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5abf83f95d
* Update release number to 107.
Public Issues:
* Fix revision date for the `<<VK_AMD_gpu_shader_half_float>>` appendix
(public issue 617).
* Make <<synchronization-pipeline-barriers-subpass-self-dependencies,
subpass self-dependencies>> less restrictive (public issue 777).
* Fix the `<<VK_EXT_full_screen_exclusive>>` dependency on
`<<VK_KHR_win32_surface>>` in `vk.xml` (public pull request 849).
* Remove single-page (`apispec.html`) refpage sub-targets from the
Makefile `allman` target and the build instructions. The target is still
present in the Makefile, but we have not been actively maintaining the
single-page document and do not promise it will work. The full
Specification and the individual API reference pages are what we support
and publish at present (public issue 949).
Internal Issues:
* De-duplicate common valid usage statements shared by multiple commands
or structures by using asciidoctor includes and dynamically assigning
part of the valid usage ID based on which command or structure they're
being applied to (internal issue 779).
* Add reference pages for constructs not part of the formal API, such as
platform calling convention macros, and script changes supporting them
This required suppressing some check_spec_links warning classes in order
to pass CI, until a more sophisticated fix can be done (internal issue
888).
* Change math notation for the elink:VkPrimitiveTopology descriptions to
use short forms `v` and `p` instead of `vertex` and `primitive`,
increasing legibility (internal issue 1611).
* Rewrite generated file includes relative to a globally specified path,
fixing some issues with refpage generation (internal issue 1630).
* Update contributor list for `<<VK_EXT_calibrated_timestamps>>`.
* Fix use of pathlin in `scripts/generator.py` so the script will work on
Windows under Python 3.5 (internal merge request 3107).
* Add missing conditionals around the
<<descriptorsets-accelerationstructure, Acceleration Structure>>
section (internal merge request 3108).
* More script synchronization with OpenXR spec repository (internal merge
request 3109).
* Mark the `<<VK_AMD_gpu_shader_half_float>>` and
`<<VK_AMD_gpu_shader_int16>>` extensions as deprecated in `vk.xml` and
the corresponding extension appendices (internal merge request 3112).
New Extensions:
* `<<VK_EXT_headless_surface>>`
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// Copyright (c) 2015-2019 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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[[fxvertex]]
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= Fixed-Function Vertex Processing
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Vertex fetching is controlled via configurable state, as a logically
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distinct graphics pipeline stage.
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[[fxvertex-attrib]]
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== Vertex Attributes
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Vertex shaders can: define input variables, which receive _vertex attribute_
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data transferred from one or more sname:VkBuffer(s) by drawing commands.
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Vertex shader input variables are bound to buffers via an indirect binding
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where the vertex shader associates a _vertex input attribute_ number with
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each variable, vertex input attributes are associated to _vertex input
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bindings_ on a per-pipeline basis, and vertex input bindings are associated
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with specific buffers on a per-draw basis via the
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fname:vkCmdBindVertexBuffers command.
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Vertex input attribute and vertex input binding descriptions also contain
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format information controlling how data is extracted from buffer memory and
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converted to the format expected by the vertex shader.
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There are sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
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number of vertex input attributes and
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sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings number of vertex
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input bindings (each referred to by zero-based indices), where there are at
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least as many vertex input attributes as there are vertex input bindings.
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Applications can: store multiple vertex input attributes interleaved in a
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single buffer, and use a single vertex input binding to access those
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attributes.
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In GLSL, vertex shaders associate input variables with a vertex input
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attribute number using the code:location layout qualifier.
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The code:component layout qualifier associates components of a vertex shader
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input variable with components of a vertex input attribute.
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.GLSL example
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[source,glsl]
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---------------------------------------------------
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// Assign location M to variableName
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layout (location=M, component=2) in vec2 variableName;
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// Assign locations [N,N+L) to the array elements of variableNameArray
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layout (location=N) in vec4 variableNameArray[L];
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---------------------------------------------------
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In SPIR-V, vertex shaders associate input variables with a vertex input
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attribute number using the code:Location decoration.
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The code:Component decoration associates components of a vertex shader input
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variable with components of a vertex input attribute.
