sphbit(3G)

NAME
     sphbbp, sphebp - delimit specification of bitmapped spheres

FORTRAN 77 SPECIFICATION
     #include <gl/fsphere.h>

     subroutine sphbbp()

     subroutine sphebp()

PARAMETERS
     none

DESCRIPTION
     Spheres specified with sphdra after sphbbp and before sphebp 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 sphclr.

     Between sphbbp and sphebp, only calls to sphclr and sphdra 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 perspe 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 sphebp, 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, sphbbp 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
     sphbbp and sphebp calls.

SEE ALSO
     libsphere, sphdra, sphclr, acbuf, blendf, feedba, fogver, logico, lmdef,
     mssize, pick, RGBmod, stenci, texdef, writem, zbsize