Vray "material select render element" output material ID or flat color ?

[bigbossfr]

Hi,
I have some objets with VrayBlendMtl. In the VrayBlendMtl, i have VrayMtl "blended" with masks (like in one mesh, i have a wood material and a metal material. A mask separates all.)
What the problem ?
The problem is to output mask ID.

If i use a "material select element", i haven't the alpha of the "material", and i have "one" material on the image (like the wood).
It is impossible to use this on a production (because no alpha).
If i create a material ID on a "sub material" of the VRayBlendMtl, it is doesn't work.

What is the solution ?

1) First solution : all materials ID or multimattes ID of "sub materials" of a VRayBlend can work with Multimatte element (it is the best solution !)
or
2) Material select can output material ID (not the best solution because we will have one mask for one element)

There is the same problem here : http://www.chaosgroup.com/forums/vbu...ght=multimatte

Currently, we don't know how to solve this problem.
Thank you !

[vlado]

The original idea for this was to use the material ID color attributes on the sub-materials (and not the integer ID numbers) together with a Material ID render element. This seems to have some issue currently, but I should be able to fix it relatively easily.

Best regards,
Vlado

[bigbossfr]

The problem to use the material ID color attributes on the sub-materials is, if we want to output lot of masks in red/green/blue color (with mutimattes), we can not (we can output 3 sub-materials maximum with this 3 colors).

[vlado]

Ok then. In that case, would it help to add a "mask" mode to the VRayMtlSelect element which will output a single floating-point channel with the alpha for the chosen material?

Best regards,
Vlado

[bigbossfr]

Yes, this can be a solution ! Not the best because we will have one mask for one image (and not 3 mask for 1 image), but if it works and it is more easy for you, it will be great.
Thank you Vlado.

[vlado]

Yes, this can be a solution ! Not the best because we will have one mask for one image (and not 3 mask for 1 image), but if it works and it is more easy for you, it will be great.
Thank you Vlado.

Ok, I'm working on this now. Btw the mask channel is just a single float, so if you use multichannel .exr files, it will be pretty much the same as using three colors.

Best regards,
Vlado

[sersia]

Ok then. In that case, would it help to add a "mask" mode to the VRayMtlSelect element which will output a single floating-point channel with the alpha for the chosen material?

Best regards,
Vlado

Hi Vlado,

Could I use a "mask" mode with VRayMtlSelect element? Is it done already? Or is it still in progress?
It might be great if I could get the alpha for the chosen material.
Because sometimes I need a pure RED for VRayMultiMatte element with refraction but there is a problem with that for me.

Here is the example.

If I make a mistake or misunderstanding, please give me an advice for that. I think I am missing something else for that.

Thank you for all your kindness.

Best Regards,
Sangho Jung.

[vlado]

It is not done yet, but we are working on it.

Best regards,
Vlado

[bigbossfr]

Bump.....
I have a lot of sub material with black and white mask (wood, metal, etc etc) and i can not ouput multimatte ID.



The result of the multimatte ID renderElement is black.
And if i add color in materialID, materialID renderElement is white.

Is it hard to fix please ?

[bigbossfr]

After some research i did not find a work around.
What i see is :
1) If i add a material ID on sub materials of a VrayBlend, and set a color, all colors of material ID attribute of all sub materials are added. The conclusion is the material ID attribute of sub materials do not respect the "blend amount" attribute of VrayBlends. All are added. I don't know if it is diffucult to fix.
2) Multimatte ID of sub material is completely ignored.

The question is : what is the solution ?

I am completely bloked.

Thanks.

[bigbossfr]

Hi,
Any news about this please ?

Thanks.

[paulDryzen]

Heya,

if I use materialselect passes I output the blend amount input into an extraTex, takes some rendertime but is sometimes the only way to make it work in comp.

Since most of the time the blend amount ist just a simple color you can put 3 of them in one extra texture.

Hope this helps a bit.

Paul

[bigbossfr]

Hi,
Yes, but if you do this, you will have your blend amount on all your image....
And user attributes do not work into proxies.

But thank for the suggestion.

[bigbossfr]

Ok, i have create a script (8h to find the algorithm...) which create on the fly (when Vray is rendering, nothing is done on the scene) material ID (and it works with blend materials, vrayBump, multi blend....) in Python. Each material have unique color based of the name of the material, and the script know if you use the material many time (in vray blend, in vray bump, direct on the mesh, etc etc...)), you will have the same color.
I will include this script in my Vray Arsenal.

Done.