Arnold for 3Ds Max - Render to texture - Light refraction

Waz0

Hello everyone,

I'm looking for a solution to bake light refraction in 3ds max using Arnold renderer. I have two objects using the Arnold's standard surface material, one with emission to 1, and another one set to glass following some tuts, that is sopposed to receive the light from emission.

As far as I know, the result of light refraction rely on camera position so trying to bake it seem contradictory, but is there some way to fake it like some people fake the baking of matcaps for example ? I aim for a result like below or approaching (the light effects on the upper part where the rays get caugth by extreme angles).

Thanks !

Eric Chadwick

No unfortunately it won't brighten up the edges.

That's a view-dependent effect like you said, but in RTT the view angle is orthagonal along the W axis in UV space. In other words, straight out from the surface, at every point. 

So, the baked texture will look like the middle part of the glass there.

The way to replicate this in a game engine is to add a Fresnel or rim lighting pass in your shader, and crank it up really strong.

Waz0

Hey, thanks for the quick answer. I was hopping for some magic trick but not really surprised by this outcome. Like you said I'd rather do something within the shader itself but can't, so that's why I try to fake it.

Those infos on rtt behaviour are interesting though.
I'll post back if I manage to find a rendering technique approaching the photo ref visual. Thanks again

Eric Chadwick

I'm in the same boat, I want view dependent fx to work with a fixed-shader system. Velvet and satin in my case, in glTF.

Good luck, let me know how it goes.

poopipe

Not really related to the OP but Eric you might have some success feeding the Shader a fixed vector rather than camera position etc. And then rendering to texture.

Failing that you can do the same sort of thing in substance designer if you're willing to dig into the pixel processor a bit

Eric Chadwick

Thanks! Doesn't really work for rim-lighting kinds of fx, leaves a bright band around the model. What we really need is programmable shaders for the real-time renderer. Gotta keep advocating!