kc3-lang/angle/extensions/ANGLE_texture_multisample_array.txt

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• Author : Olli Etuaho
  Date : 2018-08-23 11:16:15
  Hash : 4285647b
  Message : Draft ANGLE_texture_multisample_array spec This is needed for antialiased multiview rendering. The extension is written against OpenGL ES 3.1. To add support for it in OpenGL ES 3.0, an extension for exposing non-array multisample textures will also be required (ANGLE_texture_multisample). This has been previously proposed though not yet submitted to ANGLE. The extension spec provides robustness guarantees for sampling multisample textures. It still needs to be tested whether native implementations follow these guarantees or if the spec needs to be adjusted to allow for clamping coordinates. The native KHR_robust_buffer_access_behavior is not very explicit about whether the texel fetch robustness applies also to multisample textures. BUG=angleproject:2775 Change-Id: I1bd721008a10bee29f8e2e06edca19370a9932a7 Reviewed-on: https://chromium-review.googlesource.com/1186336 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Kenneth Russell <kbr@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

• extensions/ANGLE_texture_multisample_array.txt

• Name
  
      ANGLE_texture_multisample_array
  
  Name Strings
  
      GL_ANGLE_texture_multisample_array
  
  Contributors
  
      Olli Etuaho, NVIDIA Corporation
      Contributors to OpenGL ES 3.2, on which this extension is based
  
  Contact
  
      Olli Etuaho (oetuaho 'at' nvidia.com)
  
  Status
  
      Incomplete
  
  Version
  
      Last Modified Date: August 23, 2018
      Author Revision: 1
  
  Number
  
      OpenGL ES Extension XX
  
  Dependencies
  
      OpenGL ES 3.0 and the ANGLE_texture_multisample extension, or OpenGL ES
      3.1 is required.
  
      Written against the OpenGL ES 3.1 specification.
  
  Overview
  
      This extension provides support for a new type of texture -
      two-dimensional multisample array texture - as well as mechanisms to
      allocate storage and attach such textures to FBOs for rendering,
      to support such a texture in a shader, to fetch a specific sample
      from such a texture in a shader, and to query the dimensions of
      such a texture in a shader.
  
      This extension is based on functionality in the OpenGL ES 3.2
      specification.
  
  IP Status
  
      No known IP claims.
  
  New Tokens
  
      Accepted by the <target> parameter of BindTexture,
      TexStorage3DMultisampleANGLE, GetInternalformativ, TexParameter{if}*,
      GetTexParameter{if}v, GetTexLevelParameter{if}vANGLE and
      by the <textarget> parameter of FramebufferTexture2D:
  
          TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE                0x9102
  
      Accepted by the <pname> parameter of GetIntegerv:
  
          TEXTURE_BINDING_2D_MULTISAMPLE_ARRAY_ANGLE        0x9105
  
      Returned by the <type> parameter of GetActiveUniform:
  
          SAMPLER_2D_MULTISAMPLE_ARRAY_ANGLE                0x910B
          INT_SAMPLER_2D_MULTISAMPLE_ARRAY_ANGLE            0x910C
          UNSIGNED_INT_SAMPLER_2D_MULTISAMPLE_ARRAY_ANGLE   0x910D
  
  New Procedures and Functions
  
      void TexStorage3DMultisampleANGLE(enum target,
                                        sizei samples,
                                        enum sizedinternalformat,
                                        sizei width,
                                        sizei height,
                                        sizei depth,
                                        boolean fixedsamplelocations);
  
  Additions to Chapter 8 of the OpenGL ES 3.1 Specification (Textures and Samplers)
  
      Modify Section 8.8, "Multisample Textures".
  
      (first paragraph of section 8.8)
  
      In addition to the texture types described in previous sections, two
      additional types of textures are supported. A multisample texture is
      similar to a two-dimensional or two-dimensional array texture,
      except it contains multiple samples per texel. Multisample textures do
      not have multiple image levels, and are immutable.
  
      (insert after description of TexStorage2DMultisampleANGLE)
  
      The command
  
          void TexStorage3DMultisampleANGLE(enum target, sizei samples,
                                            int sizedinternalformat,
                                            sizei width, sizei height, sizei depth,
                                            boolean fixedsamplelocations);
  
      establishes the data storage, format, dimensions, and number of
      samples of a multisample texture array's image. <target> must be
      TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE. <width>, <height> and <depth> are the
      dimensions in texels of the texture.
  
