README.md

Multilayer-Thinfilm OSL Shader

Shader Toy

Many structures in nature have complex microstructures, some of which are composed of dozens to thousands of layers of alternating thin films (lamella). When light interacts with these structures a phenomena called interference produces dazzling colors that change depending on the viewing angle.

Illustration of the reflection and refraction of a multilayer material

Results

Nacre	Magpie Feather	Ammolite

Moonstone	Bottle Fly	Golden Stag Beetle

Film IOR

Index of refraction for the respective layer. Video below shows the impact of the IOR of the secondary layer.

Glossy	Glass
ior_gloss.mp4	ior_glass.mp4

Film Thickness

The film thickness specifies the mean thickness of the respective layer. Video below shows the impact of the mean thickness of the secondary layer.

Glossy	Glass
thickness_gloss.mp4	thickness_glass.mp4

Film Sigma

The film sigma specifies the variance of the layers thickness. The video below shows the impact of the variance of the secondary layer.

Glossy	Glass
sigma_gloss.mp4	sigma_glass.mp4

Lamella Normal

This parameter is useful when you want to mimic crystals such as labradorite and moonstone, which have their lamella structure oriented in a particular direction (plane of schiller).

Lamella_Normal.mp4

Sources:

• On the Origin of the Colour of Labradorite
• X-Ray Diffractoin in Crystals