[ Previous | Next | Contents | Glossary | Home | Search ]
GL3.2 for AIX: Graphics Library (GL) Technical Reference

zsource Subroutine


Selects either depth or color as the source for z comparisons.


Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void zsource(Int32 source)


INTEGER*4 source


The zsource subroutine selects either depth or color as the source for z comparisons . After a call to the gbegin, ginit, greset, or winopen subroutine, the default z-buffering is done with depth (z) values. In certain cases, it is desirable to buffer with respect to color values, especially the color index values generated by the smoothline hardware.

When the source parameter is ZSRC_DEPTH, the z-buffer operation is normal. When the source parameter is ZSRC_COLOR, however, source and destination color values are compared to determine which pixels the system draws.

  1. The Supergraphics Processor and the POWER GXT1000 adapter support only the ZSRC_DEPTH setting. The ZSRC_COLOR setting has no effect and is ignored.
  2. This subroutine is not supported on the POWER Gt4 and POWER Gt4x adapters. On these adapters, the function provided by this subroutine is superseded by the LO_MIN and LO_MAX values of the logicops subroutine.
  3. The POWERgraphics GXT1000 does not support the zsource subroutine.

The Z-Source Diagram shows the implementation of the z-source function.


source Specifies one of two possible flags:
C FORTRAN Description
ZSRC_COLOR ZSRCCO Buffering done by color value.
ZSRC_DEPTH ZSRCDE Buffering done by z value.

Implementation Specifics

This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.


/usr/include/gl/gl.h Contains C language constant and variable type definitions for GL.
/usr/include/gl/fgl.h Contains FORTRAN constant and variable type definitions for GL.

Related Information

Specifying logical, arithmetic, or comparison operations for pixel updates with the logicops subroutine.

Initiating z-buffer mode with the zbuffer subroutine.

Enabling or disabling drawing to the z-buffer with the zdraw subroutine.

Specifying the function used for depth comparison with the zfunction subroutine.

AIX Graphics Library Overview, Writemasks and Logical Operations, and Removing Hidden Surfaces.

[ Previous | Next | Contents | Glossary | Home | Search ]