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The code:Location and code:Component decorations are specified via the
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code:OpDecorate instruction.
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.SPIR-V example
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[source,spirv]
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---------------------------------------------------
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...
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%1 = OpExtInstImport "GLSL.std.450"
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...
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OpName %9 "variableName"
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OpName %15 "variableNameArray"
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OpDecorate %18 BuiltIn VertexIndex
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OpDecorate %19 BuiltIn InstanceIndex
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OpDecorate %9 Location M
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OpDecorate %9 Component 2
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OpDecorate %15 Location N
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...
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%2 = OpTypeVoid
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%3 = OpTypeFunction %2
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%6 = OpTypeFloat 32
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%7 = OpTypeVector %6 2
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%8 = OpTypePointer Input %7
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%9 = OpVariable %8 Input
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%10 = OpTypeVector %6 4
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%11 = OpTypeInt 32 0
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%12 = OpConstant %11 L
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%13 = OpTypeArray %10 %12
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%14 = OpTypePointer Input %13
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%15 = OpVariable %14 Input
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...
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---------------------------------------------------
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[[fxvertex-attrib-location]]
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=== Attribute Location and Component Assignment
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Vertex shaders allow code:Location and code:Component decorations on input
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variable declarations.
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The code:Location decoration specifies which vertex input attribute is used
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to read and interpret the data that a variable will consume.
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The code:Component decoration allows the location to be more finely
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specified for scalars and vectors, down to the individual components within
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a location that are consumed.
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The components within a location are 0, 1, 2, and 3.
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A variable starting at component N will consume components N, N+1, N+2, ...
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up through its size.
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For single precision types, it is invalid if the sequence of components gets
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larger than 3.
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When a vertex shader input variable declared using a scalar or vector 32-bit
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data type is assigned a location, its value(s) are taken from the components
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of the input attribute specified with the corresponding
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sname:VkVertexInputAttributeDescription::pname:location.
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The components used depend on the type of variable and the code:Component
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decoration specified in the variable declaration, as identified in
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<<fxvertex-attrib-components>>.
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Any 32-bit scalar or vector input will consume a single location.
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For 32-bit data types, missing components are filled in with default values
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as described <<fxvertex-input-extraction,below>>.
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[[fxvertex-attrib-components]]
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.Input attribute components accessed by 32-bit input variables
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[width="65%",cols="<5,<3,<3",options="header"]
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|====
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| 32-bit data type | code:Component decoration | Components consumed
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| scalar | 0 or unspecified | (x, o, o, o)
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| scalar | 1 | (o, y, o, o)
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| scalar | 2 | (o, o, z, o)
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| scalar | 3 | (o, o, o, w)
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| two-component vector | 0 or unspecified | (x, y, o, o)
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| two-component vector | 1 | (o, y, z, o)
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| two-component vector | 2 | (o, o, z, w)
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| three-component vector| 0 or unspecified | (x, y, z, o)
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| three-component vector| 1 | (o, y, z, w)
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| four-component vector | 0 or unspecified | (x, y, z, w)
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|====
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Components indicated by "`o`" are available for use by other input variables
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which are sourced from the same attribute, and if used, are either filled
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with the corresponding component from the input format (if present), or the
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default value.
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When a vertex shader input variable declared using a 32-bit floating point
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matrix type is assigned a location _i_, its values are taken from
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consecutive input attributes starting with the corresponding
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sname:VkVertexInputAttributeDescription::pname:location.
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Such matrices are treated as an array of column vectors with values taken
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from the input attributes identified in <<fxvertex-attrib-matrix>>.
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The sname:VkVertexInputAttributeDescription::pname:format must: be specified
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with a elink:VkFormat that corresponds to the appropriate type of column
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vector.
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The code:Component decoration must: not be used with matrix types.
