// Copyright 2015-2021 The Khronos Group, Inc.
//
// SPDX-License-Identifier: CC-BY-4.0

[[fxvertex]]
= Fixed-Function Vertex Processing

Vertex fetching is controlled via configurable state, as a logically
distinct graphics pipeline stage.


[[fxvertex-attrib]]
== Vertex Attributes

Vertex shaders can: define input variables, which receive _vertex attribute_
data transferred from one or more sname:VkBuffer(s) by drawing commands.
Vertex shader input variables are bound to buffers via an indirect binding
where the vertex shader associates a _vertex input attribute_ number with
each variable, vertex input attributes are associated to _vertex input
bindings_ on a per-pipeline basis, and vertex input bindings are associated
with specific buffers on a per-draw basis via the
fname:vkCmdBindVertexBuffers command.
Vertex input attribute and vertex input binding descriptions also contain
format information controlling how data is extracted from buffer memory and
converted to the format expected by the vertex shader.

There are sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
number of vertex input attributes and
sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings number of vertex
input bindings (each referred to by zero-based indices), where there are at
least as many vertex input attributes as there are vertex input bindings.
Applications can: store multiple vertex input attributes interleaved in a
single buffer, and use a single vertex input binding to access those
attributes.

In GLSL, vertex shaders associate input variables with a vertex input
attribute number using the code:location layout qualifier.
The code:component layout qualifier associates components of a vertex shader
input variable with components of a vertex input attribute.

.GLSL example
[source,glsl]
---------------------------------------------------
// Assign location M to variableName
layout (location=M, component=2) in vec2 variableName;

// Assign locations [N,N+L) to the array elements of variableNameArray
layout (location=N) in vec4 variableNameArray[L];
---------------------------------------------------

In SPIR-V, vertex shaders associate input variables with a vertex input
attribute number using the code:Location decoration.
The code:Component decoration associates components of a vertex shader input
variable with components of a vertex input attribute.
The code:Location and code:Component decorations are specified via the
code:OpDecorate instruction.

.SPIR-V example
[source,spirv]
---------------------------------------------------
               ...
          %1 = OpExtInstImport "GLSL.std.450"
               ...
               OpName %9 "variableName"
               OpName %15 "variableNameArray"
               OpDecorate %18 BuiltIn VertexIndex
               OpDecorate %19 BuiltIn InstanceIndex
               OpDecorate %9 Location M
               OpDecorate %9 Component 2
               OpDecorate %15 Location N
               ...
          %2 = OpTypeVoid
          %3 = OpTypeFunction %2
          %6 = OpTypeFloat 32
          %7 = OpTypeVector %6 2
          %8 = OpTypePointer Input %7
          %9 = OpVariable %8 Input
         %10 = OpTypeVector %6 4
         %11 = OpTypeInt 32 0
         %12 = OpConstant %11 L
         %13 = OpTypeArray %10 %12
         %14 = OpTypePointer Input %13
         %15 = OpVariable %14 Input
               ...
---------------------------------------------------


[[fxvertex-attrib-location]]
=== Attribute Location and Component Assignment

Vertex shaders allow code:Location and code:Component decorations on input
variable declarations.
The code:Location decoration specifies which vertex input attribute is used
to read and interpret the data that a variable will consume.
The code:Component decoration allows the location to be more finely
specified for scalars and vectors, down to the individual components within
a location that are consumed.
The components within a location are 0, 1, 2, and 3.
A variable starting at component N will consume components N, N+1, N+2, ...
up through its size.
For single precision types, it is invalid if the sequence of components gets
larger than 3.

When a vertex shader input variable declared using a 16- or 32-bit scalar or
vector data type is assigned a location, its value(s) are taken from the
components of the input attribute specified with the corresponding
sname:VkVertexInputAttributeDescription::pname:location.
The components used depend on the type of variable and the code:Component
decoration specified in the variable declaration, as identified in
<<fxvertex-attrib-components>>.
Any 16-bit or 32-bit scalar or vector input will consume a single location.
For 16-bit and 32-bit data types, missing components are filled in with
default values as described <<fxvertex-input-extraction,below>>.


