include::meta/VK_EXT_post_depth_coverage.txt[]

*Last Modified Date*::
    2017-07-17
*Interactions and External Dependencies*::
  - This extension requires the
    https://www.khronos.org/registry/spir-v/extensions/KHR/SPV_KHR_post_depth_coverage.html[+SPV_KHR_post_depth_coverage+]
    SPIR-V extension.
  - This extension requires
    https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_post_depth_coverage.txt[+GL_ARB_post_depth_coverage+]
    or
    https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_post_depth_coverage.txt[+GL_EXT_post_depth_coverage+]
    for GLSL-based source languages.
*Contributors*::
  - Jeff Bolz, NVIDIA

This extension adds support for the following SPIR-V extension in Vulkan:

  * +SPV_KHR_post_depth_coverage+

which allows the fragment shader to control whether values in the
code:SampleMask built-in input variable reflect the coverage after the
<<fragops-early,early per-fragment>> depth and stencil tests are applied.

This extension adds a new code:PostDepthCoverage execution mode under the
code:SampleMaskPostDepthCoverage capability.
When this mode is specified along with code:EarlyFragmentTests, the value of
an input variable decorated with the
<<interfaces-builtin-variables-samplemask, code:SampleMask>> built-in
reflects the coverage after the <<shaders-fragment-earlytest, early fragment
tests>> are applied.
Otherwise, it reflects the coverage before the depth and stencil tests.

When using GLSL source-based shading languages, the code:post_depth_coverage
layout qualifier from GL_ARB_post_depth_coverage or
GL_EXT_post_depth_coverage maps to the code:PostDepthCoverage execution
mode.

=== New Object Types

None.

=== New Enum Constants

None.

=== New Enums

None.

=== New Structures

None.

=== New Functions

None.

=== New Built-In Variables

None.

=== New Variable Decoration

None.

=== New SPIR-V Capabilities

  * <<spirvenv-capabilities-table-postdepthcoverage,SampleMaskPostDepthCoverage>>

=== Issues

None yet.

=== Version History

  * Revision 1, 2017-07-17 (Daniel Koch)
    - Internal revisions