sphbitmap(3G)

NAME
     sphbgnbitmap, sphendbitmap - delimit specification of bitmapped spheres

C SPECIFICATION
     #include <gl/sphere.h>

     void sphbgnbitmap(void)

     void sphendbitmap(void)

PARAMETERS
     none

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