sphbgnbitmap(3G)					      sphbgnbitmap(3G)

NAME    [Toc]    [Back]

     sphbgnbitmap, sphendbitmap	- delimit specification	of bitmapped spheres

C SPECIFICATION    [Toc]    [Back]

     #include <gl/sphere.h>

     void sphbgnbitmap(void)

     void sphendbitmap(void)

PARAMETERS    [Toc]    [Back]

     none

DESCRIPTION    [Toc]    [Back]

     Spheres specified with sphdraw after sphbgnbitmap and before sphendbitmap
     are drawn with bitmapped spheres.	The bitmap contains an image of	a
     phong-shaded sphere.  The diffuse color of	the sphere may be specified by
     sphcolor.

     Between sphbgnbitmap and sphendbitmap, only calls to sphcolor and sphdraw
     are permitted and including any GL	calls or other Sphere Library calls
     will produce undefined results.

NOTE    [Toc]    [Back]

     Bitmapped spheres are currently only implemented on the RealityEngine,
     and with several restrictions.

     The framebuffer must be configured	for RGBmode with the standard buffer,
     ie.  the zbuffer must not be deallocated with zbsize. Multisample buffers
     must not be allocated. The	projection matrix for bitmapped	spheres	must
     be	orthographic and use of	perspective, such as calls to perspective or
     window will produce undefined results.

     The following operations are not obeyed when drawing bitmap spheres:
     accumulation buffering, blending, feedback, fog, lighting,	logicop,
     picking, stencil, texturing, and writemask.

     The values	for blendfunction and logicop are reset	to their default
     values.  If writemasking was being	used previous to drawing bitmapped
     spheres, the resulting writemask after sphendbitmap, will be undefined.
     Therefore,	it is best too ensure that blendfuction, logicop, and
     writemask modes are not being used	when entering the bitmap sphere	mode
     to	avoid surprises.

     On	RealityEngine, bitmapped spheres compete for framebuffer memory	with
     stereobuffer and at least a medium	pixel depth is required	to have	room
     for both.








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sphbgnbitmap(3G)					      sphbgnbitmap(3G)



BUGS
     Bitmapped spheres on RealityEngine	are currently only available in
     immediate mode.

     Bitmapped spheres do not clip correctly but pop when clipped against the
     near and far clipping planes. User-defined	clipping planes	are ignored by
     the bitmapped spheres.

     Currently,	on RealityEngine, sphbgnbitmap is relatively slow to execute
     and so it is best to minimize the number of times the bitmap sphere mode
     is	entered	in a frame.  Draw as many spheres as possible between one set
     of	sphbgnbitmap and sphendbitmap calls.

SEE ALSO    [Toc]    [Back]

     libsphere,	sphdraw, sphcolor, acbuf, blendfunction, feedback, fogvertex,
     logicop, lmdef, mssize, pick, RGBmode, stencil, texdef, writemask,	zbsize


									PPPPaaaaggggeeee 2222