140 lines
4.6 KiB
Plaintext
140 lines
4.6 KiB
Plaintext
// Copyright (c) 2016-2018 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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include::meta/VK_KHR_maintenance2.txt[]
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*Last Modified Date*::
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2017-04-28
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*Contributors*::
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- Michael Worcester, Imagination Technologies
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- Stuart Smith, Imagination Technologies
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- Jeff Bolz, NVIDIA
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- Daniel Koch, NVIDIA
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- Jan-Harald Fredriksen, ARM
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- Daniel Rakos, AMD
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- Neil Henning, Codeplay
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- Piers Daniell, NVIDIA
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`VK_KHR_maintenance2` adds a collection of minor features that were
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intentionally left out or overlooked from the original Vulkan 1.0 release.
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The new features are as follows:
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* Allow the application to specify which aspect of an input attachment
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might be read for a given subpass.
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* Allow implementations to express the clipping behavior of points.
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* Allow creating images with usage flags that may not be supported for the
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base image's format, but are supported for image views of the image that
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have a different but compatible format.
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* Allow creating uncompressed image views of compressed images.
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* Allow the application to select between an upper-left and lower-left
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origin for the tessellation domain space.
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* Adds two new image layouts for depth stencil images to allow either the
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depth or stencil aspect to be read-only while the other aspect is
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writable.
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=== Input Attachment Specification
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Input attachment specification allows an application to specify which aspect
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of a multi-aspect image (e.g. a combined depth stencil format) will be
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accessed via a code:subpassLoad operation.
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On some implementations there may: be a performance penalty if the
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implementation does not know (at flink:vkCreateRenderPass time) which
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aspect(s) of multi-aspect images can: be be accessed as input attachments.
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=== New Object Types
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None.
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=== New Enum Constants
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* Extending elink:VkStructureType:
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** ename:VK_STRUCTURE_TYPE_RENDER_PASS_INPUT_ATTACHMENT_ASPECT_CREATE_INFO_KHR
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_POINT_CLIPPING_PROPERTIES_KHR
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** ename:VK_STRUCTURE_TYPE_IMAGE_VIEW_USAGE_CREATE_INFO_KHR
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** ename:VK_STRUCTURE_TYPE_PIPELINE_TESSELLATION_DOMAIN_ORIGIN_STATE_CREATE_INFO_KHR
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* Extending elink:VkImageCreateFlagBits:
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** ename:VK_IMAGE_CREATE_BLOCK_TEXEL_VIEW_COMPATIBLE_BIT_KHR
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** ename:VK_IMAGE_CREATE_EXTENDED_USAGE_BIT_KHR
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* Extending elink:VkImageLayout
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** ename:VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL_KHR
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** ename:VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMAL_KHR
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* ename:VK_POINT_CLIPPING_BEHAVIOR_ALL_CLIP_PLANES_KHR
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* ename:VK_POINT_CLIPPING_BEHAVIOR_USER_CLIP_PLANES_ONLY_KHR
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=== New Enums
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* slink:VkPointClippingBehaviorKHR
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* slink:VkTessellationDomainOriginKHR
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=== New Structures
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* slink:VkPhysicalDevicePointClippingPropertiesKHR
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* slink:VkRenderPassInputAttachmentAspectCreateInfoKHR
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* slink:VkInputAttachmentAspectReferenceKHR
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* slink:VkImageViewUsageCreateInfoKHR
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* slink:VkPipelineTessellationDomainOriginStateCreateInfoKHR
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=== New Functions
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None.
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=== Input Attachment Specification Example
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Consider the case where a render pass has two subpasses and two attachments.
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Attachment 0 has the format ename:VK_FORMAT_D24_UNORM_S8_UINT, attachment 1
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has some color format.
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Subpass 0 writes to attachment 0, subpass 1 reads only the depth information
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from attachment 0 (using inputAttachmentRead) and writes to attachment 1.
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[source,c++]
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----------------------------------------
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VkInputAttachmentAspectReferenceKHR references[] = {
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{
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.subpass = 1,
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.inputAttachment = 0,
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.aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT
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}
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};
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VkRenderPassInputAttachmentAspectCreateInfoKHR specifyAspects = {
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.sType = VK_STRUCTURE_TYPE_RENDER_PASS_INPUT_ATTACHMENT_ASPECT_CREATE_INFO_KHR,
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.pNext = NULL,
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.aspectReferenceCount = 1,
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.pAspectReferences = references
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};
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VkRenderPassCreateInfo createInfo = {
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...
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.pNext = &specifyAspects,
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...
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}
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vkCreateRenderPass(...);
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----------------------------------------
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=== Issues
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1) What is the default tessellation domain origin?
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*RESOLVED*: Vulkan 1.0 originally inadvertently documented a lower-left
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origin, but the conformance tests and all implementations implemented an
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upper-left origin.
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This extension adds a control to select between lower-left (for
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compatibility with OpenGL) and upper-left, and we retroactively fix
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unextended Vulkan to have a default of an upper-left origin.
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=== Version History
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* Revision 1, 2017-04-28
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