Graphical feature requests

[joevenzon]

I'm going to back track here and tell you stuff you already know for a moment, bear with me. The specular map lets you define specular color (technically, the fresnel coefficients at zero degrees) in RGB and shininess (technically a microscale roughness term) in A. For car paint you're going to pretty much always want a white specular color (depending on the paint) no matter what the diffuse color is. Different types of paint could use different shininess values, though, like you mentioned for glossy versus more matte. Different parts of the car get mapped to different parts of the diffuse and specular textures. The diffuse texture (for cars) has diffuse color in RGB and a "this is car paint" mask in the A. The shader takes the selected paint color and applies it to the areas marked as car paint in the diffuse texture to get the final diffuse color. Breaking up the mesh isn't necessary to get different graphical effects because everything reads out of a texture and it gets put through the same shader regardless. Parts of the car that have a different material (think underbody, chrome exhaust, vinyl graphics, etc) will need to have different shininess values from the rest of the car. If we wanted to do something similar to the paint selection (although we could limit the choices if desired) but for shininess, we could do that by re-using the car-paint mask from the diffuse alpha channel to determine which areas to use a specified specular shininess value. That way you wouldn't have to make more than one specular map if you didn't want to.