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6377124f37
* Update release number to 81.
Public Issues:
* Fix missing "`valid`" phrasing in some obscure cases (public pull
request 605).
* Replace improper use of cannot: referring to the implementation in the
description of the
<<features-limits-maxUpdateAfterBindDescriptorsInAllPools,
pname:maxUpdateAfterBindDescriptorsInAllPools>> limit (public pull
request 738).
* Reorder description of bits in elink:VkPipelineStageFlagBits and the
<<synchronization-pipeline-stages-supported, Supported pipeline stage
flags>> table to match their definition order (public pull request 740).
* Add description of ename:VK_BUFFER_USAGE_CONDITIONAL_RENDERING_BIT_EXT
to elink:VkBufferUsageFlagBits (public pull request 741).
* Fix value usage statement for slink:VkSubpassDependency stage mask
parameters (public pull request 742).
* Fix visible markup in registry schema document (public pull request
#745).
Internal Issues:
* Make the <<geometry-invocations, geometry shader invocation
description>> and <<shaders-geometry-execution, Geometry Shader
Execution>> descriptions consistent with other pipeline stages (internal
issue 1325).
* Mark the `VK_NV_glsl_shader` extension as deprecated.
* Adjust the per-instance vertex attribute offset formula specified by
`VK_EXT_vertex_attribute_divisor` for
slink:VkVertexInputBindingDivisorDescriptionEXT so that the interaction
between pname:firstInstance and pname:divisor matches the OpenGL
convention (internal issue 1333).
104 lines
3.0 KiB
Plaintext
104 lines
3.0 KiB
Plaintext
include::meta/VK_EXT_vertex_attribute_divisor.txt[]
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*Last Modified Date*::
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2018-07-16
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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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=== 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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=== 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*: No.
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The zero case in OpenGL is handled in Vulkan by setting the pname:inputRate
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on the binding to ename:VK_VERTEX_INPUT_RATE_VERTEX.
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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 fname: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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