xref: /third_party/openGLES/extensions/EXT/EXT_texture_buffer.txt (revision 5bd8dead)

Name

    EXT_texture_buffer

Name Strings

    GL_EXT_texture_buffer

Contact

    Jon Leech (oddhack 'at' sonic.net)
    Daniel Koch, NVIDIA (dkoch 'at' nvidia.com)

Contributors

    Pat Brown, NVIDIA
    James Helferty, NVIDIA
    Graham Connor, Imagination
    Ben Bowman, Imagination
    Jonathan Putsman, Imagination
    Piotr Czubak, Intel
    Marcin Kantoch, Mobica
    Contributors to ARB_texture_buffer_object
    Contributors to ARB_texture_buffer_range

Notice

    Copyright (c) 2008-2013 The Khronos Group Inc. Copyright terms at
        http://www.khronos.org/registry/speccopyright.html

    Portions Copyright (c) 2013-2014 NVIDIA Corporation.

Status

    Complete.

Version

    Last Modified Date: July 14, 2014
    Revision: 14

Number

    OpenGL ES Extension #183

Dependencies

    OpenGL ES 3.1 and OpenGL ES Shading Language 3.10 are required.

    This specification is written against the OpenGL ES 3.1 (March 17,
    2014) and OpenGL ES 3.10 Shading Language (March 17, 2014)
    Specifications.

    This extension interacts with OES_shader_image_atomic.

Overview

    This extension provides a new texture type, called a buffer texture.
    Buffer textures are one-dimensional arrays of texels whose storage comes
    from an attached buffer object. When a buffer object is bound to a
    buffer texture, a format is specified, and the data in the buffer object
    is treated as an array of texels of the specified format.

    The use of a buffer object to provide storage allows the texture data to
    be specified in a number of different ways: via buffer object loads
    (BufferData), direct CPU writes (MapBuffer), or framebuffer readbacks to
    pixel buffer objects (ReadPixels). A buffer object can also be loaded by
    transform feedback, which captures
    selected transformed attributes of vertices processed by the GL. Several
    of these mechanisms do not require an extra data copy, which would be
    required when using conventional TexImage-like entry points.

    Buffer textures do not support mipmapping, texture lookups with
    normalized floating-point texture coordinates, and texture filtering of
    any sort.
    They can be accessed via single texel fetch operations in programmable
    shaders, using a new sampler type and texel fetch function, and
    access can be controlled using the same memory barrier operations
    as for other texture types.

    Buffer textures are treated as (potentially large) one-dimensional
    textures; the maximum texture size supported for buffer textures in the
    initial implementation of this extension is 2^27 texels (note that this
    extension only guarantees support for buffer textures with 2^16 texels,
    but we expect most implementations to exceed that substantially). When a
    buffer object is attached to a buffer texture, a size is not specified;
    rather, the number of texels in the texture is taken by dividing the size
    of the buffer object by the size of each texel.

    This extension also allows a sub-range of the buffer's data store to
    be attached to a texture. This can be used, for example, to allow multiple
    buffer textures to be backed by independent sub-ranges of the same buffer
    object, or for different sub-ranges of a single buffer object to be used
    for different purposes.

New Procedures and Functions

    void TexBufferEXT(enum target, enum internalformat, uint buffer);

    void TexBufferRangeEXT(enum target, enum internalformat, uint buffer,
                           intptr offset, sizeiptr size);

New Tokens

    Accepted by the <target> parameter of BindBuffer, BufferData,
    BufferSubData, MapBufferRange, BindTexture, UnmapBuffer,
    GetBufferParameteriv, GetBufferPointerv, TexBufferEXT, and
    TexBufferRangeEXT:

        TEXTURE_BUFFER_EXT                              0x8C2A

    Accepted by the <pname> parameters of GetBooleanv, GetFloatv, and
    GetIntegerv:

