backbuffer(3G)							backbuffer(3G)

NAME    [Toc]    [Back]

     backbuffer, frontbuffer - enable and disable drawing to the back or front
     buffer

C SPECIFICATION    [Toc]    [Back]

     void backbuffer(Boolean b)

     void frontbuffer(Boolean b)

PARAMETERS    [Toc]    [Back]

     b	  is either TRUE or FALSE.

	  TRUE enables updating	in the back/front bitplane buffer.

	  FALSE	disables updating in the back/front bitplane buffer.

DESCRIPTION    [Toc]    [Back]

     The GL supports four separate framebuffers:  pop-up, overlay, underlay,
     and normal.  Three	of these framebuffers, overlay,	underlay, and normal,
     can be configured in double buffer	mode.  When so configured, a
     framebuffer includes two color bitplane buffers:  one visible bitplane
     buffer, called the	front buffer, and one non-visible bitplane buffer,
     called the	back buffer.  The commands swapbuffers and mswapbuffers
     interchange the front and back buffer assignments.

     By	default, when a	framebuffer is configured in double buffer mode,
     drawing is	enabled	in the back buffer, and	disabled in the	front buffer.
     frontbuffer and backbuffer	enable and disable drawing into	the front and
     back buffers, allowing the	default	to be overriden.  It is	acceptable to
     enable neither front nor back, either front or back, or both front	and
     back simultaneously.  Note, for example, that z-buffer drawing continues
     to	update the z-buffer with depth values when neither the front buffer
     nor the back buffer is enabled for	drawing.

     frontbuffer and backbuffer	state is maintained separately for each	of the
     overlay, underlay,	and normal framebuffers.  Calls	to these routines
     affect the	framebuffer that is currently active, based on the current
     drawmode.

     backbuffer	is ignored when	the currently active framebuffer is in single
     buffer mode.  frontbuffer is also ignored when the	currently active
     framebuffer is in single buffer mode, unless zdraw	is enabled for that
     framebuffer (see zdraw).

     After each	call to	gconfig, backbuffer is enabled and frontbuffer is
     disabled.

SEE ALSO    [Toc]    [Back]

     drawmode, doublebuffer, getbuffer,	gconfig, singlebuffer, swapbuffers,
     zdraw, rightbuffer, leftbuffer





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backbuffer(3G)							backbuffer(3G)

NOTE    [Toc]    [Back]

     IRIS-4D G,	GT, and	GTX models, the	Personal Iris, Indigo Entry, Indy, XL,
     XS, XS24, XZ, Elan	and Extreme systems do not support double buffer
     operation in the overlay and underlay framebuffers.  IRIS-4D
     RealityEngine model does not support double buffer	operation in the
     underlay framebuffer.

     At	most four color	buffers, such as front-left, front-right, back-left,
     back-right, and zdraw, can	be rendered into simultaneously	on the IRIS-4D
     RealityEngine model.


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