Turns out that the name doesn't accurately describe what it does.
It is correct for images that come with their own palette or are true color.
But for images using the game palette it doesn't use the red channel to determine translucency but the palette index! Ugh...
This means it cannot be done with a simple operation in the shader because it won't get a proper source image. The only solution is to create a separate texture.
- remove thing color from lighting calculations.
- implement alpha textures and inverse sprites for infrared as texture modes. This still requires some handling for the alpha texture mode for non-shader rendering because there is no way in the fixed pipeline to do it. The inverted texture effect can be done with a texture combiner.
- fixed: ThingColor for sprites was set in the wrong place. It must be in the Process function, not in the lighting calculation.
- added functions for isolated calculation of sprites' dynlight color.
