stensi(3G)

NAME
     stensi - specify the number of bit planes desired to comprise the stencil
     buffer

FORTRAN SPECIFICATION
     subroutine stensi(planes)
     integer*4 planes

PARAMETERS
     planes   is the number of bit planes requested to be configured as
              stencil planes.  Only values 0 through 8 are accepted.  The
              default is 0.

DESCRIPTION
     stensi specifies how many bit planes are requested to be configured as
     stencil planes.  The constraints on planes are machine dependent.  Call
     getgde(GDBIST) to determine the maximum number of bit planes available
     for stencil operation.

     stensi takes effect only after gconfi has been called.  The number of bit
     planes granted for the stencil buffer may not be exactly what was
     requested.  Call getgco(GCSTEN) to determine how many bit planes were
     configured as stencil buffer planes.

     Because stencil bit planes are available only in the normal framebuffer,
     stensi should be called only while draw mode is NORMAL.

SEE ALSO
     drawmo, gconfi, getgco, stenci, mssize

NOTES
     This routine is available only in immediate mode.

     IRIS-4D B, G, GT, and GTX models, as well as the Personal Iris, Indy,
     Iris Indigo Entry, and XL, do not support stensi.

     XS, XS24, XZ, Elan and Extreme systems support up to 4 stencil planes,
     which are borrowed from the Z buffer. The resolution of the Z buffer
     decreases when using stencil planes on Elan systems.

     On the IRIS-4D RealityEngine models the stencil buffer and the stencil
     component in the multisample buffer are independent.  When the
     multisample buffer is requested in the current framebuffer configuration,
     it is recommended to call stensi(0), as no stencil buffer planes are
     required.

BUGS
     IRIS-4D VGX machines without the optional alpha bit planes allocate
     stencil bit planes from the least-significant Z buffer bit planes.  Z
     buffer operation compensates for this allocation automatically, so the
     programmer is aware of the allocation only when the Z buffer contents are
     read back using lrectr.  Use getgde to determine whether your machine has
     alpha bit planes.