Enables or disables the Stencil system for future draw operations.

While enabled, all pixels affected by draw operations will have their corresponding values in the active Render Target's Stencil Buffer compared against the current Reference Value and their current Depth Buffer value compared against the depth of the corresponding pixel from the draw operation.
Depending on the outcomes of these comparisons, one of either the Pass, Fail, or Z-Fail operations is performed on the pixel's Stencil Buffer value.
A pixel will only be updated in the active Render Target if the Pass Operation is performed.

For more detailed information on the Stencil system, including usage examples, see the Stencils Render Reference page