The Tor Browser: gfx/angle/extensions/ANGLE_framebuffer_multisample.txt@b8a032363ba2 (annotated)

gfx/angle/extensions/ANGLE_framebuffer_multisample.txt@b8a032363ba2 (annotated)

gfx/angle/extensions/ANGLE_framebuffer_multisample.txt

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 Name
     ANGLE_framebuffer_multisample
 Name Strings
     GL_ANGLE_framebuffer_multisample
 Contributors
     Contributors to EXT_framebuffer_multisample
     Daniel Koch, TransGaming Inc.
     Shannon Woods, TransGaming Inc.
     Kenneth Russell, Google Inc.
     Vangelis Kokkevis, Google Inc.
 Contacts
     Daniel Koch, TransGaming Inc. (daniel 'at' transgaming 'dot' com)
 Status
     Implemented in ANGLE ES2
 Version
     Last Modified Date: Aug 6, 2010
     Author Revision: #3
 Number
     OpenGL ES Extension #84
 Dependencies
     Requires OpenGL ES 2.0.
     Requires GL_ANGLE_framebuffer_blit (or equivalent functionality).
     The extension is written against the OpenGL ES 2.0 specification.
     OES_texture_3D affects the definition of this extension.
 Overview
     This extension extends the framebuffer object framework to
     enable multisample rendering.
     The new operation RenderbufferStorageMultisampleANGLE() allocates
     storage for a renderbuffer object that can be used as a multisample
     buffer.  A multisample render buffer image differs from a
     single-sample render buffer image in that a multisample image has a
     number of SAMPLES that is greater than zero.  No method is provided
     for creating multisample texture images.
     All of the framebuffer-attachable images attached to a framebuffer
     object must have the same number of SAMPLES or else the framebuffer
     object is not "framebuffer complete".  If a framebuffer object with
     multisample attachments is "framebuffer complete", then the
     framebuffer object behaves as if SAMPLE_BUFFERS is one.
     The resolve operation is affected by calling
     BlitFramebufferANGLE (provided by the ANGLE_framebuffer_blit
     extension) where the source is a multisample application-created
     framebuffer object and the destination is a single-sample
     framebuffer object (either application-created or window-system
     provided).
 New Procedures and Functions
     void RenderbufferStorageMultisampleANGLE(
             enum target, sizei samples,
             enum internalformat,
             sizei width, sizei height);
 New Types
     None.
 New Tokens
     Accepted by the <pname> parameter of GetRenderbufferParameteriv:
         RENDERBUFFER_SAMPLES_ANGLE                  0x8CAB
     Returned by CheckFramebufferStatus:
         FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_ANGLE    0x8D56
     Accepted by the <pname> parameter of GetBooleanv, GetIntegerv,
     and GetFloatv:
         MAX_SAMPLES_ANGLE                           0x8D57
 Additions to Chapter 2 of the OpenGL ES 2.0 Specification (OpenGL Operation)
 Additions to Chapter 3 of the OpenGL ES 2.0 Specification (Rasterization)
     Add to the last paragraph of 3.7.2 (Alternate Texture Image Specification)
     (as modified by ANGLE_framebuffer_blit) the following:
     "Calling CopyTexSubImage3DOES, CopyTexImage2D or CopyTexSubImage2D will
     result in INVALID_OPERATION being generated if the object bound to
     READ_FRAMEBUFFER_BINDING_ANGLE is "framebuffer complete" and the value
     of SAMPLE_BUFFERS is greater than zero."
 Additions to Chapter 4 of the OpenGL ES 2.0 Specification (Per-Fragment
 Operations and the Framebuffer)
     Add to 4.3.1 (Reading Pixels), right before the subsection titled
     "Obtaining Pixels from the Framebuffer":
     "ReadPixels generates INVALID_OPERATION if READ_FRAMEBUFFER_BINDING_ANGLE
     (section 4.4) is non-zero, the read framebuffer is framebuffer
     complete, and the value of SAMPLE_BUFFERS for the read framebuffer
     is greater than zero."
     In 4.3.2 (Copying Pixels), add to the section describing BlitFramebuffer
     that was added by ANGLE_framebuffer_blit.
     "If SAMPLE_BUFFERS for the read framebuffer is greater than zero and
     SAMPLE_BUFFERS for the draw framebuffer is zero, the samples
     corresponding to each pixel location in the source are converted to
     a single sample before being written to the destination.
     If SAMPLE_BUFFERS for the draw framebuffer is greater than zero,
     no copy is performed and an INVALID_OPERATION error is generated.
     If SAMPLE_BUFFERS for the read framebuffer is greater than zero and
     <mask> includes DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT, no copy is
     performed and an INVALID_OPERATION error is generated.
     If SAMPLE_BUFFERS for the read framebuffer is greater than zero and
     the format of the read and draw framebuffers are not identical, no
     copy is performed and an INVALID_OPERATION error is generated.
     If SAMPLE_BUFFERS for the read framebuffer is greater than zero, the
     dimensions of the source and destination rectangles provided to
     BlitFramebufferANGLE must be identical and must specify the complete
     source and destination buffers, otherwise no copy is performed and
