Name

    AMD_shader_fragment_mask

Name Strings

    GL_AMD_shader_fragment_mask

Contact

    Aaron Hagan, AMD (aaron.hagan 'at' amd.com)

Contributors

    Aaron Hagan, AMD
    Timothy Lottes, AMD
    Daniel Rakos, AMD

Status

    Pending

Version

    Last Modified Date:         08/07/2017
    Author Revision:            2

Number

    TBD

Dependencies

    This extension is written against the OpenGL Shading Language
    Specification, Version 4.50.

Overview

    This extension introduces new GLSL built-in functions enabling more
    efficient read access to fragment mask compressed multisampled color
    images. Implementations supporting this extension can avoid storing
    identical sample color values inside a single pixel. This is achieved
    by introducing the concept of color fragments and fragment masks.

    Color fragments are storage units inside a single pixel of a multisampled
    color image that can hold a unique color value. Each pixel then has a
    fragment mask which contains per sample indices that map a given color
    sample to a particular color fragment.

    This extension enables fetching the fragment mask and individual color
    fragments from a multisampled color image.

IP Status

    None.

New Procedures and Functions

    None.

New Tokens

    None.

Modifications to the OpenGL Shading Language Specification, Version 4.50

    Including the following line in a shader can be used to control the
    language features described in this extension:

      #extension GL_AMD_shader_fmask : <behavior>

    where <behavior> is as specified in section 3.3.

    New preprocessor #defines are added to the OpenGL Shading Language:

      #define GL_AMD_shader_fragement_mask 1

Additions to Chapter 8 of the OpenGL Shading Language (GLSL) Specification,
version 4.30 (Built-in functions)

    Add to the table of functions 8.9.2, "Texel Lookup Functions", p. 164

    +-----------------------------------+-------------------------------------+
    | Syntax                            | Description                         |
    +-----------------------------------+-------------------------------------+
    | uint fragmentMaskFetchAMD(        | Returns the fragment mask from a    |
    |      gsampler2DMS sampler,        | multisampled color image. The       |
    |      ivec2        P)              | fragment mask is a single uint where|
    |                                   | each subsequent 4 bit specifies the |
    | uint fragmentMaskFetchAMD(        | color fragment index corresponding  |
    |      gsampler2DMSArray sampler,   | to the color sample, starting from  |
    |      ivec3             P)         | the least significant bit.          |
    |                                   |                                     |
    | uint fragmentMaskFetchAMD(        |                                     |
    |      gsubpassInputMS subpass)     |                                     |
    +-----------------------------------+-------------------------------------+
    | gvec4 fragmentFetchAMD(           | Fetches a color fragment with a     |
    |       gsampler2DMS sampler,       | correspoding fragment mask value.   |
    |       ivec2        P,             |                                     |
    |       uint         fragIndex)     |                                     |
    |                                   |                                     |
    | gvec4 fragmentFetchAMD(           |                                     |
    |       gsampler2DMSArray sampler,  |                                     |
    |       ivec3             P,        |                                     |
    |       uint              fragIndex)|                                     |
    |                                   |                                     |
    | gvec4 fragmentFetchAMD(           |                                     |
    |       gsubpassInputMS subpass,    |                                     |
    |       uint            fragIndex)  |                                     |
    +-----------------------------------+-------------------------------------+


Additions to the AGL/GLX/WGL Specifications

    None.

GLX Protocol

    None.

Errors

    None.

Issues


Revision History

    Rev.    Date      Author    Changes
    ----  ----------  --------  -----------------------------------------------
     2    08/07/2017  ahagan    Cleanup and prepared for posting.

     1    04/24/2017  ahagan    Initial draft.