[[fxvertex-attrib-components]]
.Input attribute components accessed by 16-bit and 32-bit input variables
[width="65%",cols="<5,<3,<3",options="header"]
|====
| 16-bit or 32-bit data type | code:Component decoration | Components consumed
| scalar                     | 0 or unspecified             | (x, o, o, o)
| scalar                     | 1                            | (o, y, o, o)
| scalar                     | 2                            | (o, o, z, o)
| scalar                     | 3                            | (o, o, o, w)
| two-component vector       | 0 or unspecified             | (x, y, o, o)
| two-component vector       | 1                            | (o, y, z, o)
| two-component vector       | 2                            | (o, o, z, w)
| three-component vector     | 0 or unspecified             | (x, y, z, o)
| three-component vector     | 1                            | (o, y, z, w)
| four-component vector      | 0 or unspecified             | (x, y, z, w)
|====

Components indicated by "`o`" are available for use by other input variables
which are sourced from the same attribute, and if used, are either filled
with the corresponding component from the input format (if present), or the
default value.

When a vertex shader input variable declared using a 32-bit floating point
matrix type is assigned a location _i_, its values are taken from
consecutive input attributes starting with the corresponding
sname:VkVertexInputAttributeDescription::pname:location.
Such matrices are treated as an array of column vectors with values taken
from the input attributes identified in <<fxvertex-attrib-matrix>>.
The sname:VkVertexInputAttributeDescription::pname:format must: be specified
with a elink:VkFormat that corresponds to the appropriate type of column
vector.
The code:Component decoration must: not be used with matrix types.

[[fxvertex-attrib-matrix]]
.Input attributes accessed by 32-bit input matrix variables
[width="100%",cols="<10%,<24%,<21%,<45%",options="header"]
|====
| Data type     | Column vector type        | Locations consumed    | Components consumed
| mat2          | two-component vector      | i, i+1                | (x, y, o, o), (x, y, o, o)
| mat2x3        | three-component vector    | i, i+1                | (x, y, z, o), (x, y, z, o)
| mat2x4        | four-component vector     | i, i+1                | (x, y, z, w), (x, y, z, w)
| mat3x2        | two-component vector      | i, i+1, i+2           | (x, y, o, o), (x, y, o, o), (x, y, o, o)
| mat3          | three-component vector    | i, i+1, i+2           | (x, y, z, o), (x, y, z, o), (x, y, z, o)
| mat3x4        | four-component vector     | i, i+1, i+2           | (x, y, z, w), (x, y, z, w), (x, y, z, w)
| 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)
| 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)
| 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)
|====

Components indicated by "`o`" are available for use by other input variables
which are sourced from the same attribute, and if used, are either filled
with the corresponding component from the input (if present), or the default
value.

When a vertex shader input variable declared using a scalar or vector 64-bit
data type is assigned a location _i_, its values are taken from consecutive
input attributes starting with the corresponding
sname:VkVertexInputAttributeDescription::pname:location.
The locations and components used depend on the type of variable and the
code:Component decoration specified in the variable declaration, as
identified in <<fxvertex-attrib-double>>.
For 64-bit data types, no default attribute values are provided.
Input variables must: not use more components than provided by the
attribute.
Input attributes which have one- or two-component 64-bit formats will
consume a single location.
Input attributes which have three- or four-component 64-bit formats will
consume two consecutive locations.
A 64-bit scalar data type will consume two components, and a 64-bit
two-component vector data type will consume all four components available
within a location.
A three- or four-component 64-bit data type must: not specify a component.
A three-component 64-bit data type will consume all four components of the
first location and components 0 and 1 of the second location.
This leaves components 2 and 3 available for other component-qualified
declarations.
A four-component 64-bit data type will consume all four components of the
first location and all four components of the second location.
It is invalid for a scalar or two-component 64-bit data type to specify a
component of 1 or 3.

