NAME

zbuffer − starts or ends z-buffer operation

SPECIFICATION

C
zbuffer(bool)
Boolean bool;

FORTRAN
subroutine zbuffe(bool)
logical bool

Pascal
procedure zbuffer(bool: longint);

DESCRIPTION

zbuffer starts (bool = TRUE) or ends (bool = FALSE) z-buffer mode.  In z-buffer mode, each pixel has an associated z value.  To draw a pixel, the system compares the new z value with the z value already associated with it.  If the new z value is less than or equal to the existing value (i.e., closer to the viewer), then a new color and z value are stored in the bitplanes; otherwise, the color and z value for the pixel are left unchanged. 

All obscured surfaces in objects drawn in this mode are not displayed.  z values range from 0xC000 to 0x3FFF on a 32-bitplane system, and 0x0 to 0xFFF on a 28-bitplane system.  setdepth sets this range. 

z-buffering is not effective on systems with less than 28 bitplanes.  Because memory bandwidth is reduced on 60Hz monitors, you can improve performance by blanking the screen during z-buffer drawing with blankscreen . 

SEE ALSO

getzbuffer, zclear, setdepth, blankscreen IRIS Graphics Programming, Section 12.1, Z-Buffer Mode

Version 2.5r1  —  October 29, 1986