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

readsource Subroutine

Purpose

Specifies the source for pixels to be read by various subroutines.

Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void readsource(Int32 source)

FORTRAN Syntax

SUBROUTINE READSO(source)
INTEGER*4 source

Description

The readsource subroutine specifies the exact pixel source (front buffer, back buffer, or z-buffer) that the rectcopy, readpixels, readRGB, and rectread subroutines use.

Note: This subroutine cannot be used to add to a display list.

Parameter

source The defined values for this parameter are listed in the following table:
Values for the source Parameter
C FORTRAN Function
SRC_AUTO SRCAUT Selects the front buffer in single buffer mode and the back buffer in double buffer mode.
SRC_FRONT SRCFRO Front color buffer. Valid for both single and double buffer operation.
SRC_BACK SRCBAC Back color buffer. Valid during double buffer operation only.
SRC_ZBUFFER SRCZBU Z-buffer. Valid during both single and double buffer operation.
SRC_OVER SRCOVE Overlay planes.
Note: The 3-D Color Graphics Processor does not support SRC_OVER.

Implementation Specifics

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

BLITs to and from the z-buffer are currently inoperational on the POWER GXT1000 adapter.

When performing BLITs to and from the overlay planes on the GXT1000, the transparent pixel value on the GXT1000 is 255, not 0.

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

Copying a rectangle of pixels with an optional zoom with the rectcopy subroutine.

Reading a rectangular array of pixels into host memory with the rectread subroutine.

AIX Graphics Library Overview, Reading and Writing Pixels, and Configuring the Frame Buffer.


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