Just a list which shader uses alpha-channel for what. It’s not all of them, only ones I used & figured out.
- Most shaders (ksPerPixel, ksPerPixelReflection, ksPerPixelAT, etc) uses alpha-channel of txDiffuse for transparency (but it could be seen only if BlendMode isn’t eOraque), pretty obvious.
- But not NM shaders (ksPerPixelNM, etc), they ignore alpha-channel from txDiffuse and use alpha-channel of txNormals. I suppose this way it’s easier to colorize some stuff later in skins (you don’t need to worry/can’t change alpha-channel).
- And not MultiMap shaders (such as ksPerPixelMultiMap, ksPerPixelMultiMap_damage_dirt, ksPerPixelMultiMap_NMDetail), they use alpha-channel from txDiffuse to see where txDetails should work and where shouldn’t. And also, they use alpha-channel from txDetails: the more brighter gets alpha-channel of txDetails, the more specular size (or less ksSpecularEXP) will be. Usually used for flakes effect (take a look at those txDetails textures, often their color is solid, only alpha-channel is different).
- Special case is ksPerPixelMultiMap_AT: it uses alpha-channel of txDiffuse as other MultiMap shaders, but also it uses alpha-channel of txNormals, as NM shader. So, with this shader you could easily implement colorized rims very useful way: only one 8×8 texture will colorize static and blurred rims at the same time! And also, of course, with baked shadows and stuff. If you want more details, check out RX-7 sources.
- Two special shaders — ksTyres and ksBrakeDisc — uses alpha-channel of txDiffuse as specular and reflection level. Perfect to make holes in brake discs and even overall occlusion.