        TEXTURE_BUFFER_BINDING_EXT                      0x8C2A
            (note that this token name is an alias for TEXTURE_BUFFER_EXT,
            and is used for naming consistency with queries for the buffers
            bound to other buffer binding points).
        MAX_TEXTURE_BUFFER_SIZE_EXT                     0x8C2B
        TEXTURE_BINDING_BUFFER_EXT                      0x8C2C
        TEXTURE_BUFFER_OFFSET_ALIGNMENT_EXT             0x919F

    Returned in the <type> parameter of GetActiveUniform, the <params>
    parameter of GetActiveUniformsiv, and the <params> parameter of
    GetProgramResourceiv when the TYPE property is queried on the
    UNIFORM interface:

        SAMPLER_BUFFER_EXT                              0x8DC2
        INT_SAMPLER_BUFFER_EXT                          0x8DD0
        UNSIGNED_INT_SAMPLER_BUFFER_EXT                 0x8DD8
        IMAGE_BUFFER_EXT                                0x9051
        INT_IMAGE_BUFFER_EXT                            0x905C
        UNSIGNED_INT_IMAGE_BUFFER_EXT                   0x9067

    Accepted by the <pname> parameter of GetTexLevelParameter:

        TEXTURE_BUFFER_DATA_STORE_BINDING_EXT           0x8C2D
        TEXTURE_BUFFER_OFFSET_EXT                       0x919D
        TEXTURE_BUFFER_SIZE_EXT                         0x919E

Additions to the OpenGL ES 3.1 Specification

    Modify section 6.1 "Creating and Binding Buffer Objects"

    Add to table 6.1 "Buffer object binding targets":

        Target Name         Purpose             Described in section(s)
        ------------------  ------------------- -----------------------
        TEXTURE_BUFFER_EXT  Texture data buffer 8.8tbo


    Modify section 7.3 "Program Objects"

    Add to table 7.3 "OpenGL ES Shading Language type tokens...":

        Type Name Token                         Keyword
        --------------------------------------- ---------------------------
        SAMPLER_BUFFER_EXT                      samplerBuffer
        INT_SAMPLER_BUFFER_EXT                  isamplerBuffer
        UNSIGNED_INT_SAMPLER_BUFFER_EXT         usamplerBuffer
        IMAGE_BUFFER_EXT                        imageBuffer
        INT_IMAGE_BUFFER_EXT                    iimageBuffer
        UNSIGNED_INT_IMAGE_BUFFER_EXT           uimageBuffer


    Modify section 7.11 "Shader Memory Access"

    Change the description of TEXTURE_FETCH_BARRIER_BIT for MemoryBarrier on
    p. 116:

      * TEXTURE_FETCH_BARRIER_BIT: Texture fetches from shaders, including
        fetches from buffer object memory via buffer textures, after the
        barrier will reflect data written by shaders prior to the barrier.


    Modify chapter 8 "Textures and Samplers"

    Add to the fourth paragraph of the section, on p. 128:

    ... six faces of the cube. Buffer textures are special one-dimensional
    textures whose texel arrays are stored in separate buffer objects.


    Modify section 8.1 "Texture Objects"

    Change the first paragraph of the section on p. 129:

    ... The default texture object is bound to each of the TEXTURE_2D,
    TEXTURE_3D, TEXTURE_2D_ARRAY, TEXTURE_CUBE_MAP, TEXTURE_2D_MULTISAMPLE,
    and TEXTURE_BUFFER_EXT targets ...


    Change the paragaph following the description of IsTexture on p. 131:

    The texture object name space, including the initial two-, and three-
    dimensional, two-dimensional array, cube map, two-dimensional
    multisample, and buffer texture objects, is shared among all texture
    units. ...


    Add new section 8.8tbo following section 8.8 "Multisample Textures":

    8.8tbo Buffer Textures

    In addition to the types of textures described in previous sections, one
    additional type of texture is supported. A <buffer texture> is a
    one-dimensional texture, consisting of a one-dimensional texel array.
    Unlike other texture types, the texel array is not stored as part of the
    texture. Instead, a buffer object is attached to a buffer texture and
    the texel array is taken from that buffer object's data store. When the
    contents of a buffer object's data store are modified, those changes are
    reflected in the contents of any buffer texture to which the buffer
    object is attached. Buffer textures do not have multiple image levels;
    only a single data store is available.

