1// Copyright (c) 2017-2020 Advanced Micro Devices, Inc. 2// 3// SPDX-License-Identifier: CC-BY-4.0 4 5include::{generated}/meta/{refprefix}VK_AMD_shader_fragment_mask.adoc[] 6 7=== Other Extension Metadata 8 9*Last Modified Date*:: 10 2017-08-16 11*IP Status*:: 12 No known IP claims. 13*Interactions and External Dependencies*:: 14 - This extension requires 15 {spirv}/AMD/SPV_AMD_shader_fragment_mask.html[`SPV_AMD_shader_fragment_mask`] 16 - This extension provides API support for 17 {GLSLregistry}/amd/GL_AMD_shader_fragment_mask.txt[`GL_AMD_shader_fragment_mask`] 18*Contributors*:: 19 - Aaron Hagan, AMD 20 - Daniel Rakos, AMD 21 - Timothy Lottes, AMD 22 23=== Description 24 25This extension provides efficient read access to the fragment mask in 26compressed multisampled color surfaces. 27The fragment mask is a lookup table that associates color samples with color 28fragment values. 29 30From a shader, the fragment mask can be fetched with a call to 31code:fragmentMaskFetchAMD, which returns a single code:uint where each 32subsequent four bits specify the color fragment index corresponding to the 33color sample, starting from the least significant bit. 34For example, when eight color samples are used, the color fragment index for 35color sample 0 will be in bits 0-3 of the fragment mask, for color sample 7 36the index will be in bits 28-31. 37 38The color fragment for a particular color sample may then be fetched with 39the corresponding fragment mask value using the code:fragmentFetchAMD shader 40function. 41 42include::{generated}/interfaces/VK_AMD_shader_fragment_mask.adoc[] 43 44=== New SPIR-V Capabilities 45 46 * <<spirvenv-capabilities-table-FragmentMaskAMD, code:FragmentMaskAMD>> 47 48=== Examples 49 50This example shows a shader that queries the fragment mask from a 51multisampled compressed surface and uses it to query fragment values. 52 53[source,c++] 54---------------------------------------- 55#version 450 core 56 57#extension GL_AMD_shader_fragment_mask: enable 58 59layout(binding = 0) uniform sampler2DMS s2DMS; 60layout(binding = 1) uniform isampler2DMSArray is2DMSArray; 61 62layout(binding = 2, input_attachment_index = 0) uniform usubpassInputMS usubpassMS; 63 64layout(location = 0) out vec4 fragColor; 65 66void main() 67{ 68 vec4 fragOne = vec4(0.0); 69 70 uint fragMask = fragmentMaskFetchAMD(s2DMS, ivec2(2, 3)); 71 uint fragIndex = (fragMask & 0xF0) >> 4; 72 fragOne += fragmentFetchAMD(s2DMS, ivec2(2, 3), 1); 73 74 fragMask = fragmentMaskFetchAMD(is2DMSArray, ivec3(2, 3, 1)); 75 fragIndex = (fragMask & 0xF0) >> 4; 76 fragOne += fragmentFetchAMD(is2DMSArray, ivec3(2, 3, 1), fragIndex); 77 78 fragMask = fragmentMaskFetchAMD(usubpassMS); 79 fragIndex = (fragMask & 0xF0) >> 4; 80 fragOne += fragmentFetchAMD(usubpassMS, fragIndex); 81 82 fragColor = fragOne; 83} 84---------------------------------------- 85 86=== Version History 87 88 * Revision 1, 2017-08-16 (Aaron Hagan) 89 ** Initial draft 90