How To Achieve a Dichroic Film Iridescent Effect

[joelly3d]

I have never seen an effect like this rendered before but it looks like this guy did it in Octane. ANy idea how to even achieve this in VRay? I have a request to make a backpack out of this material.


Example:
https://vimeo.com/147734991
and another here:
https://vimeo.com/323043623

Thanks in advance for any insights!

[^Lele^]

I'd suggest using the thin film shader found here, and some map to drive change between min and max thickness (which will provide for some more random color variations.).
If you pipe the map into the refraction channel, ensure you also let it use reflColor as alpha output, or it'll come out black.(You'll know when you'll get there).
Alternatively, you can pipe it into the fog color (with the alpha mapped as well).

[fixeighted]

A very quick play with this.
Based on some random tweaks to the shader here...https://docs.chaosgroup.com/display/...in+Film+Shader

EDIT: LeLle beat me to it

[joelly3d]

Interesting, I've never even noticed that shader in there.. haha! Thanks for the tips guys!

[squintnic]

i used it here and it was just ok - albeit hard to control, hard to preview and definitely not user friendly

[^Lele^]

It was never meant to be used creatively, but rather to mimic known films by their thickness and IoRs.
How would it have to change to become more user friendly, you'd say?

[dgruwier]

Here's a resource that might be helpful in understanding what's going on and help predict what you're getting out of the shader. Also I think this shader is actually built into Vray in the plugin textures, at least it has been in the Maya nightlies for a long while now.

A preview of the color gradient created between the min and max thickness values would make it a lot more artist friendly. That or viewport support.
That being said, at that point you should probably just use a fresnel/falloff to drive a regular gradient ramp, that's how I always do it. I don't see the point of using the thin film shader for the inconvenience of having to guess instead of just picking the colors I want.

[^Lele^]

Here's a resource that might be helpful in understanding what's going on and help predict what you're getting out of the shader. Also I think this shader is actually built into Vray in the plugin textures, at least it has been in the Maya nightlies for a long while now.

A preview of the color gradient created between the min and max thickness values would make it a lot more artist friendly. That or viewport support.
That being said, at that point you should probably just use a fresnel/falloff to drive a regular gradient ramp, that's how I always do it. I don't see the point of using the thin film shader for the inconvenience of having to guess instead of just picking the colors I want.

I think i agree with the analysis. Knowing the gradient without knowing the normals and view direction may prove too little, while if one was to be too explicit in driving the behaviour, one may as well resort to simpler approaches.
I'd think IPR would be the most helpful (it was for my simple setup above), these days.

also, yeah, i totally forgot to use the pluginNode. Old dog, new tricks, and all that. XD

[dgruwier]

also, yeah, i totally forgot to use the pluginNode. Old dog, new tricks, and all that. XD

To be fair the documentation doesn't even mention it which is why I wasn't entirely sure if it was only in the nightlies still. The Complex Fresnel Shader page has a helpful reminder that its functionality is now native in Vray.

[joelly3d]

I appreciate the notes everyone! I'll post my results when completed. Such a great community!

[PIXELBOX_SRO]

https://www.sigershop.eu/free-3ds-ma...maps-thinfilm/

this here is by far the best implementation.

[fixeighted]

Good find, thanks

[^Lele^]

Nice idea that of the addition of CC controls.
I wonder if it'd work on our side nesting the OSL map into a CC one...

edit: ahah, he copy/pasted our whole help section. ^^

[^Lele^]

The plugin texture is even more advanced than the third party one, look here:


Further, it works no problem as child of a CC map, so more tweaking can be done to suit one's needs.

[joelly3d]

Siger Studio has created a plugin that achieves this also.
https://www.sigerstudio.eu/sigertexmaps-thinfilm/