sphbgnbitmap(3G)sphbgnbitmap(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.
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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
libsphere, sphdraw, sphcolor, acbuf, blendfunction, feedback, fogvertex,
logicop, lmdef, mssize, pick, RGBmode, stencil, texdef, writemask, zbsize
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