Now that I have had a chance to get good look at the game assets (models/textures), and what techniques the game engine uses to draw models I think we need a dedicated technical thread.
For the time being, I will only focus on ships (but I will add interiors in some time). How to import or export them will also be added later, for now it's just how the game draws them. This info should be useful to those who want to create or modify models.
First, the available textures:
..._T01, RGB channels = Diffuse map
..._T01, Alpha channel = Optional, specular map (see below)
..._O01, RGB channels = Ambient Occlusion & dirt map
..._O01, Alpha channel = Optional, specular map (see below)
..._N01, RGB channels = Normal map (aka bump map)
The specular map is special, as it can be either in the alpha channel of the diffuse texture or the ambient occlusion texture. And it's not a required texture either. The game identifies which texture to use with the UnifiedRenderControler > UseSpecularFromDiffuse. All the other extra maps can also be turned on or off with this controller.
Below are shots with combinations of the maps enabled. The shots are rendered in 3ds Max, so this also shows I got all uv-maps in. Please note that I do not attempt to get the same look as in game, because the game uses shaders and all sorts of other stuff to make it look even better. The shots are made to show the difference.
Diffuse only
The model has only the diffuse map applied. It looks very plain. Shadows are calculated based on vertex normals only. The shadows depend in this case solely on the light sources in the scene. Since I have a big light above the model, there aren't much shadows seen at the top of the deck.
Close up:
Diffuse + Specular
Same as previous shot, but with the specular map applied. The specular map is used to determine how much light is reflected. The most obvious highlights are seen at the keel and midsection of the hull. It depends on camera angle and where the light sources are. At different angles the effect can be seen better.
Close up:
Diffuse + Specular + Ambient Occlusion/dirt map
With the ambient occlusion map applied, the whole ship is now darker. The ambient occlusion map is basically used to apply prerendered shadows to the ship. No light sources have changed!
The game uses a completely different UV-set (texture coordinates) for this texture, which is the most common problem experienced in today's modding, since no tool can export/import the additional set(s), yet!
Occlusion maps are often also combined with a dirt map. A dirt map is a map that has extra detail, dirt, rust, scratches, and what not. When blended with the diffuse map, this will add more variaty to the overal look of the model. The model no longer looks plain, and texture tiling is no longer very apparent. Look just below the turret base, you can see a whole lot of rust/dirt that wasn't in the previous shot...
You can also see the specular highlights better now.
Close up:
Diffuse + Specular + Ambient Occlusion/dirt map + Normal map (bump)
Not so apparent from a distance, the bump map provides yet even more detail. Instead of modelling small details like ladders, windows, doors, wires, rivets, etc with polygons, such details can also be faked by your graphics card. The bump map provides info what area 'sticks out' or 'falls into' a surface. In combination with light shining on a surface the graphics card will produce shadows which will give it a raised or lowered look. You can see the bump map in action better below in the close up shot, I overdid the effect a bit so you can see more clearly (compare also with previous closeup).
Close up:
More to come later.
PS: I am by no means a 3d expert, just for the record
