Multimatte isMatID not working within VrayBlend outside VrayMtl

[kagemaru]

As written in the subject, the very useful feature of isMatID of the Multimatte render elements works just if you use VrayMtl shader and no one else.
Tested with VraySSS2, VraySkin, VrayLightMtl, etc, 3dsMax 2016 with Vray 3.20.03.
Cheers,

fede

[Zdravko.Keremidchiev]

This seems to work fine on our side. Could you please attach a simple scene or send it to support@chaosgroup.com

[kagemaru]

File sent.
I'm attaching here the output with VrayMtl, VrayFastSSS2, VrayLightMtl and VraySkin.

[Margarita.Stoeva]

Hello, fede

I can see that you have asked something similar about VRayHair in VRayBlendMtl before. I understand what you want to do but I'm not sure if this is an accurate behavior that you wish regarding the blending itself. You could use VRayExtraTex render element with the map that you use for blend amount instead and get a proper mask.
The VRayBlendMtl has its own MtlID and it is used in MultiMatteElement with any material I tested linking to it (when it is not VRayMtl) and it seems logical this way. If you can get me a scene that requires MultiMatte through blend, I could see why you need it. Excuse me if I'm wrong.
I appreciate your feedback, thank you!

Best regards!
Margarita

[kagemaru]

Hi Margarita and thanks for the quick reply.
Of course you are right about the VrayExtraTex and this is sometimes what i do to get my mask. Vray always gives us a way back!
The thing is that it happened several times here where we had characters/fluids/primcurves/etc that used one single mesh but different shaders attached and it was a very quick and efficient way to just assign a vrayblend and the isMatID feature.
For example i'm now rendering a fluid simulation where different materials are present (2 chocolates and milk) or maybe this character that had 2 very different fur shaders assigned.
Doing 3 channels mask with a VrayExtraTex requires me to create a specific additional map with a bit more work. Of course this is no show stopper bug at all!
I'm asking just because i don't understand why the VrayMtl would work while any other shader won't.
Cheers,

fede

[Zdravko.Keremidchiev]

Please note that due to the nature of the VrayBlend Material it is not possible to generate sub-material masks with MultiMatte render element from it.
Therefore it is best to use the VrayExtraTex workaround instead.