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1Name
2
3    OES_read_format
4
5Name Strings
6
7    GL_OES_read_format
8
9Contact
10
11    Aaftab Munshi (amunshi@ati.com)
12
13Notice
14
15    Copyright (c) 2003-2013 The Khronos Group Inc. Copyright terms at
16        http://www.khronos.org/registry/speccopyright.html
17
18Specification Update Policy
19
20    Khronos-approved extension specifications are updated in response to
21    issues and bugs prioritized by the Khronos OpenGL ES Working Group. For
22    extensions which have been promoted to a core Specification, fixes will
23    first appear in the latest version of that core Specification, and will
24    eventually be backported to the extension document. This policy is
25    described in more detail at
26        https://www.khronos.org/registry/OpenGL/docs/update_policy.php
27
28Status
29
30    Revision 0.2 ratified by the Khronos BOP, July 23, 2003.
31    Revision 0.3 to be ratified
32
33Version
34
35    Last Modifed Date: Jan 4, 2006
36    Author Revision: 0.3
37
38Number
39
40    OpenGL ES Extension #17 (formerly OpenGL Extension #295)
41
42Dependencies
43
44    None
45    The extension is written against the OpenGL 1.3 Specification.
46
47Overview
48
49    This extension provides the capability to query an OpenGL
50    implementation for a preferred type and format combination
51    for use with reading the color buffer with the ReadPixels
52    command.  The purpose is to enable embedded implementations
53    to support a greatly reduced set of type/format combinations
54    and provide a mechanism for applications to determine which
55    implementation-specific combination is supported.
56
57    The preferred type and format combination returned may depend
58    on the read surface bound to the current GL context.
59
60IP Status
61
62    None
63
64Issues
65
66*   Should this be generalized for other commands: DrawPixels, TexImage?
67
68    Resolved: No need to aggrandize.
69
70New Procedures and Functions
71
72    None
73
74
75New Tokens
76
77    IMPLEMENTATION_COLOR_READ_TYPE_OES          0x8B9A
78    IMPLEMENTATION_COLOR_READ_FORMAT_OES        0x8B9B
79
80Additions to Chapter 2 of the OpenGL 1.3 Specification (OpenGL Operation)
81
82    None
83
84
85Additions to Chapter 3 of the OpenGL 1.3 Specification (Rasterization)
86
87    None
88
89
90Additions to Chapter 4 of the OpenGL 1.3 Specification (Per-Fragment
91Operations and the Frame Buffer)
92
93    Section 4.3 Drawing, Reading, and Copying Pixels
94
95      Section 4.3.2 Reading Pixels
96
97      (add paragraph)
98      A single format and type combination, designated the
99      preferred format, is associated with the state variables
100      IMPLEMENTATION_COLOR_READ_FORMAT_OES and
101      IMPLEMENTATION_COLOR_READ_TYPE_OES.  The preferred format
102      indicates a read format and type combination that provides optimal
103      performance, for the read surface that is bound to the current
104      GL context, for a particular implementation.  The state values
105      are chosen from the set of regularly accepted format
106      and type parameters as shown in tables 3.6 and 3.5.
107
108
109Additions to Chapter 5 of the OpenGL 1.3 Specification (Special Functions)
110
111      None
112
113Additions to Chapter 6 of the OpenGL 1.3 Specification (State and
114State Requests)
115
116      None
117
118Additions to Appendix A of the OpenGL 1.3 Specification (Invariance)
119
120    None
121
122Additions to the AGL/GLX/WGL Specifications
123
124    None
125
126Additions to the WGL Specification
127
128    None
129
130Additions to the AGL Specification
131
132    None
133
134Additions to Chapter 2 of the GLX 1.3 Specification (GLX Operation)
135
136Additions to Chapter 3 of the GLX 1.3 Specification (Functions and Errors)
137
138Additions to Chapter 4 of the GLX 1.3 Specification (Encoding on the X
139Byte Stream)
140
141Additions to Chapter 5 of the GLX 1.3 Specification (Extending OpenGL)
142
143Additions to Chapter 6 of the GLX 1.3 Specification (GLX Versions)
144
145GLX Protocol
146
147    TBD
148
149Errors
150
151    None
152
153New State
154
155    None
156
157New Implementation Dependent State
158
159(table 6.28)
160
161    Get Value     Type  Get Command  Value  Description  Sec.  Attribute
162    ---------     ----  -----------  -----  -----------  ----- ---------
163    x_FORMAT_OES  Z_11  GetIntegerv    -    read format  4.3.2    -
164    x_TYPE_OES    Z_20  GetIntegerv    -    read type    4.3.2    -
165
166    x_ = IMPLEMENTATION_COLOR_READ_
167
168Revision History
169
170    02/20/2003    0.1
171        - Original draft.
172
173    07/08/2003    0.2
174        - Marked issue regarding extending to other commands to resolved.
175        - Hackery to make state table fit in 80 columns
176        - Removed Dependencies on section
177        - Added extension number and enumerant values
178
179    01/04/2006    0.3
180        - Added clarification that format and type value returned
181          depends on the current read surface attached to the current context
182