Name Strings

SPV_AMD_shader_early_and_late_fragment_tests

Contact

To report problems with this extension, please open a new issue at:

https://github.com/KhronosGroup/SPIRV-Registry

Contributors

  • Tobias Hector, AMD

Notice

Copyright (c) 2021 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html

Status

  • Draft

Version

Last Modified Date

2021-11-05

Revision

1

Dependencies

This extension is written against the SPIR-V Specification, Version 1.5 Revision 5.

This extension requires SPIR-V 1.0.

Overview

This extension adds the EarlyAndLateFragmentTestsAMD Execution Mode, which enables both early and late fragment tests in some circumstances.

Additionally, it adds execution modes describing how the shader stencil value is written, allowing stencil writes to be used with this new mode.

Extension Name

To use this extension within a SPIR-V module, the following OpExtension must be present in the module:

OpExtension "SPV_AMD_shader_early_and_late_fragment_tests"

Modifications to the SPIR-V Specification, Version 1.5

Capabilities

Modify Section 3.6, "Execution Mode", adding the following row to the table:

Execution mode Extra Operands Enabling Capabilities

5017

EarlyAndLateFragmentTestsAMD
Fragment tests can be performed both before and after fragment shader execution, with latter tests taking values written to FragDepth and FragStencilRefEXT into account. Early tests are not guaranteed, late tests are.+
If neither of ExecutionModeDepthReplacing or ExecutionModeStencilRefReplacingEXT are specified, functions identically to EarlyFragmentTests.
If this and ExecutionModeStencilRefReplacingEXT are both specified, one of StencilRefGreaterAMD, StencilRefLessAMD, or StencilRefUnchangedAMD must also be specified.
If this and ExecutionModeDepthReplacing are both specified, one of DepthGreater, DepthLess, or DepthUnchanged must also be specified.

Only valid with the Fragment Execution Model.
See client API for detail on fragment operations.

Shader

5079

StencilRefUnchangedFrontAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is equal to the stencil reference value set for the front face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

5080

StencilRefGreaterFrontAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is greater than or equal to the stencil reference value set for the front face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

5081

StencilRefLessFrontAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is less than or equal to the stencil reference value set for the front face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

5082

StencilRefUnchangedBackAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is equal to the stencil reference value set for the back face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

5083

StencilRefGreaterBackAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is greater than or equal to the stencil reference value set for the back face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

5084

StencilRefLessBackAMD
Indicates that early per-fragment tests may assume that any FragStencilRefEXT built in-decorated value written by the shader is less than or equal to the stencil reference value set for the back face in the client API after masking. Late per-fragment tests will use the written value as normal.

Only valid with the Fragment Execution Model.
At most one of StencilRefGreaterAMD, StencilRefLessAMD, and StencilRefUnchangedAMD can be specified.

StencilExportEXT

Revision History

Rev Date Author Changes

1

2021-11-05

Tobias Hector

Initial extension.