Exporting .mtl (with .obj) and multiple textures I tried search previously on this issue, but only came across issues where people were not having their .mtl file generated when exporting a .obj file.

I have been able to successfully exporting a .obj file with its accompanying .mtl file. The files seem to contain all of the relevant information, except for in the .mtl file:

newmtl test-material
Ns 96.078431
Ka 1.000000 1.000000 1.000000
Kd 1.000000 1.000000 1.000000
Ks 0.500000 0.500000 0.500000
Ke 0.000000 0.000000 0.000000
Ni 1.000000
d 0.000000
illum 2
map_Kd textures/test-01.png
map_d textures/test-01.png


In blender, for material test-material, I actually have two textures: test-01.png and test-02.png. Both textures have their boxes checked for active, I see both textures laid on top of one another, yet the exported .mtl only shows the first texture.

Is there an option I'm missing? Does .mtl not support the case where a material has multiple textures?

Thanks!
Wavefront doesn't support multiple textures. You can only add one diffuse/specular/normal/... texture per material. To export both, you'll need to bake them together to one texture.

See the specification here: http://paulbourke.net/dataformats/mtl/