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[[fxvertex-attrib-matrix]]
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.Input attributes accessed by 32-bit input matrix variables
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[width="100%",cols="<10%,<24%,<21%,<45%",options="header"]
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|====
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| Data type | Column vector type | Locations consumed | Components consumed
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| mat2 | two-component vector | i, i+1 | (x, y, o, o), (x, y, o, o)
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| mat2x3 | three-component vector | i, i+1 | (x, y, z, o), (x, y, z, o)
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| mat2x4 | four-component vector | i, i+1 | (x, y, z, w), (x, y, z, w)
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| mat3x2 | two-component vector | i, i+1, i+2 | (x, y, o, o), (x, y, o, o), (x, y, o, o)
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| mat3 | three-component vector | i, i+1, i+2 | (x, y, z, o), (x, y, z, o), (x, y, z, o)
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| mat3x4 | four-component vector | i, i+1, i+2 | (x, y, z, w), (x, y, z, w), (x, y, z, w)
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| mat4x2 | two-component vector | i, i+1, i+2, i+3 | (x, y, o, o), (x, y, o, o), (x, y, o, o), (x, y, o, o)
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| mat4x3 | three-component vector | i, i+1, i+2, i+3 | (x, y, z, o), (x, y, z, o), (x, y, z, o), (x, y, z, o)
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| mat4 | four-component vector | i, i+1, i+2, i+3 | (x, y, z, w), (x, y, z, w), (x, y, z, w), (x, y, z, w)
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|====
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Components indicated by "`o`" are available for use by other input variables
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which are sourced from the same attribute, and if used, are either filled
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with the corresponding component from the input (if present), or the default
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value.
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When a vertex shader input variable declared using a scalar or vector 64-bit
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data type is assigned a location _i_, its values are taken from consecutive
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input attributes starting with the corresponding
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sname:VkVertexInputAttributeDescription::pname:location.
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The locations and components used depend on the type of variable and the
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code:Component decoration specified in the variable declaration, as
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identified in <<fxvertex-attrib-double>>.
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For 64-bit data types, no default attribute values are provided.
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Input variables must: not use more components than provided by the
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attribute.
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Input attributes which have one- or two-component 64-bit formats will
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consume a single location.
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Input attributes which have three- or four-component 64-bit formats will
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consume two consecutive locations.
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A 64-bit scalar data type will consume two components, and a 64-bit
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two-component vector data type will consume all four components available
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within a location.
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A three- or four-component 64-bit data type must: not specify a component.
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A three-component 64-bit data type will consume all four components of the
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first location and components 0 and 1 of the second location.
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This leaves components 2 and 3 available for other component-qualified
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declarations.
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A four-component 64-bit data type will consume all four components of the
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first location and all four components of the second location.
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It is invalid for a scalar or two-component 64-bit data type to specify a
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component of 1 or 3.
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[[fxvertex-attrib-double]]
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.Input attribute locations and components accessed by 64-bit input variables
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[width="100%",cols="<18%,^12%,<25%,^14%,^18%,<13%",options="header"]
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|====
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^.^| Input format | Locations consumed
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^.^| 64-bit data type |code:Location decoration |code:Component decoration ^| 32-bit components consumed
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| R64 | i
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| scalar | i | 0 or unspecified | (x, y, -, -)
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.3+<.^| R64G64 .3+^.^| i
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| scalar | i | 0 or unspecified | (x, y, o, o)
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| scalar | i | 2 | (o, o, z, w)
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| two-component vector | i | 0 or unspecified | (x, y, z, w)
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.5+<.^| R64G64B64 .5+^.^| i, i+1
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| scalar | i | 0 or unspecified | (x, y, o, o), (o, o, -, -)
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| scalar | i | 2 | (o, o, z, w), (o, o, -, -)
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| scalar | i+1 | 0 or unspecified | (o, o, o, o), (x, y, -, -)
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| two-component vector | i | 0 or unspecified | (x, y, z, w), (o, o, -, -)
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| three-component vector | i | unspecified | (x, y, z, w), (x, y, -, -)
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.8+<.^| R64G64B64A64 .8+^.^| i, i+1
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| scalar | i | 0 or unspecified | (x, y, o, o), (o, o, o, o)
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| scalar | i | 2 | (o, o, z, w), (o, o, o, o)
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| scalar | i+1 | 0 or unspecified | (o, o, o, o), (x, y, o, o)
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| scalar | i+1 | 2 | (o, o, o, o), (o, o, z, w)
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| two-component vector | i | 0 or unspecified | (x, y, z, w), (o, o, o, o)
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| two-component vector | i+1 | 0 or unspecified | (o, o, o, o), (x, y, z, w)
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| three-component vector | i | unspecified | (x, y, z, w), (x, y, o, o)
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| four-component vector | i | unspecified | (x, y, z, w), (x, y, z, w)
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|====
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Components indicated by "`o`" are available for use by other input variables
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which are sourced from the same attribute.