      Upon success, TexStorage3DMultisampleANGLE deletes any existing image
      for <target> and the contents of texels are undefined. The values of
      TEXTURE_WIDTH, TEXTURE_HEIGHT, TEXTURE_DEPTH, TEXTURE_SAMPLES_ANGLE,
      TEXTURE_INTERNAL_FORMAT and TEXTURE_FIXED_SAMPLE_LOCATIONS_ANGLE are
      set to <width>, <height>, the actual number of samples allocated,
      <sizedinternalformat>, and <fixedsamplelocations> respectively.
  
      (modify errors in Section 8.8)
  
      An INVALID_ENUM error is generated if target is not
      TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE in case of TexStorage3DMultisampleANGLE,
      or TEXTURE_2D_MULTISAMPLE_ANGLE in case of TexStorage2DMultisampleANGLE.
      An INVALID_VALUE is generated if <width>, <height> or <depth> is less than 1.
  
      (insert into errors is Section 8.8)
  
      An INVALID_VALUE error is generated by TexStorage3DMultisample if depth is
      greater than the value of MAX_ARRAY_TEXTURE_LAYERS.
  
      Modify Section 8.9, "Texture Parameters":
  
      Add TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE to the texture targets accepted by
      TexParameter*.
  
      (add to the end of Section 8.9)
  
      An INVALID_ENUM is generated if <target> is
      TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE and <pname> is any sampler state from
      table 20.11. An INVALID_OPERATION error is generated if <target> is
      TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE, and <pname> TEXTURE_BASE_LEVEL is set
      to any value other than zero.
  
      Modify Section 8.10.2, "Texture Parameter Queries":
  
      (modify the paragraph describing the <target> parameter of
      GetTexParameter*)
  
      <target> may be one of TEXTURE_2D, TEXTURE_3D, TEXTURE_2D_ARRAY,
      TEXTURE_CUBE_MAP, TEXTURE_2D_MULTISAMPLE_ANGLE, or
      TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE, indicating the currently bound
      two-dimensional, three-dimensional, two-dimensional array, cube map,
      two-dimensional multisample, or two-dimensional multisample array
      texture object, respectively.
  
      Modify Section 8.10.3, "Texture Level Parameter Queries"
  
      (modify the paragraph describing the <target> parameter of
      GetTexLevelParameter*)
  
      <target> may be one of TEXTURE_2D, TEXTURE_3D, TEXTURE_2D_ARRAY, one of
      the cube map face targets from table 8.21, TEXTURE_2D_MULTISAMPLE_ANGLE,
      or TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE indicating the two- or
      three-dimensional texture, two-dimensional array texture, one of the six
      distinct 2D images making up the cube map texture object, two-dimensional
      multisample texture or two-dimensional multisample array texture. Otherwise
      an INVALID_ENUM is generated.
  
  Additions to Chapter 9 of the OpenGL ES 3.1 Specification (Framebuffers and
  Framebuffer Objects)
  
      Modify section 9.2.8 "Attaching Texture Images to a Framebuffer".
  
      (modify description of FrameBufferTextureLayer p. 223)
  
      The command
  
          void FramebufferTextureLayer(enum target, enum attachment,
                                       uint texture, int level, int layer);
  
      operates similarly to FramebufferTexture2D, except that it attaches a
      single layer of a three-dimensional texture, two-dimensional array
      texture or two-dimensional multisample array texture level.
  
      The error INVALID_OPERATION is generated if texture is non-zero
      and is not the name of a three-dimensional texture, two-dimensional
      array texture or or two-dimensional multisample array texture.
  
      (insert into description of FrameBufferTextureLayer p. 224)
  
      If <texture> identifies a two-dimensional multisample array texture,
      then <level> must be zero. Otherwise, an INVALID_VALUE error is
      generated.
  
  Additions to Chapter 11 of the OpenGL ES 3.1 Specification (Programmable Vertex Processing)
  
      Modify Section 11.1.3.3 "Multisample Texel Fetches":
  
      (modify the paragraph before the list of conditions for undefined results)
  
      If the context was created with robust buffer access enabled, the result
      of the texel fetch in the following cases is zero. If robust buffer
      access is not enabled, the result of the texel fetch is undefined in
      each case:
  
  Additions to Chapter 19 of the OpenGL ES 3.1 Specification (Context State Queries)
  
      Modify Section 19.3, "Internal Format Queries":
  
      Add target TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE to table 19.1.
  