[[fxvertex-attrib-double]]
.Input attribute locations and components accessed by 64-bit input variables
[width="100%",cols="<18%,^12%,<25%,^14%,^18%,<13%",options="header"]
|====
^.^| Input format | Locations consumed
        ^.^| 64-bit data type   |code:Location decoration |code:Component decoration ^| 32-bit components consumed
| R64          | i
        | scalar                  | i                         | 0 or unspecified           | (x, y, -, -)
.3+<.^| R64G64 .3+^.^| i
        | scalar                  | i                         | 0 or unspecified           | (x, y, o, o)
        | scalar                  | i                         | 2                          | (o, o, z, w)
        | two-component vector    | i                         | 0 or unspecified           | (x, y, z, w)
.5+<.^| R64G64B64 .5+^.^| i, i+1
        | scalar                  | i                         | 0 or unspecified           | (x, y, o, o), (o, o, -, -)
        | scalar                  | i                         | 2                          | (o, o, z, w), (o, o, -, -)
        | scalar                  | i+1                       | 0 or unspecified           | (o, o, o, o), (x, y, -, -)
        | two-component vector    | i                         | 0 or unspecified           | (x, y, z, w), (o, o, -, -)
        | three-component vector  | i                         | unspecified                | (x, y, z, w), (x, y, -, -)
.8+<.^| R64G64B64A64 .8+^.^| i, i+1
        | scalar                  | i                         | 0 or unspecified           | (x, y, o, o), (o, o, o, o)
        | scalar                  | i                         | 2                          | (o, o, z, w), (o, o, o, o)
        | scalar                  | i+1                       | 0 or unspecified           | (o, o, o, o), (x, y, o, o)
        | scalar                  | i+1                       | 2                          | (o, o, o, o), (o, o, z, w)
        | two-component vector    | i                         | 0 or unspecified           | (x, y, z, w), (o, o, o, o)
        | two-component vector    | i+1                       | 0 or unspecified           | (o, o, o, o), (x, y, z, w)
        | three-component vector  | i                         | unspecified                | (x, y, z, w), (x, y, o, o)
        | four-component vector   | i                         | unspecified                | (x, y, z, w), (x, y, z, w)
|====

Components indicated by "`o`" are available for use by other input variables
which are sourced from the same attribute.
Components indicated by "`-`" are not available for input variables as there
are no default values provided for 64-bit data types, and there is no data
provided by the input format.

When a vertex shader input variable declared using a 64-bit floating-point
matrix type is assigned a location _i_, its values are taken from
consecutive input attribute locations.
Such matrices are treated as an array of column vectors with values taken
from the input attributes as shown in <<fxvertex-attrib-double>>.
Each column vector starts at the location immediately following the last
location of the previous column vector.
The number of attributes and components assigned to each matrix is
determined by the matrix dimensions and ranges from two to eight locations.

When a vertex shader input variable declared using an array type is assigned
a location, its values are taken from consecutive input attributes starting
with the corresponding
sname:VkVertexInputAttributeDescription::pname:location.
The number of attributes and components assigned to each element are
determined according to the data type of the array elements and
code:Component decoration (if any) specified in the declaration of the
array, as described above.
Each element of the array, in order, is assigned to consecutive locations,
but all at the same specified component within each location.

Only input variables declared with the data types and component decorations
as specified above are supported.
_Location aliasing_ is causing two variables to have the same location
number.
_Component aliasing_ is assigning the same (or overlapping) component number
for two location aliases.
Location aliasing is allowed only if it does not cause component aliasing.
Further, when location aliasing, the aliases sharing the location must: all
have the same SPIR-V floating-point component type or all have the same
width integer-type components.


