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I have been wondering how to create a diffraction grating material with cycles.

From the Wikipedia article:

In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element.

Diffraction is what creates the colors on a compact disc. I am interested mainly in reflective rather than transmissive diffraction, i.e. the light is diffracted on a bounce rather than as it passes through a material. I have heard that cycles currently does not support true diffraction (though most of what I have read is from a while ago). So I would be equally interested in some kind of node trick to achieve the effect if this is still not so.

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  • $\begingroup$ Related: blender.stackexchange.com/q/1605/599. AFAIK this cannot be simulated in cycles accurately yet, but it can be convincingly faked in many ways. $\endgroup$ – gandalf3 Sep 17 '14 at 20:51
  • $\begingroup$ @gandalf3 thanks a lot! A convincing fake sounds good to me, so if you could explain a couple of those many ways as an answer it would be nice :). As for the linked question, the first answer is almost what I am looking for. I am thinking of something that is mostly plain glossy but at certain angles reflects only certain wavelengths (i.e. colors). I will see if I can get a picture, so far my camera is not doing such a great job. $\endgroup$ – PGmath Sep 17 '14 at 22:42
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You could try a setup like this:

enter image description here

enter image description here

It's probably not physically accurate at all, but with a bit of work you can make a pretty decent looking effect.

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