---
title: "Shader Properties"
url: "https://help.maxon.net/c4d/en-us/Content/html/XSLALUMAS-ID_SHADERPROPERTIES.html"
section_path: "Material Manager > Classic Materials > Classic material > Channel Shaders > Lumas Shader > Shader Properties"
element_id: "XSLALUMAS"
group_id: "ID_SHADERPROPERTIES"
description: "Here you can enable or disable the following settings. Disabled the option to use basic settings."
---

## Shader Properties

### Active

Parameter ID: `SLA_LUMAS_DIFFUSE_ACTIVE`

Here you can enable or disable the following settings. Disabled the option to use basic settings.

### Color

Parameter ID: `SLA_LUMAS_DIFFUSE_COLOR`

Sets the base diffuse color of the surface.

### Algorithm

Parameter ID: `SLA_LUMAS_DIFFUSE_ALGORITHM`

Specifies which illumination model Lumas will use. The drop-down list provides for two choices: Internal, which is the standard Lambertian model, and Oren Nayar, which provides for a roughness variable allowing the user to go from simple surfaces (0 Roughness, identical to Lambertian), to complex rough surface (1+ Roughness, which provides a matt surface, such as linen or dirt).

### Roughness

Parameter ID: `SLA_LUMAS_DIFFUSE_ROUGHNESS` · Range: [0..200%]

Dictates how rough the **Oren Nayar** illumination model will be. Zero is no roughness while 100% or greater is very rough. Experimentation is required to fully understand this parameter. This option is only available if **Oren Nayar** is selected in the Algorithm drop-down list.

### Illumination

Parameter ID: `SLA_LUMAS_DIFFUSE_ILLUMINATION` · Range: [0..1000%]

Scales the Color to produce attenuation in the illumination of the surface (this simply means it makes the color darker when the value is close to zero and brighter when the value is closer to 100% or above).

If you are using the Oren Nayar illumination algorithm, you may want to bump up the illumination by about 10% to 20% because it renders darker usually. Appropriate values are between 0% to 200%.

### Contrast

Parameter ID: `SLA_LUMAS_DIFFUSE_CONTRAST` · Range: [-1000..1000%]

Provides contrast for the result of the Color. Zero causes no effect, 0% - 100% causes standard contrast, above 100% causes a wrap contrast (the values that go above 100% wrap around to 0% again, used to create the Candy materials), negative values provide an inverse contrast that simulates materials that seem luminescent, such as silver. Appropriate values are -500% to 500%.