Contact
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Aaron Hagan AaronHaganAMD
Other Extension Metadata
- Last Modified Date
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2017-08-16
- IP Status
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No known IP claims.
- Interactions and External Dependencies
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This extension provides API support for
GL_AMD_shader_fragment_mask
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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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Description
This extension provides efficient read access to the fragment mask in compressed multisampled color surfaces. The fragment mask is a lookup table that associates color samples with color fragment values.
From a shader, the fragment mask can be fetched with a call to
fragmentMaskFetchAMD, which returns a single uint where each
subsequent four bits specify the color fragment index corresponding to the
color sample, starting from the least significant bit.
For example, when eight color samples are used, the color fragment index for
color sample 0 will be in bits 0-3 of the fragment mask, for color sample 7
the index will be in bits 28-31.
The color fragment for a particular color sample may then be fetched with
the corresponding fragment mask value using the fragmentFetchAMD shader
function.
New Enum Constants
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VK_AMD_SHADER_FRAGMENT_MASK_EXTENSION_NAME -
VK_AMD_SHADER_FRAGMENT_MASK_SPEC_VERSION
Examples
This example shows a shader that queries the fragment mask from a multisampled compressed surface and uses it to query fragment values.
#version 450 core
#extension GL_AMD_shader_fragment_mask: enable
layout(binding = 0) uniform sampler2DMS s2DMS;
layout(binding = 1) uniform isampler2DMSArray is2DMSArray;
layout(binding = 2, input_attachment_index = 0) uniform usubpassInputMS usubpassMS;
layout(location = 0) out vec4 fragColor;
void main()
{
vec4 fragOne = vec4(0.0);
uint fragMask = fragmentMaskFetchAMD(s2DMS, ivec2(2, 3));
uint fragIndex = (fragMask & 0xF0) >> 4;
fragOne += fragmentFetchAMD(s2DMS, ivec2(2, 3), 1);
fragMask = fragmentMaskFetchAMD(is2DMSArray, ivec3(2, 3, 1));
fragIndex = (fragMask & 0xF0) >> 4;
fragOne += fragmentFetchAMD(is2DMSArray, ivec3(2, 3, 1), fragIndex);
fragMask = fragmentMaskFetchAMD(usubpassMS);
fragIndex = (fragMask & 0xF0) >> 4;
fragOne += fragmentFetchAMD(usubpassMS, fragIndex);
fragColor = fragOne;
}Document Notes
For more information, see the Vulkan Specification
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