    The command

      void TexBufferRangeEXT(enum target, enum internalformat, uint buffer,
                               intptr offset, sizeiptr size);

    attaches the range of the storage for the buffer object named <buffer>
    for <size> basic machine units, starting at <offset> (also in basic
    machine units) to the active buffer texture, and specifies an internal
    format for the texel array found in the range of the attached buffer
    object. If <buffer> is zero, then any buffer object attached to the
    buffer texture is detached, the values <offset> and <size> are ignored
    and the state for <offset> and <size> for the buffer texture are reset
    to zero. <target> must be TEXTURE_BUFFER_EXT. <internalformat> specifies
    the storage format and must be one of the sized internal formats found
    in Table texbo.1.

    Errors

    An INVALID_ENUM error is generated if <target> is not
    TEXTURE_BUFFER_EXT.

    An INVALID_ENUM error is generated if <internalformat> is not one of the
    sized internal formats found in Table texbo.1.

    An INVALID_OPERATION error is generated if <buffer> is non-zero, but is
    not the name of an existing buffer object.

    An INVALID_VALUE error is generated if <offset> is negative, if <size>
    is less than or equal to zero, or if <offset> + <size> is greater than
    the value of BUFFER_SIZE for the buffer bound to <target>.

    An INVALID_VALUE error is generated if <offset> is not an integer
    multiple of the value of TEXTURE_BUFFER_OFFSET_ALIGNMENT_EXT.


    The command

      void TexBufferEXT(enum target, enum internalformat, uint buffer);

    is equivalent to

      TexBufferRangeEXT(target, internalformat, buffer, 0, size);

    with <size> set to the value of BUFFER_SIZE for <buffer>.

    When a range of the storage of a buffer object is attached to a buffer
    texture, the range of the buffer's data store is taken as the texture's
    texel array. The number of texels in the buffer texture's texel array is
    given by

      floor(<size> / (<components> * sizeof(<base_type>)),

    where <components> and <base_type> are the element count and base data
    type for elements, as specified in Table texbo.1.

    The number of texels in the texel array is then clamped to the value of
    the implementation-dependent limit MAX_TEXTURE_BUFFER_SIZE_EXT. When a
    buffer texture is accessed in a shader, the results of a texel fetch are
    undefined if the specified texel coordinate is negative, or greater than
    or equal to the clamped number of texels in the texel array.

    When a buffer texture is accessed in a shader, an integer is provided to
    indicate the texel coordinate being accessed. If no buffer object is
    bound to the buffer texture, the results of the texel access are
    undefined. Otherwise, the attached buffer object's data store is
    interpreted as an array of elements of the GL data type corresponding to
    <internalformat>. Each texel consists of one to four elements that are
    mapped to texture components (R, G, B, and A). Element <m> of the texel
    numbered <n> is taken from element <n> * <components> + <m> of the
    attached buffer object's data store. Elements and texels are both
    numbered starting with zero. For texture formats with signed or unsigned
    normalized fixed-point components, the extracted values are converted to
    floating-point values using equations 2.2 or 2.1 respectively. The
    components of the texture are then converted to an (R,G,B,A) vector
    according to Table texbo.1, and returned to the shader as a
    four-component result vector with components of the appropriate data
    type for the texture's internal format. The base data type, component
    count, normalized component information, and mapping of data store
    elements to texture components is specified in Table texbo.1.