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Components indicated by "`-`" are not available for input variables as there
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are no default values provided for 64-bit data types, and there is no data
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provided by the input format.
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When a vertex shader input variable declared using a 64-bit floating-point
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matrix type is assigned a location _i_, its values are taken from
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consecutive input attribute locations.
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Such matrices are treated as an array of column vectors with values taken
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from the input attributes as shown in <<fxvertex-attrib-double>>.
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Each column vector starts at the location immediately following the last
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location of the previous column vector.
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The number of attributes and components assigned to each matrix is
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determined by the matrix dimensions and ranges from two to eight locations.
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When a vertex shader input variable declared using an array type is assigned
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a location, its values are taken from consecutive input attributes starting
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with the corresponding
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sname:VkVertexInputAttributeDescription::pname:location.
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The number of attributes and components assigned to each element are
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determined according to the data type of the array elements and
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code:Component decoration (if any) specified in the declaration of the
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array, as described above.
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Each element of the array, in order, is assigned to consecutive locations,
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but all at the same specified component within each location.
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Only input variables declared with the data types and component decorations
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as specified above are supported.
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_Location aliasing_ is causing two variables to have the same location
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number.
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_Component aliasing_ is assigning the same (or overlapping) component number
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for two location aliases.
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Location aliasing is allowed only if it does not cause component aliasing.
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Further, when location aliasing, the aliases sharing the location must: all
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have the same SPIR-V floating-point component type or all have the same
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width integer-type components.
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[[fxvertex-input]]
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== Vertex Input Description
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Applications specify vertex input attribute and vertex input binding
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descriptions as part of graphics pipeline creation.
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The slink:VkGraphicsPipelineCreateInfo::pname:pVertexInputState points to a
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structure of type sname:VkPipelineVertexInputStateCreateInfo.
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[open,refpage='VkPipelineVertexInputStateCreateInfo',desc='Structure specifying parameters of a newly created pipeline vertex input state',type='structs']
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--
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The sname:VkPipelineVertexInputStateCreateInfo structure is defined as:
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include::{generated}/api/structs/VkPipelineVertexInputStateCreateInfo.txt[]
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* pname:sType is the type of this structure.
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* pname:pNext is `NULL` or a pointer to an extension-specific structure.
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* pname:flags is reserved for future use.
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* pname:vertexBindingDescriptionCount is the number of vertex binding
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descriptions provided in pname:pVertexBindingDescriptions.
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* pname:pVertexBindingDescriptions is a pointer to an array of
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sname:VkVertexInputBindingDescription structures.
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* pname:vertexAttributeDescriptionCount is the number of vertex attribute
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descriptions provided in pname:pVertexAttributeDescriptions.
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* pname:pVertexAttributeDescriptions is a pointer to an array of
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sname:VkVertexInputAttributeDescription structures.
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.Valid Usage
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****
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* [[VUID-VkPipelineVertexInputStateCreateInfo-vertexBindingDescriptionCount-00613]]
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pname:vertexBindingDescriptionCount must: be less than or equal to
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sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
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* [[VUID-VkPipelineVertexInputStateCreateInfo-vertexAttributeDescriptionCount-00614]]
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pname:vertexAttributeDescriptionCount must: be less than or equal to
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sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
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* [[VUID-VkPipelineVertexInputStateCreateInfo-binding-00615]]
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For every pname:binding specified by each element of
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pname:pVertexAttributeDescriptions, a
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sname:VkVertexInputBindingDescription must: exist in
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pname:pVertexBindingDescriptions with the same value of pname:binding
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* [[VUID-VkPipelineVertexInputStateCreateInfo-pVertexBindingDescriptions-00616]]
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All elements of pname:pVertexBindingDescriptions must: describe distinct
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binding numbers
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* [[VUID-VkPipelineVertexInputStateCreateInfo-pVertexAttributeDescriptions-00617]]
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All elements of pname:pVertexAttributeDescriptions must: describe
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distinct attribute locations
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****
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include::{generated}/validity/structs/VkPipelineVertexInputStateCreateInfo.txt[]
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--
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[open,refpage='VkPipelineVertexInputStateCreateFlags',desc='Reserved for future use',type='flags']
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--
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include::{generated}/api/flags/VkPipelineVertexInputStateCreateFlags.txt[]
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tname:VkPipelineVertexInputStateCreateFlags is a bitmask type for setting a
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mask, but is currently reserved for future use.