[[fxvertex-input]]
== Vertex Input Description

Applications specify vertex input attribute and vertex input binding
descriptions as part of graphics pipeline creation by setting the
slink:VkGraphicsPipelineCreateInfo::pname:pVertexInputState pointer to a
slink:VkPipelineVertexInputStateCreateInfo structure.
ifdef::VK_EXT_vertex_input_dynamic_state[]
Alternatively, if the graphics pipeline is created with the
ename:VK_DYNAMIC_STATE_VERTEX_INPUT_EXT dynamic state enabled, then the
vertex input attribute and vertex input binding descriptions are specified
dynamically with flink:vkCmdSetVertexInputEXT, and the
slink:VkGraphicsPipelineCreateInfo::pname:pVertexInputState pointer is
ignored.
endif::VK_EXT_vertex_input_dynamic_state[]

[open,refpage='VkPipelineVertexInputStateCreateInfo',desc='Structure specifying parameters of a newly created pipeline vertex input state',type='structs']
--
The sname:VkPipelineVertexInputStateCreateInfo structure is defined as:

include::{generated}/api/structs/VkPipelineVertexInputStateCreateInfo.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to a structure extending this
    structure.
  * pname:flags is reserved for future use.
  * pname:vertexBindingDescriptionCount is the number of vertex binding
    descriptions provided in pname:pVertexBindingDescriptions.
  * pname:pVertexBindingDescriptions is a pointer to an array of
    sname:VkVertexInputBindingDescription structures.
  * pname:vertexAttributeDescriptionCount is the number of vertex attribute
    descriptions provided in pname:pVertexAttributeDescriptions.
  * pname:pVertexAttributeDescriptions is a pointer to an array of
    sname:VkVertexInputAttributeDescription structures.

.Valid Usage
****
  * [[VUID-VkPipelineVertexInputStateCreateInfo-vertexBindingDescriptionCount-00613]]
    pname:vertexBindingDescriptionCount must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-VkPipelineVertexInputStateCreateInfo-vertexAttributeDescriptionCount-00614]]
    pname:vertexAttributeDescriptionCount must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
  * [[VUID-VkPipelineVertexInputStateCreateInfo-binding-00615]]
    For every pname:binding specified by each element of
    pname:pVertexAttributeDescriptions, a
    sname:VkVertexInputBindingDescription must: exist in
    pname:pVertexBindingDescriptions with the same value of pname:binding
  * [[VUID-VkPipelineVertexInputStateCreateInfo-pVertexBindingDescriptions-00616]]
    All elements of pname:pVertexBindingDescriptions must: describe distinct
    binding numbers
  * [[VUID-VkPipelineVertexInputStateCreateInfo-pVertexAttributeDescriptions-00617]]
    All elements of pname:pVertexAttributeDescriptions must: describe
    distinct attribute locations
****

include::{generated}/validity/structs/VkPipelineVertexInputStateCreateInfo.txt[]
--

[open,refpage='VkPipelineVertexInputStateCreateFlags',desc='Reserved for future use',type='flags']
--
include::{generated}/api/flags/VkPipelineVertexInputStateCreateFlags.txt[]

tname:VkPipelineVertexInputStateCreateFlags is a bitmask type for setting a
mask, but is currently reserved for future use.
--

[open,refpage='VkVertexInputBindingDescription',desc='Structure specifying vertex input binding description',type='structs']
--
Each vertex input binding is specified by the
sname:VkVertexInputBindingDescription structure, defined as:

include::{generated}/api/structs/VkVertexInputBindingDescription.txt[]

  * pname:binding is the binding number that this structure describes.
  * pname:stride is the byte stride between consecutive elements within the
    buffer.
  * pname:inputRate is a elink:VkVertexInputRate value specifying whether
    vertex attribute addressing is a function of the vertex index or of the
    instance index.

.Valid Usage
****
  * [[VUID-VkVertexInputBindingDescription-binding-00618]]
    pname:binding must: be less than
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-VkVertexInputBindingDescription-stride-00619]]
    pname:stride must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindingStride
ifdef::VK_KHR_portability_subset[]
  * [[VUID-VkVertexInputBindingDescription-stride-04456]]
    If the `apiext:VK_KHR_portability_subset` extension is enabled,
    pname:stride must: be a multiple of, and at least as large as,
    slink:VkPhysicalDevicePortabilitySubsetPropertiesKHR::pname:minVertexInputBindingStrideAlignment
endif::VK_KHR_portability_subset[]
****

include::{generated}/validity/structs/VkVertexInputBindingDescription.txt[]
--

[open,refpage='VkVertexInputRate',desc='Specify rate at which vertex attributes are pulled from buffers',type='enums']
--
Possible values of slink:VkVertexInputBindingDescription::pname:inputRate,
specifying the rate at which vertex attributes are pulled from buffers, are:

include::{generated}/api/enums/VkVertexInputRate.txt[]

