stensize(3G)							  stensize(3G)

NAME    [Toc]    [Back]

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

C SPECIFICATION    [Toc]    [Back]

     void stensize(long	planes)

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

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

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

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

SEE ALSO    [Toc]    [Back]

     drawmode, gconfig,	getgconfig, stencil, mssize

NOTES    [Toc]    [Back]

     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 stensize.

     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 stensize(0), as no stencil buffer planes	are
     required.

BUGS    [Toc]    [Back]

     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 lrectread.	 Use getgdesc to determine whether your
     machine has alpha bit planes.


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