VRayMultiSubTex and Refraction - Renders only Texture from first Slot 3ds Max

[Aysberg]

Hi, I see a strange effect in my renderings using VRayMultiSubTex and refractive materials.

In the sample you see stripes with different refractive materials, a first row of boxes with VRayMultiSubTex get ID from random by node handle (here the option does not matter) and a row of boxes in the back using four separate materials with the colored textures.

As you can see, some of the refractive materials seem to only use the VRayMultiSubTex in the first slot (blue), while others render correctly. Top to bottom (Default VrayMtl with 0,5 refraction, next from the mat library Glass_Tinted_Grey, Glass_Tinted_Black, Glass_Coated_Blue, Glass_Coated_Red).

Is this a known bug or by design? Since some materials work and the materials without MultiSubTex work too, I guess it's a bug.

I am using Max 2024.2, Vray 6.2 and Vantage 2.2.0.

[Alexander.Atanasov]

Hi Aysberg,

Can you please try to enable Shading graph for glossy/GI and see if it changes:

If not can you please send the scene for us to investigate?

Best regards,
Alexander

[vladimir.nedev]

By default shading graphs are disabled for glossy/GI rays.
VRayMultiSubTex is supported only as part of a shading graph.
If you have glossy refraction, after the first bounce, VRayMultiSubTex will no longer be computed.

You can enable shading graphs for glossy/GI rays, but it will most likely lead to a noticeable drop in performance.

Note that shadow transparency does not support shading graphs, so VRayMultiSubTex cannot be enabled in this case.

Edit: Alexander was faster and has a nicer screen-shot.

Greetings,
Vladimir Nedev

[Aysberg]

Alexander.Atanasov vladimir.nedev Thanks a lot. That did the trick. Now everything looks as expected.

The render time for a 4K HQ snapshot went up from 16.5 to 21.8 seconds in my case. That's acceptable