The Particle Sampler Info node can be used to provide additional particle shading control in mental ray shaders.
Although mental ray for Maya can render many types of particles (including hardware particles like Streak, Point, Sphere, and so forth) it is only able to use the Particle Sampler Info node with the following particle types.
The particle type can be set via the Particle Render Type attribute under the Render attributes section in the particleShapeAttribute Editor.
Only the following subset of attributes on the particleSamplerInfo node are available for use with mental ray shaders:
Follow this workflow to use the particleSamplerInfo node with a mental ray shader. This example creates a particle emitter where each particle has a random color and then uses a particleSamplerInfo node to supply the per particle color information to a mental ray shader.
In the Particle Color Editor window, select Add Per Particle Attribute and click Add Attribute. The RGB PP field now appears.