AlHair

Opacity – Assigns opacity to the material. White is completely opaque and black is completely transparent. 

Melanin – The melanin content of the hair fibre. Use this to generate natural colors for mammalian hair. 0 will give white hair, 0.2-04 blonde, 0.4-0.6 red, 0.6-0.8 brown and 0.8-1.0 black hair. If you want to set the color of the hair with a texture map, set this to 0 and use the Dye color parameter

Dye Color – Applies a color tint to the hair. For a dyed hair look, set the melanin to 0, otherwise, the melanin will darken the dye color and pheomelanin will introduce redness to it. White means no hair dye.

Diffuse Color – Controls the diffuse component of the shader. Use this for materials made out of cloth threads or other non-translucent fibers, as well as for dirty hair. Note that clean hair or fur does not normally have a diffuse component, so if you want to disable it, leave the diffuse amount at 0.

Diffuse Strength – Specifies the amount for the diffuse component of the material.

Forward Scattering – Controls the amount of light bleeding through the hair in dual-scattering mode.

Back Scattering – Controls the amount of light kicked back from the hair in dual-scattering mode.

Specular1 Color – Specifies the specular color component.

Specular1 Strength – Specifies the amount for the specular1 color component of the material.

Specular1 Shift – Offset on the shift of this lobe's highlight.

Specular1 Width Scale – Multiplier on the width of this lobe's highlight.

Specular2 Color – Specifies the color of the secondary specular component. If Lock to Transmission is enabled, this value is ignored, and the secondary specular color is derived from the transmission color.

Specular2 Strength – Specifies the amount for the specular2 color component of the material.

Specular2 Shift – Offset on the shift of this lobe's highlight.

Specular2 Width Scale –Multiplier on the width of this lobe's highlight.

Transmission Color – Specifies the color for the transmission component.

Transmission Strength – Specifies the amount of the transmission component.

Transmission Shift – Offset on the shift of this lobe's highlight.

Transmission Width Scale – Multiplier on the width of this lobe's highlight.

Random Melanin – Adds variation to the amount of melanin in each hair strand.

Random Hue – Adds variation to the hue component of the color. This makes each strand appear with a different color. This parameter has no effect, when color is not used, i.e. when the color is pure white.

Random Saturation – Randomizes the saturation of the color between hair strands. This makes each strand appear with a more or less saturated color. This parameter has no effect, when color is not used, i.e. when the color is pure white.

Random Tangent – Adds a random offset to the hair tangent. This makes the hair stands receive light from slightly different directions, which also means that the highlights will be placed in slightly different places for each strand. Note that this parameter is depends on the scene scale.

Diffuse Indirect Strength –

Glint Rolloff – Controls the rolloff of the caustic glints in the hair. Lower values make the glints more pingy, higher values make them softer and less apparent.

Glint Strength – Strength of the caustic glints. Sensible values are in the range 1-5.

Glossy Indirect Strength –

Specular Shift – Controls how much the highlights are shifted along the hair by the cuticles on the hair fibre. The recommended value for this parameter is the same or 50% higher than the value of the Specular Width parameter.

Specular Width – The width of the hair highlights, essentialy how shiny the hair appears. Values in the range 1-7 are sensible for human hair.

Transmission Rolloff – Controls the rolloff of the transmission highlight. Essentially, if you want the transmission highlight to only appear when the light is directly behind the hair, set this value to 10 or lower. If you want to increase the amount the highlight spreads as the light does not come directly from behind, set this value higher than 10.