100 lines
2.6 KiB
Plaintext
100 lines
2.6 KiB
Plaintext
include::meta/VK_AMD_shader_fragment_mask.txt[]
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*Last Modified Date*::
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2017-08-16
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*IP Status*::
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No known IP claims.
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*Dependencies*::
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- Requires the
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https://www.khronos.org/registry/spir-v/extensions/AMD/SPV_AMD_fragment_mask.html[+SPV_AMD_fragment_mask+]
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SPIR-V extension.
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*Contributors*::
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- Aaron Hagan, AMD
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- Daniel Rakos, AMD
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- Timothy Lottes, AMD
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This extension provides efficient read access to the fragment mask in
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compressed multisampled color surfaces.
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The fragment mask is a lookup table that associates color samples with color
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fragment values.
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The fragment mask can be fetched with a call to code:fragmentMaskFetchAMD
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from a shader, which returns a single code:uint where each subsequent 4 bit
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specifies the color fragment index corresponding to the color sample,
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starting from the least significant bit.
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For example, when 8 color samples are used, the color fragment index for
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color sample 0 will be in bits 0-3 of the fragment mask, for color sample 7
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the index will be in bits 28-31.
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The color fragment for a particular color sample may then be fetched with
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the corresponding fragment mask value using the code:fragmentFetchAMD shader
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function.
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=== New Object Types
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None.
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=== New Enum Constants
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None.
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=== New Enums
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None.
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=== New SPIR-V Capabilities
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* <<spirvenv-capabilities-table-shaderfragmentmaskamd,
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code:ShaderFragmentMaskAMD>>
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=== New Structures
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None.
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=== New Functions
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None.
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=== Examples
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This example shows a shader that queries the fragment mask from a
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multisampled compressed surface and uses it to query fragment values.
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[source,c++]
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----------------------------------------
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#version 450 core
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#extension GL_AMD_shader_fragment_mask: enable
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layout(binding = 0) uniform sampler2DMS s2DMS;
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layout(binding = 1) uniform isampler2DMSArray is2DMSArray;
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layout(binding = 2, input_attachment_index = 0) uniform usubpassInputMS usubpassMS;
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layout(location = 0) out vec4 fragColor;
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void main()
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{
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vec4 fragOne = vec4(0.0);
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uint fragMask = fragmentMaskFetchAMD(s2DMS, ivec2(2, 3));
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uint fragIndex = (fragMask & 0xF0) >> 4;
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fragOne += fragmentFetchAMD(s2DMS, ivec2(2, 3), 1);
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fragMask = fragmentMaskFetchAMD(is2DMSArray, ivec3(2, 3, 1));
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fragIndex = (fragMask & 0xF0) >> 4;
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fragOne += fragmentFetchAMD(is2DMSArray, ivec3(2, 3, 1), fragIndex);
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fragMask = fragmentMaskFetchAMD(usubpassMS);
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fragIndex = (fragMask & 0xF0) >> 4;
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fragOne += fragmentFetchAMD(usubpassMS, fragIndex);
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fragColor = fragOne;
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}
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----------------------------------------
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=== Version History
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* Revision 1, 2017-08-16 (Aaron Hagan)
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- Initial draft
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