blending bumpmaps in RT GPU

[vinced]

Hi Vladimir,

i am testing the demo of vray for modo and i need to blend several materials. Everything is blending fine, but bumpmaps as described in the documentation don`t blend together. I use groupmasks at the moment.
How would i do that?
Is this some limitation of GPU Rendering or will this be possible at some point in the future?
I have searched the forums but couldn`t find anything about this.
I have tried blendmaterials but that doesn`t recognize my texturemaps, just the vraymaterial.

Thanks for your help.

Greetings
vinced

[Robert]

Normally you would use multiply in Modo. Check that in Modo preview on bump output.. if that work, it should so in Vray too.
Even more interesting would be how to blend normal maps in Vray.. Modo currently can't do that.

[vinced]

Hi Robert,

this is not possible in vray at the moment.
The documentation says: "In RT GPU, only image maps can be used for bump mapping. Blending between them is not supported; only the top-most is used."
I wonder if this is will change in the near future and how i could do it now.
Maybe there is some kind of workaround.

Greetings
vinced

[vladimir.nedev]

I wonder if this is will change in the near future and how i could do it now.

There is some work being done in the RT GPU core to allow this.
Not sure if it will translate directly to V-Ray for MODO when I get the latest core changes, but it is a step toward allowing shader tree blending and layer/group masks to work with bump mapping.

Maybe there is some kind of workaround.

The only work-around would be to blend the bump maps in Photoshop and use the result as a single image layer in MODO.
Considering you are using group masks effects, that probably wouldn't be a solution for you.

Greetings,
Vladimir Nedev