Blending Materials

[Jim Meston]

Hi

I am trying to blend a standard material and an sss material to see I can get a better effect than refraction roughness and translucency in the standard material.
Really struggling to find a BRDF blend node.

Any help appreciatred.

Jim

[chakarov]

is this what search https://docs.chaosgroup.com/display/VRAYHOUDINI/Blend ?
But you should set materials count to use in "BRDF Count" parameter

[Jim Meston]

Ah great. I was looking for a node with yellow brdf inputs exposed. I didn't realise they had to be manually exposed. Thanks again.

[Jim Meston]

So I have a setup that is working great, just wondering how you might go about rotating UV's on a per instance basis.
Obviously adding to vectors is translation, multiplying is scale, is there a way of implementing a rotation matrix in a vray shader?

[Gosho.Genchev]

Currently not but it's become a pressing matter with your request in addition to another person asking a few days ago. We're looking into a way to handle this in a user-friendly manner - I'll ping you as soon as we have something.

Best regards!

[Jim Meston]

I am guessing there is no may to use houdini nodes to create a rotation matrix etc. Or an unfriendly way to do it vray nodes?

[Gosho.Genchev]

So I have a setup that is working great, just wondering how you might go about rotating UV's on a per instance basis.
Obviously adding to vectors is translation, multiplying is scale, is there a way of implementing a rotation matrix in a vray shader?

I was hoping we can figure out a way to do this with a matrix that you can bring from the attributes in SOPs, or generate in VOPs - it will definitely remain on the bucket list but it's too convoluted at the moment.

What I can suggest is using this:


Source: https://en.wikipedia.org/wiki/Rotation_matrix

I've attached a Houdini file containing a shading network that you can pack in a Digital asset in case you find it useful. It's here:
https://drive.google.com/file/d/1ZDT...ew?usp=sharing

It produces this:




Hope that helps!

[Jim Meston]

Wow !!! I will take a look thank you very much you are a genius.

[Gosho.Genchev]

I've forgotten to hook up the "in_rot_angle" null to the "cos_angle" VOP.

I've updated the file. Sorry about that - I was trying to name stuff and give it to you such that it doesn't look like soup of noodles.

Best regards!

[david.anastacio]

Hi,

Jim Meston , any reason why you just can't use the "rotate_uv_tex" in the image node?
I just plugged in the angle paramater in the file to it and you get it. I'm doing this all the time in my assets to, now by default they carry an "id" parameter which is just a random integer by connected primitive taht we can use for such things:



This method Gosho.Genchev came up with will be usefull for apllying random uvs to other nodes taht don't have the "rotate_uv_tex" input.

Best,
David.

[Jim Meston]

I can't remember actually, it was for a load of instances where we were adding uvs to a world space rest position to get the uvs to to stick to the animated objects, so there was no texture sliding with the "deforming" geo.
I am guessing that the uv & rest computations in this form excluded you from just plugging some noise into the rotate, but thinking now I suspect there is a method.

[Jim Meston]

Hi David,

it was for a situation not too dissimilar to this (see image). Previously this was for mapping procedural noise onto animating instances, so adding a rest position to the object UV's was necessary.

Also I was storing @restnoise on instanced objects, which came from the parent points. So in this setup it seemed logical to do it this way.
I haven't since really thought about a driving the inherent texture transforms, I can't see a way to split vectors/colors into components.

[Gosho.Genchev]

I haven't since really thought about a driving the inherent texture transforms, I can't see a way to split vectors/colors into components.

There are the Color Channel and RGBA Combine VOPs (we wanted to rename them Color to Float / Float to Color but that would confuse veteran V-Ray folk so we decided not to do it).

Hope that helps!

[Jim Meston]

I was looking for Color to Float / Float to Color

[Jim Meston]

Hi,

Jim Meston , any reason why you just can't use the "rotate_uv_tex" in the image node?
I just plugged in the angle paramater in the file to it and you get it. I'm doing this all the time in my assets to, now by default they carry an "id" parameter which is just a random integer by connected primitive taht we can use for such things:



This method Gosho.Genchev came up with will be usefull for apllying random uvs to other nodes taht don't have the "rotate_uv_tex" input.

Best,
David.

[EDIT]

I finally remember, it was because I was rotating a procedural noise on a per instance basis (10000s) which were being animated through world space. So adding @rest to @uv and then doing some moving and scaling of those attributes (+* etc), obviously there is no simply way to rotate without using the awesome method described by Gosho.Genchev