NAME

zbuffer - starts or ends z-buffer operation

SPECIFICATION

C
zbuffer(bool)
Boolean bool;

FORTRAN
subroutine zbuffe(bool)
logical bool

Pascal
procedure zbuffer(bool: Boolean);

DESCRIPTION

zbuffer starts (bool = TRUE) or ends (bool = FALSE) z-buffer mode.  In z-buffer mode, each pixel has an associated z value.  When a pixel is to be drawn, a new z value is compared with the z value already associated with the pixel.  If the new z value is less than or equal to the existing one (i.e., closer to the viewer), then a new color and z value for the pixel are stored in the bitplanes; otherwise the color and z value for the pixel are left unchanged.  The result of drawing objects in this mode is an image in which all obscured surfaces are left undisplayed.  z values range from 0x8000 to 0x7FFF on a 32-bitplane system, and 0x0 to 0xFFF on a 28-bitplane system.  This range is set using the setdepth command.  z-buffering is not effective on systems with less than 28 bitplanes.  Because memory bandwidth is reduced on 60hz monitors, performance is improved by blanking the screen during z-buffer drawing with the blankscreen command. 

SEE ALSO

getzbuffer, zclear, setdepth, blankscreen

Version 2.3  —  July 04, 1985