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Labradorite Shader

Due to my passion for geology, I was inspired to try my hand at recreating the irridescence of labradorite(Labradorescence)

initial ideation:

The first thing I did was break down how the shader would even work in the first place. At first my initial idea was making multiple textures that blended together depending on the angle. during my research I came across the Fresnel effect

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Breakdown of the elements that could be involved in creating a labradorite shader:

Base Color Texture:

  • main texture representing the general color of the labradorite(in this case it was substituted with superficial cracks).

 

Irridation Effect:

  • This is the most crucial aspect, as labradorite displays iridescent colors that change with the viewing angle. Possible blending approaches:

    • Texture Blending: Blend between different color textures depending on the view angles

    • Fresnel Effect: The Fresnel effect shifts colours with the angle

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Normal Map:

  • Use a normal map to simulate the micro-structures and surface details of the labradorite.

 

Cracks and Inclusions:

  • Separate texture or procedural detail for cracks and inclusions:

 

Static Texture:

  • Use a static texture that doesn't change with the angle to represent cracks and other static imperfections.

 

Subsurface Scattering:

  • due to labradorite being mostly opaque no subsurface scattering would be necessary

 

Roughness Map:

  • Use a roughness map to control the micro-surface details, giving a more realistic look to the reflections and highlights.

 

Anisotropic Shading:

  • in some cases, anisotropic shading could be considered, however it is not necessary for this usecase.

Shader graph breakdown:​

First, the main colour and the iridescence colour are interpolated along with a Fresnel node. Interpolation is a method used to smoothly transition between two variables, in this case it is smoothly transitioning between the two colours with the frenel serving as the transition factor. The fresnel node itself simulates the behaviour of light on surfaces based on the angle of incidence. In unreal engine, fresnel can be  used in materials to create light effects which are stronger at glancing angles and weaker at perpendicular angles. since colour A is the base of the lerp and colour B is the secondary colour in the lerp, this means that if the person is looking at the shader's object perpendicularly, the shader is more blue and if the shader is looked at more diagonally it combines that blue with the gradient of orange and green. To combine this texture with cracking textures for added details and realism, I added a multiply node for a texture with smaller cracks which is then combined with one that has larger cracks using another multiply node

 

In terms of multiplying the same texture as the large cracks with the normal map, I did this in order to make the cracks more pronounced through the normal map due to the normal map not being made for this specific texture, rather it was one found online due to this simply being an experiment. As for the roughness, I simply used a normal constant number node connected to the roughness input. 

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Things to improve:​

- make an option which enables the person to choose the angle at which the labradorite shader is shown, as generally real labradorite tends to be unidirectional

- make the textures more pronounced and closer to real labradorite

- merge the colours with a different base colour for the freenell because real labradorite tends to have all the colours shine together with just the greyish blue as the base colour

- use stretched voronoi nose to create the labradorite cracking texture instead of a pre made texture

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