extensions/EGL_ANGLE_metal_texture_client_buffer.txt

Name

    ANGLE_metal_texture_client_buffer

Name Strings

    EGL_ANGLE_metal_texture_client_buffer

Contributors

    Le Hoang Quyen
    Dan Glastonbury

Contacts

    Jamie Madill, Google (jmadill 'at' google 'dot' com)
    Le Hoang Quyen (lehoangq 'at' gmail.com)
    Dan Glastonbury, Apple (djg 'at' apple 'dot' com)

Status

    Draft

Version
    Version 3, Feb 20, 2024

Number

    EGL Extension #??

Dependencies

    This extension is written against the wording of the EGL 1.4
    Specification.

    References the EGL_ANGLE_iosurface_client_buffer extension.

Overview

    This extension allows creating EGL images from external metal texture objects.

New Types

    None

New Procedures and Functions

    None

New Tokens

    Accepted in the <target> parameter of eglCreateImageKHR:

        EGL_METAL_TEXTURE_ANGLE               0x34A7

    Accepted as an attribute in the <attrib_list> parameter of
    eglCreateImageKHR:

        EGL_METAL_TEXTURE_ARRAY_SLICE_ANGLE   0x34DD

Additions to Chapter 2 of the EGL 1.2 Specification (EGL Operation)

    Add to section 2.5.1 "EGLImage Specification" (as defined by the
    EGL_KHR_image_base specification), in the description of
    eglCreateImageKHR:

   "Values accepted for <target> are listed in Table aaa, below.

      +--------------------------------------+-----------------------------------------+
      |  <target>                            |  Notes                                  |
      +--------------------------------------+-----------------------------------------+
      |  EGL_METAL_TEXTURE_ANGLE             |  Used for Metal texture objects         |
      +--------------------------------------+-----------------------------------------+
       Table aaa.  Legal values for eglCreateImageKHR <target> parameter

    ...

    Attribute names accepted in <attrib_list> are shown in Table bbb,
    together with the <target> for which each attribute name is valid, and
    the default value used for each attribute if it is not included in
    <attrib_list>.

      +-------------------------------------+-------------------------+-------------------------+---------------+
      | Attribute                           | Description             | Valid                   | Default Value |
      |                                     |                         | <target>s               |               |
      +-------------------------------------+-------------------------+-------------------------+---------------+
      | EGL_METAL_TEXTURE_ARRAY_SLICE_ANGLE | Select which 2d texture | EGL_METAL_TEXTURE_ANGLE | 0             |
      |                                     | array slice to use      |                         |               |
      +-------------------------------------+-------------------------+-------------------------+---------------+
      | EGL_TEXTURE_INTERNAL_FORMAT_ANGLE   | Override the intended   | EGL_METAL_TEXTURE_ANGLE | GL_NONE       |
      |                                     | internal format         |                         |               |
      +-------------------------------------+-------------------------+-------------------------+---------------+
       Table bbb.  Legal attributes for eglCreateImageKHR <attrib_list> parameter

    If <target> is EGL_METAL_TEXTURE_ANGLE, <dpy> must be a valid display, <ctx>
    must be EGL_NO_CONTEXT, <buffer> must be a pointer to a valid MTLTexture
    object (cast into the type EGLClientBuffer), and attributes are ignored.
    The width and height of the pbuffer are determined by the width and height
    of <buffer>."

    If EGL_METAL_TEXTURE_ARRAY_SLICE_ANGLE is specified, it is used to access
    the specified array slice of the texture array <buffer>. In case the <target>
    MTLTexture textureType property is MTLTextureType2DArray and arrayLength
    property is smaller or equal to the value, EGL_BAD_ATTRIBUTE error
    is generated. In case the target MTLTexture textureType property is not
    MTLTextureType2DArray, value other than 0 generates EGL_BAD_ATTRIBUTE.

    If EGL_TEXTURE_INTERNAL_FORMAT_ANGLE is specified, it is used to interpret
    <buffer> according to the provided internal format. If the MTLPixelFormat for
    the internal format is incompatible with that of the texture <buffer>, an
    EGL_BAD_PARAMETER error is generated.

    If the EGL_ANGLE_device_metal extension is present, the provided Metal texture
    object must have been created by the same Metal device queried from the
    display. If these requirements are not met, an EGL_BAD_PARAMETER error is
    generated."

Revision History

    Version 1, 2020-07-19 - First draft
    Version 2, 2024-02-12 - Add EGL_METAL_TEXTURE_ARRAY_SLICE_ANGLE
    Version 3, 2024-02-20 - Add EGL_TEXTURE_INTERNAL_FORMAT_ANGLE