1// Copyright 2020-2021 The Khronos Group Inc. 2// 3// SPDX-License-Identifier: CC-BY-4.0 4 5include::{generated}/meta/{refprefix}VK_EXT_fragment_density_map2.txt[] 6 7=== Other Extension Metadata 8 9*Last Modified Date*:: 10 2020-06-16 11*Interactions and External Dependencies*:: 12 - Interacts with Vulkan 1.1 13*Contributors*:: 14 - Matthew Netsch, Qualcomm Technologies, Inc. 15 - Jonathan Tinkham, Qualcomm Technologies, Inc. 16 - Jonathan Wicks, Qualcomm Technologies, Inc. 17 - Jan-Harald Fredriksen, ARM 18 19=== Description 20 21This extension adds additional features and properties to 22`apiext:VK_EXT_fragment_density_map` in order to reduce fragment density map 23host latency as well as improved queries for subsampled sampler 24implementation-dependent behavior. 25 26include::{generated}/interfaces/VK_EXT_fragment_density_map.txt[] 27 28=== Version History 29 30 * Revision 1, 2020-06-16 (Matthew Netsch) 31 - Initial version 32 33ifdef::isrefpage[] 34=== Examples 35 36==== Additional limits for subsampling 37 38Some implementations may not support subsampled samplers if certain 39implementation limits are not observed by the app. 40slink:VkPhysicalDeviceFragmentDensityMap2PropertiesEXT provides additional 41limits to require apps remain within these boundaries if they wish to use 42subsampling. 43 44==== Improved host latency 45 46By default, the fragment density map is locked by the host for reading 47between flink:vkCmdBeginRenderPass during recording and 48ename:VK_PIPELINE_STAGE_FRAGMENT_DENSITY_PROCESS_BIT_EXT during draw 49execution. 50 51This can introduce large latency for certain use cases between recording the 52frame and displaying the frame. 53Apps may wish to modify the fragment density map just before draw execution. 54 55ename:VK_IMAGE_VIEW_CREATE_FRAGMENT_DENSITY_MAP_DEFERRED_BIT_EXT is intended 56to help address this for implementations that do not support the 57<<features-fragmentdensitymapdynamic,fragmentDensityMapDynamic>> feature by 58deferring the start of the locked range to flink:vkEndCommandBuffer. 59 60 61[source,c++] 62---------------------------------------- 63// Create view for fragment density map 64VkImageViewCreateInfo createInfo = 65{ 66 VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO, 67 // ... 68 VK_IMAGE_VIEW_CREATE_FRAGMENT_DENSITY_MAP_DEFERRED_BIT_EXT, 69 fdmImage, // Created with VK_IMAGE_USAGE_FRAGMENT_DENSITY_MAP_BIT_EXT 70 // ... 71}; 72 73// ... 74 75// Begin fragment density map render pass with deferred view. 76// By default, fdmImage must not be modified after this call 77// unless view is created with the FDM dynamic or deferred flags. 78vkCmdBeginRenderPass(commandBuffer, pRenderPassBegin, contents); 79 80// ... 81 82vkCmdEndRenderPass(VkCommandBuffer commandBuffer); 83 84// Can keep making modifications to deferred fragment density maps 85// while recording commandBuffer ... 86 87result = vkEndCommandBuffer(commandBuffer); 88 89// Must now freeze modifying fdmImage until after the 90// VK_PIPELINE_STAGE_FRAGMENT_DENSITY_PROCESS_BIT_EXT of 91// the last executing draw that uses the fdmImage in the 92// last submit of commandBuffer. 93 94---------------------------------------- 95endif::isrefpage[] 96