     an INVALID_OPERATION error is generated."
     Modification to 4.4.3 (Renderbuffer Objects)
     Add, just above the definition of RenderbufferStorage:
     "The command
         void RenderbufferStorageMultisampleANGLE(
             enum target, sizei samples,
             enum internalformat,
             sizei width, sizei height);
     establishes the data storage, format, dimensions, and number of
     samples of a renderbuffer object's image.  <target> must be
     RENDERBUFFER.  <internalformat> must be one of the color-renderable,
     depth-renderable, or stencil-renderable formats described in table 4.5.
     <width> and <height> are the dimensions in pixels of the renderbuffer.  If
     either <width> or <height> is greater than the value of
     MAX_RENDERBUFFER_SIZE, or if <samples> is greater than MAX_SAMPLES_ANGLE,
     then the error INVALID_VALUE is generated. If OpenGL ES is unable to
     create a data store of the requested size, the error OUT_OF_MEMORY
     is generated.
     Upon success, RenderbufferStorageMultisampleANGLE deletes any existing
     data store for the renderbuffer image and the contents of the data
     store after calling RenderbufferStorageMultisampleANGLE are undefined.
     RENDERBUFFER_WIDTH is set to <width>, RENDERBUFFER_HEIGHT is
     set to <height>, and RENDERBUFFER_INTERNAL_FORMAT is set to
     <internalformat>.
     If <samples> is zero, then RENDERBUFFER_SAMPLES_ANGLE is set to zero.
     Otherwise <samples> represents a request for a desired minimum
     number of samples. Since different implementations may support
     different sample counts for multisampled rendering, the actual
     number of samples allocated for the renderbuffer image is
     implementation dependent.  However, the resulting value for
     RENDERBUFFER_SAMPLES_ANGLE is guaranteed to be greater than or equal
     to <samples> and no more than the next larger sample count supported
     by the implementation.
     An OpenGL ES implementation may vary its allocation of internal component
     resolution based on any RenderbufferStorageMultisampleANGLE parameter (except
     target), but the allocation and chosen internal format must not be a
     function of any other state and cannot be changed once they are
     established. The actual resolution in bits of each component of the
     allocated image can be queried with GetRenderbufferParameteriv."
     Modify the definiton of RenderbufferStorage as follows:
     "The command
         void RenderbufferStorage(enum target, enum internalformat,
                                     sizei width, sizei height);
      is equivalent to calling RenderbufferStorageMultisampleANGLE with
      <samples> equal to zero."
     In section 4.4.5 (Framebuffer Completeness) in the subsection
     titled "Framebuffer Completeness" add an entry to the bullet list:
     * The value of RENDERBUFFER_SAMPLES_ANGLE is the same for all attached
       images.
       { FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_ANGLE }
     Also add a paragraph to the end of the section after the definition
     of CheckFramebufferStatus:
     "The values of SAMPLE_BUFFERS and SAMPLES are derived from the
     attachments of the currently bound framebuffer object.  If the
     current DRAW_FRAMEBUFFER_BINDING_ANGLE is not "framebuffer complete",
     then both SAMPLE_BUFFERS and SAMPLES are undefined.  Otherwise,
     SAMPLES is equal to the value of RENDERBUFFER_SAMPLES_ANGLE for the
     attached images (which all must have the same value for
     RENDERBUFFER_SAMPLES_ANGLE).  Further, SAMPLE_BUFFERS is one if
     SAMPLES is non-zero.  Otherwise, SAMPLE_BUFFERS is zero.
 Additions to Chapter 5 of the OpenGL ES 2.0 Specification (Special Functions)
 Additions to Chapter 6 of the OpenGL ES 2.0 Specification (State and State
 Requests)
     In section 6.1.3 (Enumeraged Queries), modify the third paragraph
     of the description of GetRenderbufferParameteriv as follows:
     "Upon successful return from GetRenderbufferParameteriv, if
     <pname> is RENDERBUFFER_WIDTH, RENDERBUFFER_HEIGHT,
     RENDERBUFFER_INTERNAL_FORMAT, or RENDERBUFFER_SAMPLES_ANGLE, then <params>
     will contain the width in pixels, height in pixels, internal format, or
     number of samples, respectively, of the image of the renderbuffer
     currently bound to <target>."
 Dependencies on ANGLE_framebuffer_blit
     ANGLE_framebuffer_blit is required.  Technically, ANGLE_framebuffer_blit
     would not be required to support multisampled rendering, except for
     the fact that it provides the only method of doing a multisample
     resovle from a multisample renderbuffer.
 Dependencies on OES_texture_3D
     On an OpenGL ES implementation, in the absense of OES_texture_3D,
     omit references to CopyTexSubImage3DOES.
 Errors
     The error INVALID_OPERATION is generated if ReadPixels or
     CopyTex{Sub}Image* is called while READ_FRAMEBUFFER_BINDING_ANGLE
     is non-zero, the read framebuffer is framebuffer complete, and the
     value of SAMPLE_BUFFERS for the read framebuffer is greater than
     zero.
     If both the draw and read framebuffers are framebuffer complete and
