Create and edit the “color set” component of materials.
Each of the asset bars have a common group at the top. View this page to read about the common asset groups.
A color set can be thought of as everything associated with a material besides the texture maps. Color sets are separated from the actual materials because this makes it easier to combine materials for faster rendering in the SpeedTree Compiler and SDK. This is because if two materials are composited into a texture atlas and have all the same color values (which are uploaded to the graphics card), then they can be rendered at the same time.
The 'Diffuse' color is the color due to lighting, while Ambient is the color present everywhere in the environment. The Ambient color can be locked to the 'Diffuse' color. The “Light scalar” can increase or decrease the overall brightness in the directional lighting.
“Contrast” darkens the transitional area between the diffuse color and the ambient color. The result is similar to light bouncing off of the ground, giving the tree a slightly “backlit” look.
'Specular' lighting is light that bounces off a surface and reflects into the observer's eye. 'Specular' lighting can be disabled with the checkbox. The color controls the appearance of the specular highlights. The glossiness of it controlled by “Shininess.”
'Transmission' is the passage of light through a medium. 'Transmission' is used on leaves and fronds to approximate light scattering and brightening of the backsides of the leaves.
To disable the effect entirely, use the checkbox.
The 'Transmission' color controls this effect. A color of (0.33, 0.33, 0.33) means no transmission, while higher values get added to the back sides. Values lower than (0.33, 0.33, 0.33) should be avoided since they can actually make the back sides darker.
“View influence” controls the dependence on the viewer's direction – “0.0” means transmission always occurs, while “1.0” means transmission only occurs when the viewer is looking directly at the light through the object.
“Shadow offset” allows for the brightening of shadows where transmission occurs.
The “Alpha scalar” is multiplied by the final alpha (Diffuse color + Diffuse texture), making for a less transparent texture. This is useful when using alpha to coverage (A2C) transparency method. “Cull faces” controls whether the material will be backface culled, frontface culled, or two-sided (None). Generally, color sets assigned to branch geometry (and some mesh fronds) are the only cases where you will need to backface cull.