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GL3.2 for AIX: Graphics Library (GL) Technical Reference

wmpack Subroutine


Specifies RGBA writemask with a single packed integer.


Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void wmpack(Uint32 pack)


INTEGER*4 pack


The wmpack subroutine changes the current RGBA writemask. Bytes 0, 1, 2, and 3 are alpha, blue, green, and red, respectively (red is the least significant byte in the packed integer, then green, blue, and alpha). Components must range from 0 through 255.

For example,


sets red mask to 0x80, green mask to 0x40, blue mask to 0, and alpha mask to 0xFF.

Note: You can load alpha values only if the graphics adapter has alpha bitplanes.

You can also use the wmpack subroutine in color map mode to specify writemasks of more than 12 bits. This is useful for certain z-buffer and smoothline applications.


pack Specifies a packed integer containing the RGBA writemask.

Implementation Specifics

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

The POWER GXT1000 adapter supports only on/off control of individual R, G, and B bitplanes. Individual bits cannot be masked in the color planes.


/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

Returning the current writemask with the getwritemask subroutine.

Returning the current RGB writemask with the gRGBmask subroutine.

Granting write access to a subset of available bitplanes with the RGBwritemask subroutine.

Granting write permission to a subset of available bitplanes with the writemask subroutine.

Configuring the Frame Buffer, Removing Hidden Surfaces, and Smoothing Jagged Lines with Antialiasing.

Writemasks and Logical Operations and Working in Color Map and RGB Modes.

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