3dsMax exporter, Physical Material, and inverted alpha convention

Questions
1

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:

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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:

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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?

2

Adding @Guillaume_Pelletier in case he has a clue.

3

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?

2 Likes
4

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

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