3dsMax exporter, Physical Material, and inverted alpha convention

Hi! My setup is 3dsMax2019, last exporter, and glTF format.

Using an Arnold Standard Surface material, I haven’t any issue using an albedoTexture with alpha :+1:t5:


But if I use a Physical Material, alpha convention isn’t the same (as gltf I suppose?), and the result once in BJS is that alpha is inverted:

I’ve read the doc’ and also seen this Github issue, but can’t find if it’s possible to get correct glTF/BJS alpha convention using this Physical shader.

So, is there a workaround or should I ban the use of Physical Material?

Adding @Guillaume_Pelletier in case he has a clue.

Hi @Vinc3r,

I believe the alpha transparency convention is different between the material models. From what I gather, Physical Material uses Transparency, where 255 = transparent, 0 = opaque, while Arnold Standard surface uses opacity where 255 = opaque, 0 = transparent.

Though I am not 100% on this, however this seems to align with your findings. Are you able to render with both materials using the same map in the same scene?


That makes sense, thanks.
I’m not used to Arnold so here a very simple and ugly render:
Arnold Standard Surface to the left, Physical Material to the right