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GL3.2 for AIX: Graphics Library (GL) Technical Reference
zfunction Subroutine
Purpose
Specifies the function used for depth comparison.
Libraries
Graphics Library
C (libgl.a)
FORTRAN (libfgl.a)
C Syntax
void zfunction(Int32 func)
FORTRAN Syntax
SUBROUTINE ZFUNCT(func)
INTEGER*4 func
Description
The zfunction subroutine compares the z value of the current contents (destination value) of a pixel against the z value for the contents that you want to write to that pixel (source, or incoming, value).
For example, if the func parameter is ZF_LESS and if the source z is less than the destination z, the system overwrites the destination pixel value with the source pixel value.
Note: The operation of this subroutine for the Supergraphics Processor Subsystem is modified.
(See "Hardware Considerations".)
Parameter
func |
Expects one of eight possible flags used when comparing z values. The available flags are:
C |
FORTRAN |
Description |
ZF_NEVER |
ZFNEVE |
Never overwrite the destination pixel value. |
ZF_LESS |
ZFLESS |
Overwrite the destination pixel value if the z of the source pixel value is less than the z of destination value. |
ZF_EQUAL |
ZFEQUA |
Overwrite the destination pixel value if the z of the source pixel value is equal to the z of destination value. |
ZF_LEQUAL |
ZFLEQU |
Overwrite the destination pixel value if the z of the source pixel value is less than or equal to the z of destination value. (This is the default value.) |
ZF_GREATER |
ZFGREA |
Overwrite the destination pixel value if the z of the source pixel value is greater than the z of destination value. |
ZF_NOTEQUAL |
ZFNOTE |
Overwrite the destination pixel value if the z of the source pixel value is not equal to the z of destination value. |
ZF_GEQUAL |
ZFGEQU |
Overwrite the destination pixel value if the z of the source pixel value is greater than or equal to the z of destination value. |
ZF_ALWAYS |
ZFALWA |
Always overwrite the destination pixel value. |
|
Implementation Specifics
This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.
Files
/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
Clearing the color bitplanes and the z-buffer simultaneously with the czclear subroutine.
Initiating z-buffer mode with the zbuffer subroutine.
Selecting depth or color as the source for z comparisons with the zsource subroutine.
AIX Graphics Library Overview,
Writemasks and Logical Operations, and Removing
Hidden Surfaces.
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