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* Update release number to 124.
Github Issues:
* Fix Makefile SPECREMARK macro to work when not building in a git tree
(public issue 992).
* Ignore pname:aspectMask for unused attachments in
slink:VkSubpassDescription2KHR valid usage statements (public pull
request 1028).
* Minor markup / spelling fixes (public pull requests 1035, 1045).
Internal Issues:
* Fix markup in Valid Usage statement for slink:VkCreateFramebuffer
(internal issue 1823).
* Add a new <<synchronization-signal-operation-order, _signal operation
order_>> section to the synchronization chapter which describes in
detail the ordering guarantees provided by the API between fence and
semaphore signal operations (internal merge request 3368).
* Move generated `appendix/meta/` files into the Makefile GENERATED
directory (internal merge request 3381).
New Extensions
* `<<VK_KHR_shader_clock>>`
* `<<VK_KHR_timeline_semaphore>>`
109 lines
3.3 KiB
Plaintext
109 lines
3.3 KiB
Plaintext
include::{generated}/meta/VK_EXT_vertex_attribute_divisor.txt[]
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*Last Modified Date*::
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2018-08-03
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*IP Status*::
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No known IP claims.
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*Contributors*::
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- Vikram Kushwaha, NVIDIA
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- Jason Ekstrand, Intel
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This extension allows instance-rate vertex attributes to be repeated for
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certain number of instances instead of advancing for every instance when
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instanced rendering is enabled.
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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_PHYSICAL_DEVICE_VERTEX_ATTRIBUTE_DIVISOR_PROPERTIES_EXT
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** ename:VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_DIVISOR_STATE_CREATE_INFO_EXT
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VERTEX_ATTRIBUTE_DIVISOR_FEATURES_EXT
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=== New Enums
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None.
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=== New Structures
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* Extending slink:VkPipelineVertexInputStateCreateInfo:
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** slink:VkPipelineVertexInputDivisorStateCreateInfoEXT
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* slink:VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT
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* slink:VkVertexInputBindingDivisorDescriptionEXT
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* Extending slink:VkPhysicalDeviceFeatures2:
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** slink:VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT
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=== New Functions
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None.
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=== Issues
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1) What is the effect of a non-zero value for pname:firstInstance?
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*RESOLVED*: The Vulkan API should follow the OpenGL convention and offset
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attribute fetching by pname:firstInstance while computing vertex attribute
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offsets.
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2) Should zero be an allowed divisor?
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*RESOLVED*: Yes.
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A zero divisor means the vertex attribute is repeated for all instances.
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=== Examples
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To create a vertex binding such that the first binding uses instanced
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rendering and the same attribute is used for every 4 draw instances, an
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application could use the following set of structures:
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[source,c++]
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----------------------------------------
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const VkVertexInputBindingDivisorDescriptionEXT divisorDesc =
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{
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0,
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4
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};
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const VkPipelineVertexInputDivisorStateCreateInfoEXT divisorInfo =
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{
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VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_DIVISOR_STATE_CREATE_INFO_EXT, // sType
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NULL, // pNext
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1, // vertexBindingDivisorCount
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&divisorDesc // pVertexBindingDivisors
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}
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const VkVertexInputBindingDescription binding =
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{
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0, // binding
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sizeof(Vertex), // stride
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VK_VERTEX_INPUT_RATE_INSTANCE // inputRate
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};
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const VkPipelineVertexInputStateCreateInfo viInfo =
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{
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VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_CREATE_INFO, // sType
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&divisorInfo, // pNext
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...
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};
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//...
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----------------------------------------
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=== Version History
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* Revision 1, 2017-12-04 (Vikram Kushwaha)
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- First Version
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* Revision 2, 2018-07-16 (Jason Ekstrand)
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- Adjust the interaction between pname:divisor and pname:firstInstance
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to match the OpenGL convention.
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- Disallow divisors of zero.
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* Revision 3, 2018-08-03 (Vikram Kushwaha)
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- Allow a zero divisor.
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- Add a physical device features structure to query/enable this feature.
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