Iridescence Shader

[Macha]

I'm trying to make a iridescence shader.

The basic color pattern works but there are still problems with it. For example, the shader behaves differently with different lights. Not sure yet if that is a bug or correct behavior. There are also antialias issues.

Here is a viewport animation:

and here a rendered one:

The 2 pictures below show a dark line that appears when adding 2 lights. This line is also apparent in a standard shader, but much weaker. A bug or not, I don't know yet, but it would be nice to be able to control it.

The third image shows the behavior with an environment light (and slightly different settings). I suppose the shader requires a light with strong directionality, otherwise the light samples average the effect.

The forth image shows how I went about to design the shader. Green are camera direction vectors, yellow for light, and red represents the final effect.

Fifth is a render.

Edited March 15, 2010 by Macha

[Macha]

and a screenshot

Edited March 15, 2010 by Macha

[symek]

Just for a record, if you by chance haven't seen this: http://forums.odforc...l__Iridescence. I use that code a lot in deadly need of rainbow...

Edited March 15, 2010 by SYmek

[mightcouldb1]

I like it!

[Macha]

Just for a record, if you by chance haven't seen this: http://forums.odforc...l__Iridescence. I use that code a lot in deadly need of rainbow...

Thanks, aah, but this is more of a learning-project, to see what's under the hood.

What I am looking for though is iridescent refraction. That's what I am ultimately hoping to achieve. I know I can fake it by combining a few refractions with differing refractive index for different colors. But such a discrete approach doesn't give a very good result and involves adding expensive nodes. Instead, a continuous approach would be needed but I haven't found any good references for such things yet.

[eetu]

What I am looking for though is iridescent refraction. That's what I am ultimately hoping to achieve. I know I can fake it by combining a few refractions with differing refractive index for different colors. But such a discrete approach doesn't give a very good result and involves adding expensive nodes. Instead, a continuous approach would be needed but I haven't found any good references for such things yet.

Enter Mario and his glass shader odyssey.

Also his Implementing Spectral Colors in Mantra masterclass should be relevant.

eetu.