The Refraction shading model simulates how light bends and scatters as it passes through transparent or translucent materials. It allows you to create realistic glass, water, and similar surfaces by distorting light rays and tinting color based on depth. Use cases include:

• Transparent materials such as glass, ice, or water.
• Semi-translucent surfaces like frosted glass or thin plastic.
• Stylized effects requiring light distortion.

This shading model can use four texture inputs:

• Depth Map (Grayscale): Controls light absorption and tinting, simulating thickness. Thicker areas absorb or scatter more light.
• Scatter Map (RGB): Defines how light diffuses inside the material, creating effects such as translucency or soft internal glow.
• Mask Map (Grayscale): Determines which areas are refractive (white) versus opaque (black), allowing partial or selective refraction.
• Refractive Index Map (Grayscale): Specifies how much light bends when entering or exiting the surface. Higher values produce stronger refraction and reflection effects.

Setting	Description
Depth Map Texture Slot	Add a thickness texture by clicking on the slot or dragging and dropping one from the Library.
Use Albedo	The depth at which tint is realized due to absorption. Lower values mean more absorption and, thus, a darker and more opaque appearance. A value of zero disables absorption & scattering.
Depth Value (cm)	The depth at which tint is realized due to absorption. Lower values mean more absorption and, thus, a darker and more opaque appearance. A value of zero disables absorption & scattering.
Depth Color	A color tint for light passing through the object.
Scatter Map Texture Slot	Add a scatter texture by clicking on the slot or dragging and dropping one from the Library.
Scatter Value	Controls the amount of scattering of light passing through the object.
Scatter Color	Determines the scattering color of light passing through the object.
Scatter Anisotropy	DSpecifies the primary direction of scattering, either forward or backward. A value of zero is even, isotropic scattering.
Roughness Bias	Modifies refraction roughness. Positive values make refraction rougher than reflection, while negative values make refraction less rough.
Distortion Limit	Lower values limit the distortion effect in rasterized views, which is often useful for thin lenses. This setting does not affect ray traced renders.
Mask Map Texture Slot	Add a refraction mask texture by clicking on the slot or dragging and dropping one from the Library.
Channel Selection	Determines which channel of the texture map will be used. It’s useful when, instead of using multiple single textures, you use one texture with different grayscale maps in the different texture channels: Red, Green, Blue, and Alpha.
Mask	Sets the mask value that determines the strength of transmission. When a mask map is loaded, this value should be set to 1.
Invert	Inverts the mask value so that darker pixels correspond to stronger transmission.
Use Albedo Alpha	Uses the material’s albedo alpha value to provide a transmission mask.
Strict Normals	Use geometric normal to decide if a ray points towards the inside or outside of the mesh. Enabling this option might help with light leaks on low poly or poorly tessellated meshes. Applies only to ray tracing.
Derive Refractive Index from Reflectivity	Automatically derive index of refraction from Reflectivity. Uncheck this box to override with the index value above.
Refractive Index Texture Slot	Add a refraction index texture by clicking on the slot or dragging and dropping one from the Library.
Refractive Index Value	Sets the index of refraction. Higher values will distort light to a greater degree but won’t affect surface reflectivity.

Listed below are a number of refractive index values for reference:

Setting	Value
Vacuum	1.0000
Air	1.0003
Ice	1.309
Water	1.333
Ethyl Alcohol	1.361
Teflon	1.38
Fluorite	1.434
Glycerine	1.473
Benzene	1.501
Plexiglas	1.51
Crown Glass	1.52
Light Flint Glass	1.58
Polycarbonate Glass	1.59
Dense Flint Glass	1.66
Sapphire gemstone	1.77
Zircon	1.923
Diamond	2.417
Rutile	2.907
Gallium phosphide	3.50