Ok, let me share my findings. While all of you are partially right, my -be it premature- conclusion is the following: I think the additional maps do indeed refer to the texture index array.
I've analyzed the chunk, and found that most models seem to
not use all of the texture coordinates (Vector2). So, basically, we have an texture index array that does not map into each and every texture coordinate array.
Now, if you think about it, this doesn't make sense. Why would there be more texture coordinates, then are actually used/mapped to each face.
This triggered me to search further. Enter the TMAP. Many of the indexes in the TMAP array (one or more maps possible), fill those holes! They refer to many of the remaining (yet unmapped) - but not all - texture coordinates. Great, so what now?
Well, it seems like the TMAP provides additional material info. For a ship with a wooden deck, the deck will cast/reflect light differently then the hull. Makes sense? But how does SH do this...
Many of the models have more than 1 texture. Ie.: take the Yamato: it has NBB_Yamato_T01.dds as the main texture. The NBB_Yamato_N01.dds is a normal map, and is used for bumpmapping. It is similar in layout to the T01 texture and could be directly mapped using the same texture coordinates. However, when we look at the NBB_Yamato_O01.dds texture, you can see it is a crazy image where the alpha channel is completely different from the RGB channels. It's very simple though, the alpha channel looks to me like the height map, and is also used with bumpmapping. The RGB channels however looks like a specular or diffuse map or maybe even another type of map they introduced to make a big surface look more unique by blending it. But since the layout of this texture is entirely different, we need new texture coordinates! Eureka? You tell me...
In case of interiors the same idea applies, although the TMAP appears to hold even more data. I haven't investigated this fully, but from what I see, interiors also use lightmaps, and maybe also both a specular and diffuse map. I will check this out later...
Anyway, I will try to use this data in my renderer (see
http://forums.ubi.com/eve/forums/a/t...5/m/9841082745 and
http://www.subsim.com/radioroom/showthread.php?t=110392) and see what the effects are (may take a few days/weeks though). I will try to use the TMAP indexes and only texture the ship with the RGB channel (without the alpha) of the xxx_O01.dds texture to see if my findings work.
If you have other ideas, think I'm absolutely wrong or whatever is on your mind, please keep 'm coming!
