// Copyright 2018-2021 The Khronos Group Inc.
//
// SPDX-License-Identifier: CC-BY-4.0

include::{generated}/meta/{refprefix}VK_EXT_fragment_density_map.txt[]

=== Other Extension Metadata

*Last Modified Date*::
    2021-09-30
*Interactions and External Dependencies*::
  - This extension requires
    {spirv}/EXT/SPV_EXT_fragment_invocation_density.html[`SPV_EXT_fragment_invocation_density`]
*Contributors*::
  - Matthew Netsch, Qualcomm Technologies, Inc.
  - Robert VanReenen, Qualcomm Technologies, Inc.
  - Jonathan Wicks, Qualcomm Technologies, Inc.
  - Tate Hornbeck, Qualcomm Technologies, Inc.
  - Sam Holmes, Qualcomm Technologies, Inc.
  - Jeff Leger, Qualcomm Technologies, Inc.
  - Jan-Harald Fredriksen, ARM
  - Jeff Bolz, NVIDIA
  - Pat Brown, NVIDIA
  - Daniel Rakos, AMD
  - Piers Daniell, NVIDIA

=== Description

This extension allows an application to specify areas of the render target
where the fragment shader may be invoked fewer times.
These fragments are broadcasted out to multiple pixels to cover the render
target.

The primary use of this extension is to reduce workloads in areas where
lower quality may not be perceived such as the distorted edges of a lens or
the periphery of a user's gaze.

include::{generated}/interfaces/VK_EXT_fragment_density_map.txt[]

=== New or Modified Built-In Variables

  * <<interfaces-builtin-variables-fraginvocationcount,code:FragInvocationCountEXT>>
  * <<interfaces-builtin-variables-fragsize,code:FragSizeEXT>>

=== New SPIR-V Capabilities

  * <<spirvenv-capabilities-table-FragmentDensityEXT,FragmentDensityEXT>>

=== Version History

  * Revision 1, 2018-09-25 (Matthew Netsch)
    - Initial version
  * Revision 2, 2021-09-30 (Jon Leech)
    - Add interaction with `apiext:VK_KHR_format_feature_flags2` to `vk.xml`