OES_read_format

Name

OES_read_format

Name Strings

GL_OES_read_format

Contact

Aaftab Munshi (amunshi@ati.com)

Notice

Copyright (c) 2003-2013 The Khronos Group Inc. Copyright terms at
    http://www.khronos.org/registry/speccopyright.html

Specification Update Policy

Khronos-approved extension specifications are updated in response to
issues and bugs prioritized by the Khronos OpenGL ES Working Group. For
extensions which have been promoted to a core Specification, fixes will
first appear in the latest version of that core Specification, and will
eventually be backported to the extension document. This policy is
described in more detail at
    https://www.khronos.org/registry/OpenGL/docs/update_policy.php

Status

Revision 0.2 ratified by the Khronos BOP, July 23, 2003.
Revision 0.3 to be ratified

Version

Last Modifed Date: Jan 4, 2006
Author Revision: 0.3

Number

OpenGL ES Extension #17 (formerly OpenGL Extension #295)

Dependencies

None
The extension is written against the OpenGL 1.3 Specification.

Overview

This extension provides the capability to query an OpenGL
implementation for a preferred type and format combination
for use with reading the color buffer with the ReadPixels
command.  The purpose is to enable embedded implementations
to support a greatly reduced set of type/format combinations
and provide a mechanism for applications to determine which
implementation-specific combination is supported.

The preferred type and format combination returned may depend
on the read surface bound to the current GL context.

IP Status

None

Issues

  • Should this be generalized for other commands: DrawPixels, TexImage?

    Resolved: No need to aggrandize.

New Procedures and Functions

None

New Tokens

IMPLEMENTATION_COLOR_READ_TYPE_OES          0x8B9A
IMPLEMENTATION_COLOR_READ_FORMAT_OES        0x8B9B

Additions to Chapter 2 of the OpenGL 1.3 Specification (OpenGL Operation)

None

Additions to Chapter 3 of the OpenGL 1.3 Specification (Rasterization)

None

Additions to Chapter 4 of the OpenGL 1.3 Specification (Per-Fragment Operations and the Frame Buffer)

Section 4.3 Drawing, Reading, and Copying Pixels

  Section 4.3.2 Reading Pixels

  (add paragraph)
  A single format and type combination, designated the
  preferred format, is associated with the state variables
  IMPLEMENTATION_COLOR_READ_FORMAT_OES and
  IMPLEMENTATION_COLOR_READ_TYPE_OES.  The preferred format
  indicates a read format and type combination that provides optimal
  performance, for the read surface that is bound to the current 
  GL context, for a particular implementation.  The state values
  are chosen from the set of regularly accepted format
  and type parameters as shown in tables 3.6 and 3.5.

Additions to Chapter 5 of the OpenGL 1.3 Specification (Special Functions)

  None

Additions to Chapter 6 of the OpenGL 1.3 Specification (State and State Requests)

  None

Additions to Appendix A of the OpenGL 1.3 Specification (Invariance)

None

Additions to the AGL/GLX/WGL Specifications

None

Additions to the WGL Specification

None

Additions to the AGL Specification

None

Additions to Chapter 2 of the GLX 1.3 Specification (GLX Operation)

Additions to Chapter 3 of the GLX 1.3 Specification (Functions and Errors)

Additions to Chapter 4 of the GLX 1.3 Specification (Encoding on the X Byte Stream)

Additions to Chapter 5 of the GLX 1.3 Specification (Extending OpenGL)

Additions to Chapter 6 of the GLX 1.3 Specification (GLX Versions)

GLX Protocol

TBD

Errors

None

New State

None

New Implementation Dependent State

(table 6.28)

Get Value     Type  Get Command  Value  Description  Sec.  Attribute
---------     ----  -----------  -----  -----------  ----- ---------
x_FORMAT_OES  Z_11  GetIntegerv    -    read format  4.3.2    -
x_TYPE_OES    Z_20  GetIntegerv    -    read type    4.3.2    -

x_ = IMPLEMENTATION_COLOR_READ_

Revision History

02/20/2003    0.1
    - Original draft.

07/08/2003    0.2
    - Marked issue regarding extending to other commands to resolved.
    - Hackery to make state table fit in 80 columns
    - Removed Dependencies on section
    - Added extension number and enumerant values

01/04/2006    0.3
    - Added clarification that format and type value returned
      depends on the current read surface attached to the current context