                                                       Component
    Sized Internal Format Base Type  Components  Norm   0 1 2 3
    --------------------- ---------  ----------  ----  ---------
    R8                    ubyte      1           Yes    R 0 0 1
    R16F                  half       1           No     R 0 0 1
    R32F                  float      1           No     R 0 0 1
    R8I                   byte       1           No     R 0 0 1
    R16I                  short      1           No     R 0 0 1
    R32I                  int        1           No     R 0 0 1
    R8UI                  ubyte      1           No     R 0 0 1
    R16UI                 ushort     1           No     R 0 0 1
    R32UI                 uint       1           No     R 0 0 1
    RG8                   ubyte      2           Yes    R G 0 1
    RG16F                 half       2           No     R G 0 1
    RG32F                 float      2           No     R G 0 1
    RG8I                  byte       2           No     R G 0 1
    RG16I                 short      2           No     R G 0 1
    RG32I                 int        2           No     R G 0 1
    RG8UI                 ubyte      2           No     R G 0 1
    RG16UI                ushort     2           No     R G 0 1
    RG32UI                uint       2           No     R G 0 1
    RGB32F                float      3           No     R G B 1
    RGB32I                int        3           No     R G B 1
    RGB32UI               uint       3           No     R G B 1
    RGBA8                 ubyte      4           Yes    R G B A
    RGBA16F               half       4           No     R G B A
    RGBA32F               float      4           No     R G B A
    RGBA8I                byte       4           No     R G B A
    RGBA16I               short      4           No     R G B A
    RGBA32I               int        4           No     R G B A
    RGBA8UI               ubyte      4           No     R G B A
    RGBA16UI              ushort     4           No     R G B A
    RGBA32UI              uint       4           No     R G B A
        Table texbo.1, Internal Formats for Buffer Textures. For each
        format, the data type of each element is indicated in the "Base
        Type" column and the element count is in the "Components" column.
        The "Norm" column indicates whether components should be treated as
        normalized floating-point values. The "Component 0, 1, 2, and 3"
        columns indicate the mapping of each element of a texel to texture
        components.

    In addition to attaching buffer objects to textures, buffer objects can
    be bound to the buffer object target named TEXTURE_BUFFER_EXT, in order
    to specify, modify, or read the buffer object's data store. The buffer
    object bound to TEXTURE_BUFFER_EXT has no effect on rendering. A buffer
    object is bound to TEXTURE_BUFFER_EXT by calling BindBuffer with
    <target> set to TEXTURE_BUFFER_EXT, as described in chapter 6.


    Modify section 8.10.3 "Texture Level Parameter Queries"

    Modify the second and third paragraphs in the description of
    GetTexLevelParameter*, on p. 173:

    "<target> may be ... TEXTURE_2D_ARRAY, TEXTURE_BUFFER_EXT, one of the
    cube map face ... indicating the ... two-dimensional array texture,
    buffer texture, one of the six distinct ...

    <lod> determines which level-of-detail's state is returned. If <target>
    is TEXTURE_BUFFER_EXT, <lod> must be zero."


    Modify section 8.18 "Texture State"

    Change the first paragraph of the section on p. 191:

    ... Each array has associated with it a width, height (except for buffer
    textures), and depth ... a boolean describing whether the image is
    compressed or not, an integer size of a compressed image, and an integer
    containing the name of a buffer object bound as the data store of the
    image.

    Each inital texel array is null ... the compressed flag set to FALSE, a
    zero compressed size, and the bound buffer object name is zero.

    Buffer textures also contain two pointer sized integers containing the
    offset and range of the buffer object's data store.


    Modify section 8.22 "Texture Image Loads and Stores"

    On p. 197 in the errors section for BindImageTexture, replace the
    last error with the following:

    An INVALID_OPERATION error is generated if <texture> is neither the
    name of a buffer texture, nor the name of an immutable texture object.

    Add to table 8.26 "Mapping of image load, store..."

