Computes a thin-film interference effect on six spectral bands. @parameters
inputRGB: The color that will perturbed by interference effect.
eta: The index of refraction of the thin film. We assume the other the exterior medium is air.
spread: The index of refraction’s amount of variation across the color spectrum.
thickness: The thickness of the thin film in nanometers.
thicknessScale: Connect a pattern here to modulate the thickness. This will multiply the thickness value.
frontOnly: Compute only interference on front-facing points. By default, both sides are computed.