set_dither Subroutine

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

set_dither Subroutine

Purpose

Controls the dithering of polygons and blits.

Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void set_dither (Int32 mode)

FORTRAN Syntax

SUBROUTINE SETDITHER (mode)
INTEGER*4 mode

Description

The set_dither subroutine controls whether dithering is applied to blits and polygons. Dithering is a type of rounding or truncating of 24-bit pixel color values to make them fit in a smaller (typically 8-bit) frame buffer. Dithering avoids the sharp changes in color (Mach banding) that normally occur when all pixel color values are truncated in the same way. Dithering helps maintain the impression of smooth shading in small frame buffers.

Note: To enable dithering of both polygons and blits, call set_dither with the bitwise-OR of both the DITHER_POLYGONS and DITHER_BLITS flags. Calling set_dither with just one of these two flags will automatically disable the other mode.

Parameters

mode	Token representing the type of dithering to be enabled.
	DITHER_OFF (Dithering is disabled for both polygons and blits.)
	DITHER_POLYGONS (Dithering is enabled for polygons and triangles.)
	DITHER_BLITS (Dithering is enabled for blits.)

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

AIX Graphics Library Overview and Using the Keyboard.