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RenderMan supports up to 4 diffuse lobes and are named via the following options.
Specular and Glossy Lobes
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Bxdfs can emit light by overriding the RixBxdf::EmitLocal() method. This local light emission is not considered by the lighting services and is therefore not importance sampled. Local light emission is intended for low intensity emission. If this emission significantly contributes to the lighting of the scene, a proper light source should be used for performance reasons (less noisy images).
Lobe Names
Bxdf lobes are typically retrieved by name using the RixBXLookupLobeByName routine. The names correspond to options set by the user or bridge. The first lobe of each type (diffuse, specular, user) is used as a catch all if node lookup fails. The following lists commonly declared lobe names:
| Lobe/Option | Common Values |
|---|---|
lpe:diffuse2 | Diffuse,HairDiffuse |
lpe:diffuse3 | Subsurface |
lpe:specular2 | Specular,HairSpecularR |
lpe:specular3 | RoughSpecular,HairSpecularTRT |
lpe:specular4 | Clearcoat |
lpe:specular5 | Iridescence |
lpe:specular6 | Fuzz,HairSpecularGLINTS |
lpe:specular7 | SingleScatter,HairSpecularTT |
lpe:specular8 | Glass |
lpe:user2 | Albedo,DiffuseAlbedo,SubsurfaceAlbedo,HairAlbedo |