The Diffuse tab is part of the VRay Material parameters.
Diffuse
Color – The diffuse color of the material. Note that the actual diffuse color of the surface also depends on the reflection and refraction colors.
Texture – Specifies a texture file to be used for the diffuse color slot.
Mix Strength – Specifies a blend amount for the texture map.
Diffuse Roughness – Used to simulate rough surfaces or surfaces covered with dust (for example, skin, or the surface of the Moon). See the Diffuse Roughness example for more information. A map can be attached to this slot.
Example: Diffuse Roughness
This example demonstrates the effect of the Roughness parameter. Note how, as the Roughness increases, the material appears more "flat" and dusty.
Roughness = 0.0
Roughness = 0.1
Roughness = 0.2
Roughness = 0.3
Roughness = 0.4
Roughness = 0.5
Roughness = 0.6
Roughness = 0.7
Roughness = 0.8
Roughness = 0.9
Roughness = 1.0
Opacity
Source – Specifies the source of the opacity for the material.
Default – The RGB channel from the currently attached texture is used for opacity. This is the default behavior.
Alpha from Texture – The alpha channel of the currently attached texture is used for opacity.
Alpha from Diffuse – The alpha channel of the texture attached in the Diffuse channel is used as opacity. This option saves additional steps when setting up materials: you can use the Diffuse channel to attach bitmaps with embedded alpha channel for both Diffuse and Opacity. It eliminates the need to use and add the same bitmap in the Opacity channel.
Color — Controls the transparency of the material where white is opaque, and black is fully transparent.
Texture – Specifies a texture file to be used for the opacity.
Mix Strength – Specifies a blend amount between the texture map and the color.
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Self-Illumination
Color – The self-illumination color of the material.
Texture – Specifies a texture file to be used for the color of the self-illumination.
Mix Strength – Specifies a blend amount between the texture map and the color.
Self-Illumination Affects GI – When enabled, the self-illumination affects global illumination rays and allows the surface to cast light on nearby objects. Note, however, that it may be more efficient to use area lights or VRayLightMtl material for this effect.
Compensate Camera Exposure – When enabled, the intensity of the Self-Illumination is adjusted to compensate the exposure correction from the VRayPhysicalCamera.
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