Q; CarPaint shader, Flake parameters and float nodes?

[Rork]

Hi,

I ran into something that is a bit odd, or a massive pebkac. Still human here..

I have a VRayBlendMtl shader that is hooked up to multiple carpaint shaders, all neatly mixed with masks etc. to split up various parts of a Alembic proxy. Works great.

What I tried to do is set up a small set of float nodes to drive the Flake density, Flake Scale and Flake Size. So you don't have to chance values again for all the shaders with every tweak.
But he moment you set it up like this, the flakes don't render anymore.

I'm running similar setups for bump scale and UV values, and those work just fine.

So the question becomes, can or can't you drive the carpaint flake values via external float nodes?


cheers,


rob

[Buck]

I believe there's already a known bug where OSL shader (flakes) parameters don't work as expected when driven by another input node in newer versions of v-ray. Possibly this is related?

[Rork]

Possibly, yes..

But then it can be a long standing bug, as for this project we're relying on quite a early version of Vray.

Thanks for the reply, good to know I'm not completely mad

cheers,

rob

[Buck]

Possibly, yes..

But then it can be a long standing bug, as for this project we're relying on quite a early version of Vray.

Thanks for the reply, good to know I'm not completely mad

cheers,

rob

The issue I'm referring to (OSL shaders) was something that cropped up recently, I THINK. So this might be a different bug.

[yolov]

The flake density parameter expects a simple float input and will not sample a texture. If you're trying to use a floatConstant - (just guessing and testing) - it will not work for the same reason.
You can set it up in a different way and still be able to control everything from one place, though, here's a few options:
*) you can connect a vrayUserScalar.defaultValue to the carpaint inputs and a simple float value will be passed there;
*) you can use an expression that reads a custom attribute (for example on a dummy node or on part of a rig)

I'll make a note so we can see if we can make floatConstant work in this case, as this would be the most intuitive thing to use.

[yolov]

Scratch that - just looked into the export, it seems we only read the in_float attribute of the floatConstant texture.
By default, the outFloat attribute is connected (as it should be), so we'll have to fix that in our export.
In the meantime, on top of the workarounds suggested above, you can still use a floatConstant, but make sure to connect inFloat to flakeDensity!

[Rork]

Hi,

Thanks for the reply and looking into this.
It's good to see some workarounds showing up, even when the project is finished.

Never crossed my mind to use the vrayUserScalar node for this, but good to see I was (kind of) on the right track with the floatConstant node.
I'll make a mental note of this for the next time, but it would be great to see both options being available in a future update.

cheers!

rob