     the draw framebuffer has a value of SAMPLE_BUFFERS that is greater
     than zero, then the error INVALID_OPERATION is generated if
     BlitFramebufferANGLE is called.
     If both the draw and read framebuffers are framebuffer complete and
     the read framebuffer has a value of SAMPLE_BUFFERS that is greater
     than zero, the error INVALID_OPERATION is generated if
     BlitFramebufferANGLE is called and any of the following conditions
     are true:
      - <mask> includes DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT.
      - the source or destination rectangles do not specify the entire
        source or destination buffer.
     If both the draw and read framebuffers are framebuffer complete and
     either has a value of SAMPLE_BUFFERS that is greater than zero, then
     the error INVALID_OPERATION is generated if BlitFramebufferANGLE is
     called and the formats of the draw and read framebuffers are not
     identical.
     If either the draw or read framebuffer is framebuffer complete and
     has a value of SAMPLE_BUFFERS that is greater than zero, then the
     error INVALID_OPERATION is generated if BlitFramebufferANGLE is called
     and the specified source and destination dimensions are not
     identical.
     If RenderbufferStorageMultisampleANGLE is called with <target> not
     equal to RENDERBUFFER, the error INVALID_ENUM is generated.
     If RenderbufferStorageMultisampleANGLE is called with an
     <internalformat> that is not listed as one of the color-, depth-
     or stencil-renderable formats in Table 4.5, then the error
     INVALID_ENUM is generated.
     If RenderbufferStorageMultisampleANGLE is called with <width> or
     <height> greater than MAX_RENDERBUFFER_SIZE, then the error
     INVALID_VALUE is generated.
     If RenderbufferStorageMultisampleANGLE is called with a value of
     <samples> that is greater than MAX_SAMPLES_ANGLE or less than zero,
     then the error INVALID_VALUE is generated.
     The error OUT_OF_MEMORY is generated when
     RenderbufferStorageMultisampleANGLE cannot create storage of the
     specified size.
 New State
     Add to table 6.22 (Renderbuffer State)
     Get Value                          Type    Get Command                 Initial Value  Description             Section
     -------------------------------    ------  --------------------------  -------------  --------------------    -------
     RENDERBUFFER_SAMPLES_ANGLE         Z+      GetRenderbufferParameteriv  0              number of samples       4.4.3
     Add to table 6.yy (Framebuffer Dependent Vaues) (added by
     ANGLE_framebuffer_blit), the following new framebuffer dependent state.
     Get Value          Type  Get Command     Minimum Value    Description             Section
     -----------------  ----  -----------     -------------    -------------------     -------
     MAX_SAMPLES_ANGLE  Z+    GetIntegerv     1                Maximum number of       4.4.3
                                                               samples supported
                                                               for multisampling
 Issues
     Issues from EXT_framebuffer_multisample have been removed.
 ) What should we call this extension?
        Resolved: ANGLE_framebuffer_blit.
        This extension is a result of a collaboration between Google and
        TransGaming for the open-source ANGLE project. Typically one would
        label a multi-vendor extension as EXT, but EXT_framebuffer_mulitsample
        is already the name for this on Desktop GL.  Additionally this
        isn't truely a multi-vendor extension because there is only one
        implementation of this.  We'll follow the example of the open-source
        MESA project which uses the project name for the vendor suffix.
 ) How does this extension differ from EXT_framebuffer_multisample?
        This is designed to be a proper subset of EXT_framebuffer_multisample
        functionality as applicable to OpenGL ES 2.0.
        Functionality that is unchanged:
         - creation of multisample renderbuffers.
         - whole buffer multi-sample->single-sample resolve.
         - no format conversions, stretching or flipping supported on multisample blits.
        Additional restrictions on BlitFramebufferANGLE:
         - multisample resolve is only supported on color buffers.
         - no blits to multisample destinations (no single->multi or multi-multi).
         - only entire buffers can be resolved.
 Revision History
     Revision 1, 2010/07/08
       - copied from revision 7 of EXT_framebuffer_multisample
       - removed language that was not relevant to ES2
       - rebase changes against the Open GL ES 2.0 specification
       - added ANGLE-specific restrictions
     Revision 2, 2010/07/19
       - fix missing error code
     Revision 3, 2010/08/06
       - add additional contributors, update implementation status
       - disallow negative samples

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gfx/angle/extensions/ANGLE_framebuffer_multisample.txt@b8a032363ba2 (annotated)

gfx/angle/extensions/ANGLE_framebuffer_multisample.txt