The V-Ray Hair Sampler is a utility node that provides extra output attributes that can be used when shading hair.

This texture allows you to map color, incandescence, and transparency along the length of a hair strand, as well as the ability to randomize such properties on a per-strand basis to create stunning hair looks.

UI Path: ||Node Editor|| > Shader > Add > Texture Utilities > V-Ray Hair Sampler

The Hair Sampler node contains these unique input and outputs:

Distance Along Strand – Provides information about the shaded part of the hair strand. For the base of the strand, the value is 0.0, and for the tip, it is 1.0.

Distance Along Strand Absolute – Provides information about the shaded part of the hair strand using absolute distance. This option uses the Hair Max Distance parameter to allow length-dependent mapping. For instance, when used with a gradient, this allows for all hair strands (regardless of length) to have a root color all up to the same length, followed by the rest of the ramp. Note that when Hair Max Distance is lower than the actual length of the hair strand, the gradient is repeated over the length of the hair strand.

Position Across Strand – Allows textures to be mapped across each strand.

Random By Strand – Provides a unique random floating point value for each strand in the hair system, which can be used with a ramp texture, for example, to blend between two colors.

Hair Max Distance – Sets the max strand length. Typically, this value should be equal to the longest strand of hair.