  * ename:VK_VERTEX_INPUT_RATE_VERTEX specifies that vertex attribute
    addressing is a function of the vertex index.
  * ename:VK_VERTEX_INPUT_RATE_INSTANCE specifies that vertex attribute
    addressing is a function of the instance index.
--

[open,refpage='VkVertexInputAttributeDescription',desc='Structure specifying vertex input attribute description',type='structs']
--
Each vertex input attribute is specified by the
sname:VkVertexInputAttributeDescription structure, defined as:

include::{generated}/api/structs/VkVertexInputAttributeDescription.txt[]

  * pname:location is the shader input location number for this attribute.
  * pname:binding is the binding number which this attribute takes its data
    from.
  * pname:format is the size and type of the vertex attribute data.
  * pname:offset is a byte offset of this attribute relative to the start of
    an element in the vertex input binding.

.Valid Usage
****
  * [[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
ifdef::VK_KHR_portability_subset[]
  * [[VUID-VkVertexInputAttributeDescription-vertexAttributeAccessBeyondStride-04457]]
    If the `apiext:VK_KHR_portability_subset` extension is enabled, and
    slink:VkPhysicalDevicePortabilitySubsetFeaturesKHR::pname:vertexAttributeAccessBeyondStride
    is ename:VK_FALSE, the sum of pname:offset plus the size of the vertex
    attribute data described by pname:format must: not be greater than
    pname:stride in the slink:VkVertexInputBindingDescription referenced in
    pname:binding
endif::VK_KHR_portability_subset[]
****

include::{generated}/validity/structs/VkVertexInputAttributeDescription.txt[]
--

ifdef::VK_EXT_vertex_input_dynamic_state[]
[open,refpage='vkCmdSetVertexInputEXT',desc='Set the vertex input state dynamically for a command buffer',type='protos']
--
To <<pipelines-dynamic-state, dynamically set>> the vertex input attribute
and vertex input binding descriptions, call:

include::{generated}/api/protos/vkCmdSetVertexInputEXT.txt[]

  * pname:commandBuffer is the command buffer into which the command will be
    recorded.
  * pname:vertexBindingDescriptionCount is the number of vertex binding
    descriptions provided in pname:pVertexBindingDescriptions.
  * pname:pVertexBindingDescriptions is a pointer to an array of
    sname:VkVertexInputBindingDescription2EXT structures.
  * pname:vertexAttributeDescriptionCount is the number of vertex attribute
    descriptions provided in pname:pVertexAttributeDescriptions.
  * pname:pVertexAttributeDescriptions is a pointer to an array of
    sname:VkVertexInputAttributeDescription2EXT structures.

This command sets the vertex input attribute and vertex input binding
descriptions state for subsequent drawing commands when the graphics
pipeline is created with ename:VK_DYNAMIC_STATE_VERTEX_INPUT_EXT set in
slink:VkPipelineDynamicStateCreateInfo::pname:pDynamicStates.
Otherwise, this state is specified by the
slink:VkGraphicsPipelineCreateInfo::pname:pVertexInputState values used to
create the currently active pipeline.

ifdef::VK_EXT_extended_dynamic_state[]
If the bound pipeline state object was also created with the
ename:VK_DYNAMIC_STATE_VERTEX_INPUT_BINDING_STRIDE_EXT dynamic state
enabled, then flink:vkCmdBindVertexBuffers2EXT can be used instead of
fname:vkCmdSetVertexInputEXT to dynamically set the stride.
endif::VK_EXT_extended_dynamic_state[]

