Assimp Material node usage?

I am trying to import a .obj model using the Assimp nodes, and I’m having some problems. The meshes come in fine, but the material node does not seem to be outputting the correct alpha for a material (alpha is always 1), and I have no clue how to do the case where a model has mixed colors and textures.

Concerning the alpha, the .mtl file is specifying “d 0.1000” (d = dissolve) - I tried changing that to “tr = 0.1000” (for tr = transparency) but the alphas were all still 1.

Concerning the use of textures, the .mtl file defines three materials, one of which references a texture file. The Material node is outputting only one filename - though there are three materials defined.

So I am assuming that the Material node “Texture Count” pin is an index into the output of the “Texture Path” pin, but it’s off by one, and even with that, how do you handle selectively sending in textures to another node in a slice-wise manner? If you try sending in a spread of strings to FileTexture, with empty strings for no textures, the spread of output textures overrides the material color in nodes like GouraudDirectional. Creating an empty texture using Cons (Node) does the same thing.

So HOW the heck to do this? I can’t figure out any way to feed a “Nil” texture in a Spread where one is not to be used. Any example or help greatly appreciated! Attached is a zip with an example patch and model files.

Bonus Points! Can someone explain how to use the Material node “Texture Type”, “Texture Operation”, and “Texture Map Mode” output pins?


Test patch and model (352.0 kB)

Imho, main issue here is that you provide just one bitmap, and create an “invalid” texture through cons node. I’d say that you should either create materials with proper bitmaps for each material (and this would be good because everything goes automatically) or load textures and rearrange them to map corresponding meshes or create them in vvvv and rearrange them.

See attached.

assimptest_mod (5.0 kB)