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1Name
2
3    EXT_abgr
4
5Name Strings
6
7    GL_EXT_abgr
8
9Version
10
11    $Date: 1995/03/31 04:40:18 $ $Revision: 1.10 $
12
13Number
14
15    1
16
17Dependencies
18
19    None
20
21Overview
22
23    EXT_abgr extends the list of host-memory color formats.  Specifically,
24    it provides a reverse-order alternative to image format RGBA.  The ABGR
25    component order matches the cpack Iris GL format on big-endian machines.
26
27New Procedures and Functions
28
29    None
30
31New Tokens
32
33    Accepted by the <format> parameter of DrawPixels, GetTexImage,
34    ReadPixels, TexImage1D, and TexImage2D:
35
36        ABGR_EXT                     0x8000
37
38Additions to Chapter 2 of the GL Specification (OpenGL Operation)
39
40    None
41
42Additions to Chapter 3 of the GL Specification (Rasterization)
43
44    One entry is added to table 3.5 (DrawPixels and ReadPixels formats).
45    The new table is:
46
47                                                                        Target
48        Name                    Type            Elements                Buffer
49        ----                    ----            --------                ------
50        COLOR_INDEX             Index           Color Index             Color
51        STENCIL_INDEX           Index           Stencil value           Stencil
52        DEPTH_COMPONENT         Component       Depth value             Depth
53        RED                     Component       R                       Color
54        GREEN                   Component       G                       Color
55        BLUE                    Component       B                       Color
56        ALPHA                   Component       A                       Color
57        RGB                     Component       R, G, B                 Color
58        RGBA                    Component       R, G, B, A              Color
59        LUMINANCE               Component       Luminance value         Color
60        LUMINANCE_ALPHA         Component       Luminance value, A      Color
61        ABGR_EXT                Component       A, B, G, R              Color
62
63        Table 3.5: DrawPixels and ReadPixels formats.  The third column
64        gives a description of and the number and order of elements in a
65        group.
66
67Additions to Chapter 4 of the GL Specification (Per-Fragment Operations
68and the Framebuffer)
69
70    The new format is added to the discussion of Obtaining Pixels from the
71    Framebuffer.  It should read " If the <format> is one of RED, GREEN,
72    BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, and
73    the GL is in color index mode, then the color index is obtained."
74
75    The new format is added to the discussion of Index Lookup.  It should
76    read "If <format> is one of RED, GREEN, BLUE, ALPHA, RGB, RGBA,
77    ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA, then the index is used to
78    reference 4 tables of color components: PIXEL_MAP_I_TO_R,
79    PIXEL_MAP_I_TO_G, PIXEL_MAP_I_TO_B, and PIXEL_MAP_I_TO_A."
80
81Additions to Chapter 5 of the GL Specification (Special Functions)
82
83    None
84
85Additions to Chapter 6 of the GL Specification (State and State Requests)
86
87    None
88
89Additions to the GLX Specification
90
91    None
92
93GLX Protocol
94
95    One entry is added to tables 1 and 5 in the GLX Protocol Specification:
96
97        format                          encoding
98        ------                          --------
99        GL_ABGR_EXT                     0x8000
100
101    Table A.2 is also extended:
102
103        format                          nelements
104        ------                          --------
105        GL_ABGR_EXT                     4
106
107
108Errors
109
110    None
111
112New State
113
114    None
115
116New Implementation Dependent State
117
118    None
119