.Valid Usage
****
  * [[VUID-vkCmdSetVertexInputEXT-None-04790]]
    The <<features-vertexInputDynamicState, vertexInputDynamicState>>
    feature must: be enabled
  * [[VUID-vkCmdSetVertexInputEXT-vertexBindingDescriptionCount-04791]]
    pname:vertexBindingDescriptionCount must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-vkCmdSetVertexInputEXT-vertexAttributeDescriptionCount-04792]]
    pname:vertexAttributeDescriptionCount must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
  * [[VUID-vkCmdSetVertexInputEXT-binding-04793]]
    For every pname:binding specified by each element of
    pname:pVertexAttributeDescriptions, a
    sname:VkVertexInputBindingDescription2EXT must: exist in
    pname:pVertexBindingDescriptions with the same value of pname:binding
  * [[VUID-vkCmdSetVertexInputEXT-pVertexBindingDescriptions-04794]]
    All elements of pname:pVertexBindingDescriptions must: describe distinct
    binding numbers
  * [[VUID-vkCmdSetVertexInputEXT-pVertexAttributeDescriptions-04795]]
    All elements of pname:pVertexAttributeDescriptions must: describe
    distinct attribute locations
****

include::{generated}/validity/protos/vkCmdSetVertexInputEXT.txt[]
--

[open,refpage='VkVertexInputBindingDescription2EXT',desc='Structure specifying the extended vertex input binding description',type='structs']
--
The sname:VkVertexInputBindingDescription2EXT structure is defined as:

include::{generated}/api/structs/VkVertexInputBindingDescription2EXT.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to a structure extending this
    structure.
  * pname:binding is the binding number that this structure describes.
  * pname:stride is the byte stride between consecutive elements within the
    buffer.
  * pname:inputRate is a elink:VkVertexInputRate value specifying whether
    vertex attribute addressing is a function of the vertex index or of the
    instance index.
ifdef::VK_EXT_vertex_attribute_divisor[]
  * pname:divisor is the number of successive instances that will use the
    same value of the vertex attribute when instanced rendering is enabled.
    This member can: be set to a value other than `1` if the
    <<features-vertexAttributeInstanceRateDivisor,
    vertexAttributeInstanceRateDivisor>> feature is enabled.
    For example, if the divisor is N, the same vertex attribute will be
    applied to N successive instances before moving on to the next vertex
    attribute.
    The maximum value of pname: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.
endif::VK_EXT_vertex_attribute_divisor[]
ifndef::VK_EXT_vertex_attribute_divisor[]
  * pname:divisor must: be set to `1`
endif::VK_EXT_vertex_attribute_divisor[]

.Valid Usage
****
  * [[VUID-VkVertexInputBindingDescription2EXT-binding-04796]]
    pname:binding must: be less than
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-VkVertexInputBindingDescription2EXT-stride-04797]]
    pname:stride must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindingStride
  * [[VUID-VkVertexInputBindingDescription2EXT-divisor-04798]]
    If the <<features-vertexAttributeInstanceRateZeroDivisor,
    vertexAttributeInstanceRateZeroDivisor>> feature is not enabled,
    pname:divisor must: not be `0`
  * [[VUID-VkVertexInputBindingDescription2EXT-divisor-04799]]
    If the <<features-vertexAttributeInstanceRateDivisor,
    vertexAttributeInstanceRateDivisor>> feature is not enabled,
    pname:divisor must: be `1`
  * [[VUID-VkVertexInputBindingDescription2EXT-divisor-06226]]
    pname:divisor must: be a value between `0` and
    sname:VkPhysicalDeviceVertexAttributeDivisorPropertiesEXT::pname:maxVertexAttribDivisor,
    inclusive
  * [[VUID-VkVertexInputBindingDescription2EXT-divisor-06227]]
    If pname:divisor is not `1` then pname:inputRate must: be of type
    ename:VK_VERTEX_INPUT_RATE_INSTANCE
****

include::{generated}/validity/structs/VkVertexInputBindingDescription2EXT.txt[]
--

[open,refpage='VkVertexInputAttributeDescription2EXT',desc='Structure specifying the extended vertex input attribute description',type='structs']
--
The sname:VkVertexInputAttributeDescription2EXT structure is defined as:

include::{generated}/api/structs/VkVertexInputAttributeDescription2EXT.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to a structure extending this
    structure.
  * pname:location is the shader input location number for this attribute.
  * pname:binding is the binding number which this attribute takes its data
    from.
  * pname:format is the size and type of the vertex attribute data.
  * pname:offset is a byte offset of this attribute relative to the start of
    an element in the vertex input binding.