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--
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Each vertex input binding is specified by an instance of the
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sname:VkVertexInputBindingDescription structure.
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[open,refpage='VkVertexInputBindingDescription',desc='Structure specifying vertex input binding description',type='structs']
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--
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The sname:VkVertexInputBindingDescription structure is defined as:
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include::{generated}/api/structs/VkVertexInputBindingDescription.txt[]
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* pname:binding is the binding number that this structure describes.
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* pname:stride is the distance in bytes between two consecutive elements
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within the buffer.
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* pname:inputRate is a elink:VkVertexInputRate value specifying whether
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vertex attribute addressing is a function of the vertex index or of the
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instance index.
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.Valid Usage
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****
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* [[VUID-VkVertexInputBindingDescription-binding-00618]]
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pname:binding must: be less than
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sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
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* [[VUID-VkVertexInputBindingDescription-stride-00619]]
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pname:stride must: be less than or equal to
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sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindingStride
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****
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include::{generated}/validity/structs/VkVertexInputBindingDescription.txt[]
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--
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[open,refpage='VkVertexInputRate',desc='Specify rate at which vertex attributes are pulled from buffers',type='enums']
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--
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Possible values of slink:VkVertexInputBindingDescription::pname:inputRate,
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specifying the rate at which vertex attributes are pulled from buffers, are:
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include::{generated}/api/enums/VkVertexInputRate.txt[]
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* ename:VK_VERTEX_INPUT_RATE_VERTEX specifies that vertex attribute
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addressing is a function of the vertex index.
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* ename:VK_VERTEX_INPUT_RATE_INSTANCE specifies that vertex attribute
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addressing is a function of the instance index.
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|
|
|
--
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[open,refpage='VkVertexInputAttributeDescription',desc='Structure specifying vertex input attribute description',type='structs']
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|
--
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Each vertex input attribute is specified by an instance of the
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sname:VkVertexInputAttributeDescription structure.
|
|
|
|
The sname:VkVertexInputAttributeDescription structure is defined as:
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|
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|
include::{generated}/api/structs/VkVertexInputAttributeDescription.txt[]
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|
|
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* pname:location is the shader binding location number for this attribute.
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* pname:binding is the binding number which this attribute takes its data
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from.
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* pname:format is the size and type of the vertex attribute data.
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|
* pname:offset is a byte offset of this attribute relative to the start of
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an element in the vertex input binding.
|
|
|
|
.Valid Usage
|
|
****
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|
* [[VUID-VkVertexInputAttributeDescription-location-00620]]
|
|
pname:location must: be less than
|
|
sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
|
|
* [[VUID-VkVertexInputAttributeDescription-binding-00621]]
|
|
pname:binding must: be less than
|
|
sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
|
|
* [[VUID-VkVertexInputAttributeDescription-offset-00622]]
|
|
pname:offset must: be less than or equal to
|
|
sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributeOffset
|
|
* [[VUID-VkVertexInputAttributeDescription-format-00623]]
|
|
pname:format must: be allowed as a vertex buffer format, as specified by
|
|
the ename:VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT flag in
|
|
sname:VkFormatProperties::pname:bufferFeatures returned by
|
|
fname:vkGetPhysicalDeviceFormatProperties
|
|
****
|
|
|
|
include::{generated}/validity/structs/VkVertexInputAttributeDescription.txt[]
|
|
--
|
|
|
|
[open,refpage='vkCmdBindVertexBuffers',desc='Bind vertex buffers to a command buffer',type='protos']
|
|
--
|
|
|
|
To bind vertex buffers to a command buffer for use in subsequent draw
|
|
commands, call:
|
|
|
|
include::{generated}/api/protos/vkCmdBindVertexBuffers.txt[]
|
|
|
|
* pname:commandBuffer is the command buffer into which the command is
|
|
recorded.
