It allows you to quickly map a texture without using a UV map, by projecting it from all six sides.
Input
This is where you connect an image or another texture node.
Coord Space
Specifies the coordinate space to use. These include World, Object, and Pref coordinates. Pref is short for 'vertex in reference pose'. The plugin can pass these vertices to Arnold (in addition to the regular, deformed vertices) which can, in turn, be queried by the noise shader so that the noise 'sticks' to the reference pose and does not swim as the mesh deforms.
Pref Name
Specify the name of the reference position user-data array. Previously, the name was hard-coded as "Pref", which is still the default.
Blend
Blends together the projected textures from each side smoothly.
Transform
Scale
Scales the image.
Rotate
Controls how much the texture is rotated within the texture frame.
Offset
Controls how much the texture is rotated within the texture frame.
Cell
Rotate
Controls rotation of the randomization.
Blend
Controls the blending width.
Example use of Triplanar in a shading network