Name Strings
SPV_AMD_shader_fragment_mask
Contact
To report problems with this extension, please open a new issue at:
Contributors
-
Aaron Hagan, AMD
-
Daniel Rakos, AMD
-
Rex Xu, AMD
Notice
Copyright (c) 2017 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html
Status
Draft.
Version
Modified Date: August 16, 2017 Revision: 1
Dependencies
This extension is written against Revision 1 of the version 1.12 of the SPIR-V Specification.
The extension is written against Revision 1 of the OpenGL extension AMD_shader_fragment_mask.
Overview
This extension is written to provide the functionality of the AMD_shader_fragment_mask, OpenGL Shading Language Specification extension, for SPIR-V.
This extension introduces two core instructions to SPIR-V that enable fetching the fragment mask of compressed multisampled color surfaces, and an instruction for sampling the surface with the fragment mask.
Extension Name
To use this extension within a SPIR-V module, the following OpExtension must be present in the module:
OpExtension "SPV_AMD_shader_fragment_mask"
New Capabilities
This extension introduces a new capability:
FragmentMaskAMD = 5010
New Instructions
This extension adds the following core instructions
OpFragmentMaskFetchAMD = 5011 OpFragmentFetchAMD = 5012
Modifications to the SPIR-V Specification, Version 1.1
Modify Section 3.32.10, Image Instructions
Add the following items to the instruction sections.
OpFragmentMaskFetchAMD
The fragment mask can be fetched from a compressed multisampled color surface with a call to fragmentMaskFetchAMD in the shader. The returned value is a single unsigned integer where each subsequent 4 bit specifies the color fragment index corresponding to the color sample, starting from the least significant bit.
Result Type must be a 32-bit unsigned integer type scalar.
Image must be an object whose type is OpTypeImage with MS of 1. Dim must be 2D or SubpassData
Coordinate is an integer scalar or vector containing (u[, v] … [, array layer]) as needed by the definition of Sampled Image. When the Image Dim operand is SubpassData, Coordinate is relative to the current fragment location. That is, the integer value (rounded down) of the current fragment’s window-relative (x, y) coordinate is added to (u, v).
5 |
5011 |
<id> Result Type |
Result <id> |
<id> Image |
<id> Coordinate |
OpFragmentFetchAMD
The color fragment for a particular sample can be fetched using the coorespondng fragment mask index and calling fragmentFetchAMD.
Result Type must be a vector of four components of floating-point type or integer type. Its components must be the same as Sampled Type of the underlying OpTypeImage (unless that underlying Sampled Type isOpTypeVoid).
Image must be an object whose type is OpTypeImage with MS of 1. Dim must be 2D or SubpassData
Coordinate is an integer scalar or vector containing (u[, v] … [, array layer]) as needed by the definition of Sampled Image. When the Image Dim operand is SubpassData, Coordinate is relative to the current fragment location. That is, the integer value (rounded down) of the current fragment’s window-relative (x, y) coordinate is added to (u, v).
Fragment Index fragment mask index used to sample the color fragment
6 |
5012 |
<id> Result Type |
Result <id> |
<id> Image |
<id> Coordinate |
<id> Fragment Index |
Validation Rules
None.
Issues
None
Revision History
| Rev | Date | Author | Changes |
|---|---|---|---|
1 |
August 16, 2017 |
Aaron Hagan |
Initial revision based on SPV_AMD_shader_fragment_mask. |