|
|
* pname:firstBinding is the index of the first vertex input binding whose
|
|
state is updated by the command.
|
|
* pname:bindingCount is the number of vertex input bindings whose state is
|
|
updated by the command.
|
|
* pname:pBuffers is a pointer to an array of buffer handles.
|
|
* pname:pOffsets is a pointer to an array of buffer offsets.
|
|
|
|
The values taken from elements [eq]#i# of pname:pBuffers and pname:pOffsets
|
|
replace the current state for the vertex input binding
|
|
[eq]#pname:firstBinding {plus} i#, for [eq]#i# in [eq]#[0,
|
|
pname:bindingCount)#.
|
|
The vertex input binding is updated to start at the offset indicated by
|
|
pname:pOffsets[i] from the start of the buffer pname:pBuffers[i].
|
|
All vertex input attributes that use each of these bindings will use these
|
|
updated addresses in their address calculations for subsequent draw
|
|
commands.
|
|
|
|
.Valid Usage
|
|
****
|
|
* [[VUID-vkCmdBindVertexBuffers-firstBinding-00624]]
|
|
pname:firstBinding must: be less than
|
|
sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
|
|
* [[VUID-vkCmdBindVertexBuffers-firstBinding-00625]]
|
|
The sum of pname:firstBinding and pname:bindingCount must: be less than
|
|
or equal to sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
|
|
* [[VUID-vkCmdBindVertexBuffers-pOffsets-00626]]
|
|
All elements of pname:pOffsets must: be less than the size of the
|
|
corresponding element in pname:pBuffers
|
|
* [[VUID-vkCmdBindVertexBuffers-pBuffers-00627]]
|
|
All elements of pname:pBuffers must: have been created with the
|
|
ename:VK_BUFFER_USAGE_VERTEX_BUFFER_BIT flag
|
|
* [[VUID-vkCmdBindVertexBuffers-pBuffers-00628]]
|
|
Each element of pname:pBuffers that is non-sparse must: be bound
|
|
completely and contiguously to a single sname:VkDeviceMemory object
|
|
****
|
|
|
|
include::{generated}/validity/protos/vkCmdBindVertexBuffers.txt[]
|
|
--
|
|
|
|
ifdef::VK_EXT_vertex_attribute_divisor[]
|
|
|
|
== Vertex Attribute Divisor in Instanced Rendering
|
|
|
|
[open,refpage='VkPipelineVertexInputDivisorStateCreateInfoEXT',desc='Structure specifying vertex attributes assignment during instanced rendering',type='structs']
|
|
--
|
|
|
|
If
|
|
<<features-vertexAttributeInstanceRateDivisor,pname:vertexAttributeInstanceRateDivisor>>
|
|
feature is enabled and the pname:pNext chain of
|
|
slink:VkPipelineVertexInputStateCreateInfo includes a
|
|
sname:VkPipelineVertexInputDivisorStateCreateInfoEXT structure, then that
|
|
structure controls how vertex attributes are assigned to an instance when
|
|
instanced rendering is enabled.
|
|
|
|
The sname:VkPipelineVertexInputDivisorStateCreateInfoEXT structure is
|
|
defined as:
|
|
|
|
include::{generated}/api/structs/VkPipelineVertexInputDivisorStateCreateInfoEXT.txt[]
|
|
|
|
* pname:sType is the type of this structure
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure
|
|
* pname:vertexBindingDivisorCount is the number of elements in the
|
|
pname:pVertexBindingDivisors array.
|
|
* pname:pVertexBindingDivisors is a pointer to an array of
|
|
sname:VkVertexInputBindingDivisorDescriptionEXT structures, which
|
|
specifies the divisor value for each binding.