        Texture target               face/
                                   i  j  k  layer
        -------------------------- -- -- -- -----
        TEXTURE_BUFFER_EXT         x  -  -  -


New State

    Add to table 20.8 "Textures (selector, state per texture unit)"

                                                              Initial
    Get Value                           Type     Get Command  Value       Description                   Sec.
    ----------------------------------  -------- -----------  ----------  ----------------------------  -----
    TEXTURE_BINDING_BUFFER_EXT          48* x Z+ GetIntegerv  0           Texture object bound          8.1
                                                                          to TEXTURE_BUFFER_EXT

    Add to table 20.10 "Textures (state per texture image)"

                                                                    Initial
    Get Value                             Type  Get Command          Value   Description                 Sec.
    ------------------------------------- ----- -------------------- ------- --------------------------- --------
    TEXTURE_BUFFER_DATA_STORE_BINDING_EXT Z+    GetTexLevelParameter 0       Buffer object bound to the  8.8tbo
                                                                             data store for the active
                                                                             image unit's buffer texture
    TEXTURE_BUFFER_OFFSET_EXT             n x Z GetTexLevelParameter 0       Offset into buffer's data   8.8tbo
                                                                             store used for the active
                                                                             image unit's buffer texture
    TEXTURE_BUFFER_SIZE_EXT               n x Z GetTexLevelParameter 0       Size of the buffer's data   8.8tbo
                                                                             store used for the active
                                                                             image unit's buffer texture

    Modify the TEXTURE_INTERNAL_FORMAT entry in table 20.10

                                                                    Initial
    Get Value                           Type   Get Command          Value   Description                 Sec.
    ----------------------              ----   -------------------- ------- --------------------------- ------
    TEXTURE_INTERNAL_FORMAT             E      GetTexLevelParameter RGBA    Internal format[fn1]        8
                                                                    or R8
        [fn1] The initial internal format is R8 for texture buffer object
        images, RGBA for all other texture images.


    Add to table 20.50 "Miscellaneous"

                                                           Initial
    Get Value                           Type   Get Command Value   Description                 Sec.
    --------------------------          ----   ----------- ------- --------------------------- ----
    TEXTURE_BUFFER_BINDING_EXT          Z+     GetIntegerv 0       Buffer object bound to      6.1
                                                                   generic buffer texture
                                                                   binding point


New Implementation Dependent State

    Add to table 20.41 "Implementation Dependent Values (cont.)"

                                                           Minimum
    Get Value                           Type  Get Command  Value    Description            Sec.
    ----------------------------------- ----  -----------  -------  ---------------------  --------
    MAX_TEXTURE_BUFFER_SIZE_EXT         Z+    GetIntegerv  65536    No. of addressable     8.8tbo
                                                                    texels for buffer
                                                                    textures
    TEXTURE_BUFFER_OFFSET_ALIGNMENT_EXT Z+    GetIntegerv  256 (**) Minimum required       8.8tbo
                                                                    alignment for texture
                                                                    buffer offsets

    (**) the value of TEXTURE_BUFFER_OFFSET_ALIGNMENT_EXT is the largest
    allowed value.  Smaller values are permitted.

Modifications to the OpenGL ES Shading Language Specification, Version 3.10

    #extension GL_EXT_texture_buffer: <behavior>

    The above line is needed to control the GLSL features described in
    this section.


    A new preprocessor #define is added to the OpenGL ES Shading Language:

      #define GL_EXT_texture_buffer 1


    Add the following keywords to section 3.7 "Keywords" on p. 14 and
    remove them from the list of reserved keywords on p. 15:

    samplerBuffer
    isamplerBuffer
    usamplerBuffer
    imageBuffer
    iimageBuffer
    uimageBuffer


    Add to section 4.1 "Basic Types"

    Add to table "Floating Point Sampler Types (opaque)" on p. 20:

    Type                    Meaning
    ----------------------  ---------------------------------------
    samplerBuffer           a handle for accessing a buffer texture
    imageBuffer

    Add to table "Signed Integer Sampler Types (opaque)" on p. 21:

    Type                    Meaning
    ----------------------- ----------------------------------------
    isamplerBuffer          a handle for accessing an integer buffer
    iimageBuffer            texture

    Add to table "Unsigned Integer Sampler Types (opaque)" on p. 21:

    Type                    Meaning
    ----------------------- ------------------------------------------
    usamplerBuffer          a handle for accessing an unsigned integer
    uimageBuffer            buffer texture


    Modify section 4.7.4 "Default Precision Qualifiers"

    Add the following types to the list of types which have no default
    precision qualifiers at the top of p. 65:

    samplerBuffer
    isamplerBuffer
    usamplerBuffer
    imageBuffer
    iimageBuffer
    uimageBuffer


    Modify section 8.9 "Texture Functions"

    Add at the end of the paragraph starting "In all functions below" on p.
    119:

    ... performing the texture access operation. No <bias> or <lod>
    parameters for multisample textures or texture buffers are supported,
    because mipmaps are not allowed for these types of textures.


