je ne sais quoi to the coloration of the shaders further down the chain. It's hard for me to explain, but I like the result; it made things "pop" more, but the difference wasn't significant enough to provide comparison images. Check out the #2 for how these are used by the shader network.

2. OK! The base fur texture! This is two 2D cloth textures with different properties and proportions, with one's output piped into the parameter that defines the strand's (or in my case, the inside of a bundle of fur) color. (Don't confuse these with cloth simulation or Fur simulation, this is just a generated texture.) It's black and white because its used similarly to the fur maps described later. They are used as blend parameters for blending between SSShaders and their gamma-shifted light and dark variants. The blend utility is very simple: two colors are blended together to create an output color with the proportion of the two colors defined by a 0-to-1 number (so, if the two colors were white and black and the blend was 0 the output would be white. If the number was 1, the output would be black. If the blend was .7, the color would be a darker shade of grey.) The key is that, like just about every parameter, the blend parameter can be piped outputs of other things. In this case, the base fur textures are piped in. This means, whatever shade the texture is at a particular pixel is converted from the greyscale to a number from 0-1 and decides the proportion of the colors in the blend! Simple, but extremely powerful: the blend utility is the key to this entire shader network.

3. This is the base MISSShader: the one applied to most of the body, in the case of Gravitas, the green one. A MISSShader is a Subsurface Scattering Shaders that kind of approximates the semi-translucent nature of skin, but it can be used differently to create many beautiful looks. This one provides most of the non-color parameters to the other MISSShaders to maintain uniform properties for things like how shiny it should be. There are a TON of parameters to tweak and tinker with here and I can't help but be drawn to do so, whenever I'm producing a new color scheme and they propagate down to the other MISSS automatically. Like the other two MISSS, it is also fed into two Gamma-shifting utilities that provide a lighter and darker color output. These three outputs are then blended together, using the base fur textures as blend parameters, adding some variety to the color of the model, as well as giving it the fur-like pattern of the texture. Sadly, I don't really recall exactly why I need to use two base fur textures. I know its important, but I can't quite remember. The White on has a bit extra that also adds some variety to the coloration. Future changes may include piping the base fur textures into some of the MISSS parameters that determine the shininess, so that the darker streaks in the fur will be less reflective; this should help make them "pop" even better!

This number and the other mapped shaders also have model head shots on the far vertical that depict what they look like mapped together without the base textures to add variety and the fur pattern. Comparing the straight MISSS of 3 to the combined one, you can see it looses a certain something. This is because they are all piped into the diffuse property of another Mental Ray shader. One of these days, I'm going to play around with what I choose for the last shader and try to carry through a more faithful final result, but for now this last shader provides a few other useful properties not available to the MISSS themselves. I just forget what they are or how I use them. Kind of like that green plasma looking texture I placed a '?' next to. It provides the output of the green plasma as a color tinting the reflection color of the final shader, but only where the black fur MISSS exists. I'm not sure, but I think this means that scene elements reflected in the black fur will have a slightly greenish hue to them in a plasma-like pattern. Probably something I cooked up to add to the other-worldliness quality I'm shooting for, for the Dr. Gravitas character.

4. The white MISSS, for the chest, tail tips, muzzle, etc. As is squared in the diagram, it also has two gamma-shifts. You can also see its fur map. This is a ZBrush polypaint painted texture, laid out according to the UV map, that defines where this MISSS should be applied on the model! Black means apply and white means don't. Piped into a blend utility as the blend parameter, with two MISSS or chains of MISSS as the colors. Simple! The results can be seen on their own without fur pattern using the textures, on the center right.

5. The black (really, bluish) MISSS. For the ear tips, socks 'n gloves. Works just like the other MISSSs, with its own Fur Map.

6. The nose and lips. A 3D generative texture gives a simple black Lambert shader a grainy pattern. Applied just like the MISSS, with a map.

7. A little dark highlighting around the eyes. It was much more noticeable in older versions (like the one depicted in this old scrap. Now its applied lighter, by providing more grey and less black in the map. I use the darker gamma-shift of the black MISSS (without base fur patterning because that'd be redundant) to blend into the basic green MISSS. This could be used like a kind of heat map for subtle shading variations on parts of the body, like around the mouth or anywhere we want a deliberate alteration of the tone of the shader.

8. New addition, this is a Gums-colored MISSS (reddish with more blue/purple subsurface scattering) specially applied to the interior of the mouth, using yet another map-driven blend utility.

9. The final composite! All rendered all together automatically! An unlit, basic render. You can see there's a couple odd spots of gums MISSS; this is an issue with the UV.


Check out more final composite views in this scrap and a final render version, using the full ray tracing, caustic, global illuminating power of Mental Ray! There maybe a lot left to do on the topology of the model, but once I do that, rebuild its UVs and paint new maps, this finished custom shader network will plug right in and be ready for more rendering! Fur maps can even be redrawn any point after the UV is finalized without having to recreate an entire colored texture! (However, new UV means new maps. So, that's a down side.) The fur maps can also serve the same utility in future aspects of the model, like specifying where one kind of realistic fur simulation is applied versus another, so I have patches not just with different colors but different densities and strand heights and all those other wonderful parameters that come with using a real fur simulation instead of this ad-hoc texture solution.