|
|
|
|
include::{generated}/validity/structs/VkPipelineVertexInputDivisorStateCreateInfoEXT.txt[]
|
|
--
|
|
|
|
[open,refpage='VkVertexInputBindingDivisorDescriptionEXT',desc='Structure specifying a divisor used in instanced rendering',type='structs']
|
|
--
|
|
The individual divisor values per binding are specified using the
|
|
sname:VkVertexInputBindingDivisorDescriptionEXT structure which is defined
|
|
as:
|
|
|
|
include::{generated}/api/structs/VkVertexInputBindingDivisorDescriptionEXT.txt[]
|
|
|
|
* pname:binding is the binding number for which the divisor is specified.
|
|
* pname:divisor is the number of successive instances that will use the
|
|
same value of the vertex attribute when instanced rendering is enabled.
|
|
For example, if the divisor is N, the same vertex attribute will applied
|
|
to N successive instances before moving on to the next vertex attribute.
|
|
The maximum value of divisor is implementation dependent and can be
|
|
queried using
|
|
sname:VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT::pname:maxVertexAttribDivisor.
|
|
A value of `0` can: be used for the divisor if the
|
|
<<features-vertexAttributeInstanceRateZeroDivisor,pname:vertexAttributeInstanceRateZeroDivisor>>
|
|
feature is enabled.
|
|
In this case, the same vertex attribute will be applied to all
|
|
instances.
|
|
|
|
If this structure is not used to define a divisor value for an attribute
|
|
then the divisor has a logical default value of 1.
|
|
|
|
.Valid Usage
|
|
****
|
|
* [[VUID-VkVertexInputBindingDivisorDescriptionEXT-binding-01869]]
|
|
pname:binding must: be less than
|
|
sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
|
|
* [[VUID-VkVertexInputBindingDivisorDescriptionEXT-vertexAttributeInstanceRateZeroDivisor-02228]]
|
|
If the pname:vertexAttributeInstanceRateZeroDivisor feature is not
|
|
enabled, pname:divisor must: not be `0`
|
|
* [[VUID-VkVertexInputBindingDivisorDescriptionEXT-vertexAttributeInstanceRateDivisor-02229]]
|
|
If the pname:vertexAttributeInstanceRateDivisor feature is not enabled,
|
|
pname:divisor must: be `1`
|
|
* [[VUID-VkVertexInputBindingDivisorDescriptionEXT-divisor-01870]]
|
|
pname:divisor must: be a value between `0` and
|
|
sname:VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT::pname:maxVertexAttribDivisor,
|
|
inclusive.
|
|
* [[VUID-VkVertexInputBindingDivisorDescriptionEXT-inputRate-01871]]
|
|
slink:VkVertexInputBindingDescription::pname:inputRate must: be of type
|
|
ename:VK_VERTEX_INPUT_RATE_INSTANCE for this pname:binding.
|
|
****
|
|
|
|
include::{generated}/validity/structs/VkVertexInputBindingDivisorDescriptionEXT.txt[]
|
|
--
|
|
|
|
endif::VK_EXT_vertex_attribute_divisor[]
|
|
|
|
The address of each attribute for each code:vertexIndex and
|
|
code:instanceIndex is calculated as follows:
|
|
|
|
* Let code:attribDesc be the member of
|
|
sname:VkPipelineVertexInputStateCreateInfo::pname:pVertexAttributeDescriptions
|
|
with sname:VkVertexInputAttributeDescription::pname:location equal to
|
|
the vertex input attribute number.
|
|
* Let code:bindingDesc be the member of
|
|
sname:VkPipelineVertexInputStateCreateInfo::pname:pVertexBindingDescriptions
|
|
with sname:VkVertexInputAttributeDescription::pname:binding equal to
|
|
code:attribDesc.binding.
|
|
* Let code:vertexIndex be the index of the vertex within the draw (a value
|
|
between pname:firstVertex and pname:firstVertex+pname:vertexCount for
|
|
fname:vkCmdDraw, or a value taken from the index buffer for
|
|
fname:vkCmdDrawIndexed), and let code:instanceIndex be the instance
|
|
number of the draw (a value between pname:firstInstance and
|
|
pname:firstInstance+pname:instanceCount).
|
|
ifdef::VK_EXT_vertex_attribute_divisor[]
|
|
* Let code:divisor be the member of
|
|
sname:VkPipelineVertexInputDivisorStateCreateInfoEXT::pname:pVertexBindingDivisors
|
|
with sname:VkVertexInputBindingDivisorDescriptionEXT::pname:binding
|
|
equal to code:attribDesc.binding.