    Add to the table of Texture Query Functions in section 8.9.1 on p. 120:

      highp int textureSize(gsamplerBuffer sampler)


    Add to the table of Texel Lookup Functions in section 8.9.2 on p. 121:

      gvec4 texelFetch(gsamplerBuffer sampler, int P)


    Modify section 8.14 "Image Functions":

    Add to the description of the IMAGE_INFO placeholder in the fourth
    paragraph of the section, on p. 132:

    The "IMAGE_INFO" in the prototypes below is a placeholder ...

        gimage2DArray image, ivec3 coord
        gimageBuffer image, int P


    Add to the table of image functions on p. 133:

        highp int imageSize(readonly writeonly gimageBuffer image)


    Change the introduction of section 8.16 "Shader Memory Control
    Functions":

    Shaders of all types may read and write the contents of textures and
    buffer objects using image variables. While the order of reads ...


Dependencies on OES_shader_image_atomic

    When OES_shader_image_atomic is supported, all the imageAtomic* functions
    are supported on image buffers.


Issues

    Note: These issues apply specifically to the definition of the
    EXT_texture_buffer specification, which is based on the OpenGL
    extension ARB_texture_buffer_object as updated in OpenGL 4.x. Resolved
    issues from ARB_texture_buffer_object have been removed (with the
    exception of issue 6, which is copied from issue 12 of the ARB
    extension), but remain largely applicable to this extension.
    ARB_texture_buffer_object can be found in the OpenGL Registry.

    (1) What functionality was removed from ARB_texture_buffer_object?

      - Support for sized buffer formats R16, RG16, and RGBA16, and for
        MapBuffer and GetBufferSubData is removed since they do not exist
        in ES 3.0.
      - Support for ALPHA and LUMINANCE buffer textures is removed since
        they are legacy formats in ES 3.0, and there are no sized ALPHA or
        LUMINANCE formats.
      - GL 4.4 extended support for buffer textures to the
        GetInternalformativ query <target>, but that command in ES 3.0 is
        restricted to returning multisampling information, which is
        irrelevant to buffer textures.
      - Support for TEXTURE_BUFFER_FORMAT is removed. Use the
        GetTexLevelParameter* TEXTURE_INTERNAL_FORMAT query instead.

    (2) What functionality was changed and added relative to
        ARB_texture_buffer_object?

      - EXT_texture_buffer more closely matches OpenGL 4.4 language,
        rather than ARB_texture_buffer_object language.
        * Support for querying buffer texture state with
          GetTexLevelParameter* is added
        * Support for sized R, RG, and RGB formats is added. Per issue (2)
          of ARB_texture_buffer_object, some formats supported by ES 3.0 but
          which may present hardware difficulties are not supported,
          including R*8_SNORM and all RGB formats other than RGB32*.
      - Interactions were added with OpenGL ES 3.1 and other EXT extension
        functionality, primarily shader memory access as well as texture
        level parameter queries.
      - incorporates the ability to bind a sub-range of a buffer from
        ARB_texture_buffer_range.

    (3) What should the rules on GLSL suffixing be?

    RESOLVED: The new sampler and image types are reserved keywords in
    ESSL 3.00 so they can be use without prefix/suffixes.

    (4) Do we want the ARB_texture_buffer_range functionality present in GL
        4.4? This adds useful functionality (backing the buffer texture with
        a selected part of a buffer object) at low increase in complexity of
        the spec.

    RESOLVED: Yes, this functionality is included in this extension.

