1include::meta/VK_AMD_shader_fragment_mask.txt[] 2 3*Last Modified Date*:: 4 2017-08-16 5*IP Status*:: 6 No known IP claims. 7*Dependencies*:: 8 - Requires the 9 https://www.khronos.org/registry/spir-v/extensions/AMD/SPV_AMD_shader_fragment_mask.html[+SPV_AMD_shader_fragment_mask+] 10 SPIR-V extension. 11*Contributors*:: 12 - Aaron Hagan, AMD 13 - Daniel Rakos, AMD 14 - Timothy Lottes, AMD 15 16This extension provides efficient read access to the fragment mask in 17compressed multisampled color surfaces. 18The fragment mask is a lookup table that associates color samples with color 19fragment values. 20 21From a shader, the fragment mask can be fetched with a call to 22code:fragmentMaskFetchAMD, which returns a single code:uint where each 23subsequent four bits specify the color fragment index corresponding to the 24color sample, starting from the least significant bit. 25For example, when eight color samples are used, the color fragment index for 26color sample 0 will be in bits 0-3 of the fragment mask, for color sample 7 27the index will be in bits 28-31. 28 29The color fragment for a particular color sample may then be fetched with 30the corresponding fragment mask value using the code:fragmentFetchAMD shader 31function. 32 33=== New Object Types 34 35None. 36 37=== New Enum Constants 38 39None. 40 41=== New Enums 42 43None. 44 45=== New SPIR-V Capabilities 46 47 * <<spirvenv-capabilities-table-fragmentmaskamd, code:FragmentMaskAMD>> 48 49=== New Structures 50 51None. 52 53=== New Functions 54 55None. 56 57=== Examples 58 59This example shows a shader that queries the fragment mask from a 60multisampled compressed surface and uses it to query fragment values. 61 62[source,c++] 63---------------------------------------- 64#version 450 core 65 66#extension GL_AMD_shader_fragment_mask: enable 67 68layout(binding = 0) uniform sampler2DMS s2DMS; 69layout(binding = 1) uniform isampler2DMSArray is2DMSArray; 70 71layout(binding = 2, input_attachment_index = 0) uniform usubpassInputMS usubpassMS; 72 73layout(location = 0) out vec4 fragColor; 74 75void main() 76{ 77 vec4 fragOne = vec4(0.0); 78 79 uint fragMask = fragmentMaskFetchAMD(s2DMS, ivec2(2, 3)); 80 uint fragIndex = (fragMask & 0xF0) >> 4; 81 fragOne += fragmentFetchAMD(s2DMS, ivec2(2, 3), 1); 82 83 fragMask = fragmentMaskFetchAMD(is2DMSArray, ivec3(2, 3, 1)); 84 fragIndex = (fragMask & 0xF0) >> 4; 85 fragOne += fragmentFetchAMD(is2DMSArray, ivec3(2, 3, 1), fragIndex); 86 87 fragMask = fragmentMaskFetchAMD(usubpassMS); 88 fragIndex = (fragMask & 0xF0) >> 4; 89 fragOne += fragmentFetchAMD(usubpassMS, fragIndex); 90 91 fragColor = fragOne; 92} 93---------------------------------------- 94 95=== Version History 96 97 * Revision 1, 2017-08-16 (Aaron Hagan) 98 - Initial draft 99