|
|
endif::VK_EXT_vertex_attribute_divisor[]
|
|
|
|
[source,c]
|
|
---------------------------------------------------
|
|
bufferBindingAddress = buffer[binding].baseAddress + offset[binding];
|
|
|
|
if (bindingDesc.inputRate == VK_VERTEX_INPUT_RATE_VERTEX)
|
|
vertexOffset = vertexIndex * bindingDesc.stride;
|
|
else
|
|
ifndef::VK_EXT_vertex_attribute_divisor[]
|
|
vertexOffset = instanceIndex * bindingDesc.stride;
|
|
endif::VK_EXT_vertex_attribute_divisor[]
|
|
ifdef::VK_EXT_vertex_attribute_divisor[]
|
|
if (divisor == 0)
|
|
vertexOffset = firstInstance * bindingDesc.stride;
|
|
else
|
|
vertexOffset = (firstInstance + ((instanceIndex - firstInstance) / divisor)) * bindingDesc.stride;
|
|
endif::VK_EXT_vertex_attribute_divisor[]
|
|
|
|
attribAddress = bufferBindingAddress + vertexOffset + attribDesc.offset;
|
|
---------------------------------------------------
|
|
|
|
[[fxvertex-input-extraction]]
|
|
For each attribute, raw data is extracted starting at `attribAddress` and is
|
|
converted from the sname:VkVertexInputAttributeDescription's pname:format to
|
|
either to floating-point, unsigned integer, or signed integer based on the
|
|
base type of the format; the base type of the format must: match the base
|
|
type of the input variable in the shader.
|
|
If pname:format is a packed format, `attribAddress` must: be a multiple of
|
|
the size in bytes of the whole attribute data type as described in
|
|
<<formats-packed,Packed Formats>>.
|
|
Otherwise, `attribAddress` must: be a multiple of the size in bytes of the
|
|
component type indicated by pname:format (see <<formats,Formats>>).
|
|
If the format does not include G, B, or A components, then those are filled
|
|
with [eq]#(0,0,1)# as needed (using either 1.0f or integer 1 based on the
|
|
format) for attributes that are not 64-bit data types.
|
|
The number of components in the vertex shader input variable need not
|
|
exactly match the number of components in the format.
|
|
If the vertex shader has fewer components, the extra components are
|
|
discarded.
|
|
|
|
[[fxvertex-example]]
|
|
== Example
|
|
|
|
To create a graphics pipeline that uses the following vertex description:
|
|
|
|
[source,c++]
|
|
---------------------------------------------------
|
|
struct Vertex
|
|
{
|
|
float x, y, z, w;
|
|
uint8_t u, v;
|
|
};
|
|
---------------------------------------------------
|
|
|
|
The application could use the following set of structures:
|
|
|
|
[source,c++]
|
|
---------------------------------------------------
|
|
const VkVertexInputBindingDescription binding =
|
|
{
|
|
0, // binding
|
|
sizeof(Vertex), // stride
|
|
VK_VERTEX_INPUT_RATE_VERTEX // inputRate
|
|
};
|
|
|
|
const VkVertexInputAttributeDescription attributes[] =
|
|
{
|
|
{
|
|
0, // location
|
|
binding.binding, // binding
|
|
VK_FORMAT_R32G32B32A32_SFLOAT, // format
|
|
0 // offset
|
|
},
|
|
{
|
|
1, // location
|
|
binding.binding, // binding
|
|
VK_FORMAT_R8G8_UNORM, // format
|
|
4 * sizeof(float) // offset
|
|
}
|
|
};
|
|
|
|
const VkPipelineVertexInputStateCreateInfo viInfo =
|
|
{
|
|
VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_CREATE_INFO, // sType
|
|
NULL, // pNext
|
|
0, // flags
|
|
1, // vertexBindingDescriptionCount
|
|
&binding, // pVertexBindingDescriptions
|
|
2, // vertexAttributeDescriptionCount
|
|
&attributes[0] // pVertexAttributeDescriptions
|
|
};
|
|
---------------------------------------------------
|