  Additions to the AGL/EGL/GLX/WGL Specifications
  
      None
  
  Additions to the OpenGL ES Shading Language Specification, Version 3.10.
  
      Including the following line in a shader can be used to control the
      language featured described in this extension:
  
        #extension GL_ANGLE_texture_multisample_array : <behavior>
  
      where <behavior> is as specified in section 3.5.
  
      A new preprocessor #define is added to the OpenGL ES Shading Language:
  
        #define GL_ANGLE_texture_multisample_array 1
  
      Add to section 3.8 "Keywords":
  
      The following new sampler types are added:
  
        sampler2DMSArray, isampler2DMSArray, usampler2DMSArray,
  
      Add to section 4.1 "Basic Types":
  
      Add the following sampler type to the "Floating Point Sampler
      Types (opaque)" table:
  
        sampler2DMSArray    handle for accessing a 2D multisample array texture
  
      Add the following sampler type to the "Unsigned Integer Sampler
      Types (opaque)" table:
  
        usampler2DMSArray    handle for accessing an unsigned integer 2D
                             multisample array texture
  
      Add the following sampler type to the "Integer Sampler Types" table:
  
        isampler2DMSArray    handle for accessing an integer 2D
                             multisample array texture
  
      Add to section 8.8 "Texture Lookup Functions":
  
      Add new functions to the set of allowed texture lookup functions:
  
      Syntax:
  
        gvec4 texelFetch(gsampler2DMSArray sampler, ivec3 P, int sample)
  
      Description:
  
        Use integer texture coordinate <P> to lookup a single sample
        <sample> on the texture bound to <sampler> as described in the OpenGL
        ES specification section 11.1.3.3 "Multisample Texel Fetches".
  
      Syntax:
  
        ivec3 textureSize(gsampler2DMSArray sampler)
  
      Description:
  
        Returns the dimensions, width, height and depth of level 0 for the
        texture bound to <sampler>, as described in  the OpenGL ES
        specification section 11.1.3.4 "Texture Queries".
  
  Errors
  
      The error INVALID_ENUM is generated by TexStorage3DMultisampleANGLE if
      <target> is not TEXTURE_2D_MULTISAMPLE_ARRAY_ANGLE.
  
      The error INVALID_OPERATION is generated by TexStorage3DMultisampleANGLE
      if zero is bound to <target>.
  
      The error INVALID_VALUE is generated by TexStorage3DMultisampleANGLE if
      <width> or <height> is less than 1 or greater than the value of
      MAX_TEXTURE_SIZE.
  
      The error INVALID_VALUE is generated by TexStorage3DMultisampleANGLE if
      <depth> is less than 1 or greater than the value of
      MAX_ARRAY_TEXTURE_LAYERS.
  
      The error INVALID_VALUE is generated by TexStorage3DMultisampleANGLE if
      <samples> is zero.
  
      The error INVALID_ENUM is generated by TexStorage3DMultisampleANGLE if
      <sizedinternalformat> is not color-renderable, depth-renderable, or
      stencil-renderable.
  
      The error INVALID_ENUM is generated by TexStorage3DMultisampleANGLE if
      <internalformat> is one of the unsized base internal formats listed in
      table 8.11.
  
      The error INVALID_OPERATION is generated by TexStorage3DMultisampleANGLE
      if <samples> is greater than the maximum number of samples supported for
      this <target> and <sizedinternalformat>, The maximum number of samples
      supported can be determined by calling GetInternalformativ with a <pname>
      of SAMPLES.
  
      The error INVALID_OPERATION is generated by TexStorage3DMultisampleANGLE
      if the value of TEXTURE_IMMUTABLE_FORMAT for the texture currently bound
      to <target> on the active texture unit is TRUE.
  
      The error OUT_OF_MEMORY is generated by TexStorage3DMultisampleANGLE
      if the GL is unable to create a texture image of the requested size.
  
      The error INVALID_VALUE is generated by FramebufferTextureLayer if
      <texture> identifies a two-dimensional multisample array texture, and
      <level> is not zero.
  
  Issues
  
      None