Name

    EXT_abgr

Name Strings

    GL_EXT_abgr

Version

    $Date: 1996/03/20 12:39:33 $ $Revision: 1.1 $

Number

    

Dependencies

    None

Overview

    EXT_abgr extends the list of host-memory color formats.  Specifically,
    it provides a reverse-order alternative to image format RGBA.  The ABGR
    component order matches the cpack Iris GL format on big-endian machines.

New Procedures and Functions

    None

New Tokens
	
    Accepted by the < format > parameter of DrawPixels, GetTexImage,
    ReadPixels, TexImage1D, and TexImage2D:

	ABGR_EXT                     0x8000

Additions to Chapter 2 of the GL Specification (OpenGL Operation)

    None

Additions to Chapter 3 of the GL Specification (Rasterization)

    One entry is added to table 3.5 (DrawPixels and ReadPixels formats).
    The new table is:

									Target
	Name			Type		Elements		Buffer
	----			----		--------		------
	COLOR_INDEX		Index		Color Index		Color
	STENCIL_INDEX		Index		Stencil value		Stencil
	DEPTH_COMPONENT		Component	Depth value		Depth
	RED			Component	R			Color
	GREEN			Component	G			Color
	BLUE			Component	B			Color
	ALPHA			Component	A			Color
	RGB			Component	R, G, B			Color
	RGBA			Component	R, G, B, A		Color
	LUMINANCE		Component	Luminance value		Color
	LUMINANCE_ALPHA		Component	Luminance value, A	Color
	ABGR_EXT		Component	A, B, G, R		Color

	Table 3.5: DrawPixels and ReadPixels formats.  The third column
	gives a description of and the number and order of elements in a
	group.

Additions to Chapter 4 of the GL Specification (Per-Fragment Operations
and the Framebuffer)

    The new format is added to the discussion of Obtaining Pixels from the
    Framebuffer.  It should read " If the < format > is one of RED, GREEN,
    BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, and
    the GL is in color index mode, then the color index is obtained."

    The new format is added to the discussion of Index Lookup.  It should
    read "If < format > is one of RED, GREEN, BLUE, ALPHA, RGB, RGBA,
    ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, then the index is used to
    reference 4 tables of color components: PIXEL_MAP_I_TO_R,
    PIXEL_MAP_I_TO_G, PIXEL_MAP_I_TO_B, and PIXEL_MAP_I_TO_A."

Additions to Chapter 5 of the GL Specification (Special Functions)

    None

Additions to Chapter 6 of the GL Specification (State and State Requests)

    None

Additions to the GLX Specification

    None

GLX Protocol

    One entry is added to tables 1 and 5 in the GLX Protocol Specification:

	format				encoding
	------				--------
	GL_ABGR_EXT                     0x8000

    Table A.2 is also extended:

	format                          nelements
        ------                          --------
        GL_ABGR_EXT                     4


Errors

    None

New State

    None

New Implementation Dependent State

    None