This shader is deprecated and should only be used with the Standard shader.

This shader can be used to render materials with complex index of refractions. The Standard shader can compute the Fresnel effect for dielectric materials like plastic and glass based on the refractive index of the material; however, metals have a more complicated Fresnel reflective curve that also depends on another parameter called extinction coefficient.

You should not use the Complex IOR shader with the Standard Surface shader. The Standard Surface has the complex Fresnel built-in when the metalness is > 0, using the base and specular color.


'Complex IOR' shader connected to 'Specular Color' of Standard shader (Specular Fresnel disabled).





Presets of different materials. The custom mode allows you to define a custom setting. By clicking on the Edit button, the selected preset overrides the Reflectivity, Edgetint, and n, k fields, allowing you to refine the settings.

Custom preset

You are able to save and load your custom presets in the custom material mode. The Custom preset combo box lists all saved presets. Clicking on Save will override the current custom preset, clicking on Save as... allows you to save the preset with a new name.

Presets are not saved to the scene they stored on the local machine in the C4D user folder, which is $HOME/Preferences/MAXON/CINEMA 4D R[version]/'C4DtoA/presets/complex_ior on OSX and %HOME%\AppData\Roaming\MAXON\CINEMA 4D R[version]\C4DtoA\presets\complex_ior on Windows.


Select between the artist friendly (Reflectivity and Edgetint colors) and physical (n and k) controls.

Reflectivity: blue. Edgetint: purple.


The reflectance at normal incidence.


Controls the color bias as the viewing direction becomes parallel to the surface.


The refractive index value for the red/green/blue wavelengths (e.g. 0.65, 0.55 and 0.45 micrometers).


The extinction coefficient value for the red/green/blue wavelengths (e.g. 0.65, 0.55 and 0.45 micrometers).

The site has measured n and k values for many materials like copper, gold, etc.

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