Name

    ANGLE_memory_size

Name Strings

    GL_ANGLE_memory_size

Contributors

    Geoff Lang

Contact

    Geoff Lang (geofflang 'at' google.com)

Notice

    Copyright (c) 2018 The Khronos Group Inc. Copyright terms at
        http://www.khronos.org/registry/speccopyright.html

Status

    Draft

Version

    Version 1, November 1, 2018

Number

    OpenGL ES Extension #??

Dependencies

    Requires OpenGL ES 2.0

    Written against the OpenGL ES 3.1 specification.

Overview

    This extension allows the user to query the estimated memory internally
    allocated for an OpenGL resource. This information can be useful for
    determining which resources should be deleted under memory pressure.

New Procedures and Functions

    None

New Tokens

    Accepted by the <name> parameter of GetTexParameter*,
    GetTexLevelParameter*, GetBufferParameter* and GetRenderbufferParameter*
    functions:

        GL_MEMORY_SIZE_ANGLE              0x93AD

Additions to the OpenGL ES 3.1 Specification

    Add an entry to Table 6.2, Buffer object parameters and their values:

    Name              Type  Initial Value Legal Values
    ----------------- ----- ------------- ------------------------
    MEMORY_SIZE_ANGLE int64 0             any non-negative integer

    Change the last sentence of the first paragraph of section 8.10.2,
    Texture Parameter Queries:

    - pname must be IMAGE_FORMAT_COMPATIBILITY_TYPE, TEXTURE_-
    - IMMUTABLE_FORMAT, TEXTURE_IMMUTABLE_LEVELS, or one of the symbolic
    - values in table 8.20.
    + pname must be IMAGE_FORMAT_COMPATIBILITY_TYPE, TEXTURE_-
    + IMMUTABLE_FORMAT, TEXTURE_IMMUTABLE_LEVELS, MEMORY_SIZE_ANGLE,
    + or one of the symbolic values in table 8.20.

    Add to the end of the fifth paragraph of section 8.10.3, Texture Level
    Parameter Queries:

    + queries of pname MEMORY_SIZE_ANGLE return the estimated number of bytes
    + allocated for level of the texture bound to target.

    Add a new paragraph after paragraph 3 in section 9.2.6, Renderbuffer
    Object Queries:

    If pname is MEMORY_SIZE_ANGLE, then params will contain the esimated
    number of bytes allocated for the renderbuffer bound to target.

New State

    Add to Table 20.4: Buffer Object State

    Get value           Type Get Cmd                Min Value Description               Sec.
    ------------------- ---- ---------------------  --------- ------------------------- ----
    MEMORY_SIZE_ANGLE   Z+   GetBufferParameter64v  -         Estimated bytes allocated 6

    Add to Table 20.9: Textures (state per texture object)

    Get value           Type Get Cmd               Min Value Description               Sec.
    ------------------- ---- --------------------  --------- ------------------------- -----
    MEMORY_SIZE_ANGLE   Z+   GetTexParameter       -         Estimated bytes allocated 6.1.3
                             GetTexLevelParameter

    Add to Table 20.16: Renderbuffer (state per renderbuffer object)

    Get value           Type Get Cmd                     Min Value Description               Sec.
    ------------------- ---- --------------------------  --------- ------------------------- -----
    MEMORY_SIZE_ANGLE   Z+   GetRenderbufferParameteriv  -         Estimated bytes allocated 9.2.6


Interactions with the OpenGL ES 2.0 and 3.0 specifications:

    Remove all references to GetTexLevelParameter and replace references to
    GetBufferParameter64v with GetBufferParameteriv.

Issues

    (1) Could the estimated number of bytes be specified more tightly to an
        upper or lower bound?

        RESOLVED: Implementations should attempt to return the lower bound on
        the allocated memory if exact numbers are not known. The lower bound is
        the most actionable value for making decisions when caching.

Revision History

    Rev.    Date         Author     Changes
    ----  -------------  ---------  ----------------------------------------
      1    Nov 1, 2018   geofflang  Initial version