Wavefront .obj .Mtl Structure

Question

I'm trying to load a .obj File in Java with lwjgl without using any Library doing this. I created a Class to load the Model without Material and textures. That's easy. But now I want to laod the Model with Material and textures. My Problem is the knowledge about the .mtl file. I didn't find any explination of the .mtl File anywhere. But I need to know what these Ka, Kd, Ks, Tr,Ns and map_... Things mean. Maybe somebody know a good explination of it somewhere in the web?

And my second question is about the Texture-Coordinates of Textures in the .obj File. I don't understand how to draw a 2D-Texture on a 3D-Model with 2D-Texture-Coordinates because you need a 3rd value in a 3D Room because a 2D Plane in a 3D Room also needs 3 values per Vertex.

Answer 1

I think this is a reasonable explanation:

MTL File Specification