EXT_abgr
GL_EXT_abgr
$Date: 1995/03/31 04:40:18 $ $Revision: 1.10 $
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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 |
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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) |
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| Additions to Chapter 6 of the GL Specification (State and State Requests) |
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| Additions to the GLX Specification |
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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
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| New Implementation Dependent State |
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 |  | Last update: November 14, 2006.
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