include::meta/VK_EXT_shader_demote_to_helper_invocation.txt[]

*Last Modified Date*::
    2019-06-01
*IP Status*::
    No known IP claims.
*Contributors*::
  - Jeff Bolz, NVIDIA

This extension adds Vulkan support for the
{spirv}/EXT/SPV_EXT_demote_to_helper_invocation.html[`SPV_EXT_demote_to_helper_invocation`]
SPIR-V extension.
That SPIR-V extension provides a new instruction
code:OpDemoteToHelperInvocationEXT allowing shaders to "demote" a fragment
shader invocation to behave like a helper invocation for its duration.
The demoted invocation will have no further side effects and will not output
to the framebuffer, but remains active and can participate in computing
derivatives and in subgroup operations.
This is a better match for the "discard" instruction in HLSL.

=== New Object Types

None.

=== New Enum Constants

  * Extending elink:VkStructureType:
  ** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SHADER_DEMOTE_TO_HELPER_INVOCATION_FEATURES_EXT

=== New Enums

None.

=== New Structures

  * slink:VkPhysicalDeviceShaderDemoteToHelperInvocationFeaturesEXT

=== New Functions

None.

=== New SPIR-V Capability

  * <<spirvenv-capabilities-table-demote,DemoteToHelperInvocationEXT>>

=== Issues

None.

=== Examples

None.

=== Version History

 * Revision 1, 2019-06-01 (Jeff Bolz)
   - Initial draft