1// Copyright 2017-2021 The Khronos Group Inc. 2// 3// SPDX-License-Identifier: CC-BY-4.0 4 5include::{generated}/meta/{refprefix}VK_EXT_descriptor_indexing.txt[] 6 7=== Other Extension Metadata 8 9*Last Modified Date*:: 10 2017-10-02 11*Interactions and External Dependencies*:: 12 - Promoted to Vulkan 1.2 Core 13*Contributors*:: 14 - Jeff Bolz, NVIDIA 15 - Daniel Rakos, AMD 16 - Slawomir Grajewski, Intel 17 - Tobias Hector, Imagination Technologies 18 19=== Description 20 21This extension adds several small features which together enable 22applications to create large descriptor sets containing substantially all of 23their resources, and selecting amongst those resources with dynamic 24(non-uniform) indexes in the shader. 25There are feature enables and SPIR-V capabilities for non-uniform descriptor 26indexing in the shader, and non-uniform indexing in the shader requires use 27of a new code:NonUniformEXT decoration defined in the 28`SPV_EXT_descriptor_indexing` SPIR-V extension. 29There are descriptor set layout binding creation flags enabling several 30features: 31 32 * Descriptors can be updated after they are bound to a command buffer, 33 such that the execution of the command buffer reflects the most recent 34 update to the descriptors. 35 * Descriptors that are not used by any pending command buffers can be 36 updated, which enables writing new descriptors for frame N+1 while frame 37 N is executing. 38 * Relax the requirement that all descriptors in a binding that is 39 "`statically used`" must be valid, such that descriptors that are not 40 accessed by a submission need not be valid and can be updated while that 41 submission is executing. 42 * The final binding in a descriptor set layout can have a variable size 43 (and unsized arrays of resources are allowed in the 44 `GL_EXT_nonuniform_qualifier` and `SPV_EXT_descriptor_indexing` 45 extensions). 46 47Note that it is valid for multiple descriptor arrays in a shader to use the 48same set and binding number, as long as they are all compatible with the 49descriptor type in the pipeline layout. 50This means a single array binding in the descriptor set can serve multiple 51texture dimensionalities, or an array of buffer descriptors can be used with 52multiple different block layouts. 53 54There are new descriptor set layout and descriptor pool creation flags that 55are required to opt in to the update-after-bind functionality, and there are 56separate pname:maxPerStage* and pname:maxDescriptorSet* limits that apply to 57these descriptor set layouts which may: be much higher than the pre-existing 58limits. 59The old limits only count descriptors in non-updateAfterBind descriptor set 60layouts, and the new limits count descriptors in all descriptor set layouts 61in the pipeline layout. 62 63include::{generated}/interfaces/VK_EXT_descriptor_indexing.txt[] 64 65=== Promotion to Vulkan 1.2 66 67Functionality in this extension is included in core Vulkan 1.2, with the EXT 68suffix omitted. 69However, if Vulkan 1.2 is supported and this extension is not, the 70code:descriptorIndexing capability is optional. 71The original type, enum and command names are still available as aliases of 72the core functionality. 73 74=== Version History 75 76 * Revision 1, 2017-07-26 (Jeff Bolz) 77 - Internal revisions 78 * Revision 2, 2017-10-02 (Jeff Bolz) 79 - ??? 80