I’m trying to make a general purpose iridescence material that could be used for anything that requires a bit of glow, like paint or jewelry or coral or soap bubbles or whatever.
Iridescence is caused by wave interference between a surface and its under-surface (substrate). The angle of view shifts the hue of the surface color. It’s a form of sub-surface scattering, but it’s the thin-filmed kind that Blender does not support. Besides, SSS is expensive, and this is pretty darn fast.
Anyhoo, here’s a short vid of my tests so far, and a .blend file. Please excuse the blobby models :rolleyes:.
Blend file (includes 3 scenes, so check that):
irid_tests.blend (178 KB)
Basically I hue shifted according to the surface normal’s direction away from the camera. The rest is tweak.
To tweak it yourself, start with the “Power” node, which will adjust the falloff. Then fiddle with the next “Multiply” math node, which will determine the range of the hue shift. Then play with the color in the Hue/Saturation node. You can also set the base color of your material in the normal way, as well as the specularity, etc.
I have a lot of “tweak points” in the node setup since I’m testing. Anything with a type-in value is fair game.