    (5) How is the various buffer texture-related state queried?

        There are three pieces of state that can be queried:
            (a) the texture object bound to buffer texture binding point for
                the active texture image unit (TEXTURE_BINDING_BUFFER_EXT).
            (b) the buffer object whose data store was used by that texture
                object (TEXTURE_BUFFER_DATA_STORE_BINDING_EXT).
            (c) the buffer object bound to the TEXTURE_BUFFER_EXT binding
                point (TEXTURE_BUFFER_BINDING_EXT).

        The first and last are queried with GetIntegerv, but the second is
        queried with GetTexLevelParameter. Note that for (a) and (b), the
        texture queried is the one bound to TEXTURE_BUFFER_EXT on the active
        texture image unit.

    (6) Should the R16, RG16 and RGBA16 texture formats be supported?

    RESOLVED.  No. OpenGL ES 3.0 does not support these formats. They were
    considered for late addition to OpenGL ES 3.1 in Bug 11366, but didn't
    make the cut. In the absence of another extension to add them, they
    are not supported here either.

    (7) OpenGL ES 3.1 does not allow images to be created from mutable
    textures (ie those created with TexImage). How does this affect
    this extension?

    RESOLVED. Buffer textures would technically be considered mutable
    since they are not defined by a TexStorage command and it is possible
    to redefine the buffer storage which backs them. However there is
    currently no ES API for creating immutable buffers
    (ARB_buffer_storage does this for GL) and thus we must allow mutable
    buffers to back buffer textures.

    (8) This extension is called EXT_texture_buffer, but the desktop name
    is {EXT,ARB}_texture_buffer_object. Is the name change intentional?

    RESOLVED. Yes. We want to avoid extensions in ES and GL that have the
    same name, but not the same functionality (except as a subset).

    EXT_texture_buffer includes the functionality of ARB_texture_buffer_object,
    ARB_texture_buffer_range, and  ARB_texture_buffer_rgb32, along with some
    changes that were made with how those operate GL 4.4.  It would have been
    too messy and confusing to try to incorporate all these into the existing
    EXT_texture_buffer_object spec from GL as interactions with ES.


Revision History

    Rev.  Date     Author    Changes
    ----  -------- --------- ---------------------------------------------
    14    07/14/14 dkoch     Clarify that TEXTURE_BUFFER_DATA_STORE_BINDING_EXT
                             is queried with GetTexLevelParameter not
                             GetIntegerv (Bug 12343). Fix types in unsigned
                             sampler types table (Bug 12356)
    13    05/14/14 dkoch     Add issue 8.
    12    05/05/14 dkoch     Clarify OFFSET_ALIGNMENT (Bug 11962)
    11    03/28/14 dkoch     Correct texture function prototypes
    10    03/26/14 Jon Leech Sync with released ES 3.1 specs. Reflow text.
    9     03/26/14 dkoch     Update contributors, clarify no default precision
                             Allow mutable buffer images (Issue 7).
    8     03/10/14 Jon Leech Rebase on OpenGL ES 3.1 specs and change
                             extension suffix to EXT.
    7     02/24/14 dkoch     Interactions with OES_shader_image_atomic
                             Added missing entry-point modifications
                             Clarified overview. Fix typo.
    6     02/12/14 dkoch     Resolved issue 7.
    5     12/16/13 dkoch     Add TexBufferRange functionality
                             Minor changes for consistency with GL 4.4
                             Resolved Issue 5, add issue 7.
    4     11/21/13 dkoch     Remove mention of a few features not in ES
                             A few typographical fixes.
    3     11/15/13 dkoch     Rename to texture_buffer
                             Correct issue 4 and keyword use.
    2     11/20/13 Jon Leech Minor updates
        - Explain default TEXTURE_INTERNAL_FORMAT for texbos (see Bug
          10185).
        - Sync with XXX spec language update.
        - Refer to ES 3.1 instead of ES 3plus.

    1    11/12/13 Jon Leech Initial version based on
                            ARB_texture_buffer_object.