.Valid Usage
****
  * [[VUID-VkVertexInputAttributeDescription2EXT-location-06228]]
    pname:location must: be less than
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributes
  * [[VUID-VkVertexInputAttributeDescription2EXT-binding-06229]]
    pname:binding must: be less than
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-VkVertexInputAttributeDescription2EXT-offset-06230]]
    pname:offset must: be less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputAttributeOffset
  * [[VUID-VkVertexInputAttributeDescription2EXT-format-04805]]
    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
ifdef::VK_KHR_portability_subset[]
  * [[VUID-VkVertexInputAttributeDescription2EXT-vertexAttributeAccessBeyondStride-04806]]
    If the `apiext:VK_KHR_portability_subset` extension is enabled, and
    slink:VkPhysicalDevicePortabilitySubsetFeaturesKHR::pname:vertexAttributeAccessBeyondStride
    is ename:VK_FALSE, the sum of pname:offset plus the size of the vertex
    attribute data described by pname:format must: not be greater than
    pname:stride in the slink:VkVertexInputBindingDescription2EXT referenced
    in pname:binding
endif::VK_KHR_portability_subset[]
****

include::{generated}/validity/structs/VkVertexInputAttributeDescription2EXT.txt[]
--
endif::VK_EXT_vertex_input_dynamic_state[]

[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 drawing
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 drawing
commands.
ifdef::VK_EXT_robustness2[]
If the <<features-nullDescriptor,nullDescriptor>> feature is enabled,
elements of pname:pBuffers can: be dlink:VK_NULL_HANDLE, and can: be used by
the vertex shader.
If a vertex input attribute is bound to a vertex input binding that is
dlink:VK_NULL_HANDLE, the values taken from memory are considered to be
zero, and missing G, B, or A components are
<<fxvertex-input-extraction,filled with [eq]#(0,0,1)#>>.
endif::VK_EXT_robustness2[]

.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
  * [[VUID-vkCmdBindVertexBuffers-pBuffers-04001]]
    If the <<features-nullDescriptor,nullDescriptor>> feature is not
    enabled, all elements of pname:pBuffers must: not be
    dlink:VK_NULL_HANDLE
ifdef::VK_EXT_robustness2[]
  * [[VUID-vkCmdBindVertexBuffers-pBuffers-04002]]
    If an element of pname:pBuffers is dlink:VK_NULL_HANDLE, then the
    corresponding element of pname:pOffsets must: be zero
endif::VK_EXT_robustness2[]
****

include::{generated}/validity/protos/vkCmdBindVertexBuffers.txt[]
--

ifdef::VK_EXT_extended_dynamic_state[]
[open,refpage='vkCmdBindVertexBuffers2EXT',desc='Bind vertex buffers to a command buffer and dynamically set strides',type='protos']
--
Alternatively, to bind vertex buffers, along with their sizes and strides,
to a command buffer for use in subsequent drawing commands, call:

include::{generated}/api/protos/vkCmdBindVertexBuffers2EXT.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.
  * pname:pSizes is `NULL` or a pointer to an array of the size in bytes of
    vertex data bound from pname:pBuffers.
  * pname:pStrides is `NULL` or a pointer to an array of buffer strides.

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].
If pname:pSizes is not `NULL` then pname:pSizes[i] specifies the bound size
of the vertex buffer starting from the corresponding elements of
pname:pBuffers[i] plus pname:pOffsets[i].
All vertex input attributes that use each of these bindings will use these
updated addresses in their address calculations for subsequent drawing
commands.
ifdef::VK_EXT_robustness2[]
If the <<features-nullDescriptor,nullDescriptor>> feature is enabled,
elements of pname:pBuffers can: be dlink:VK_NULL_HANDLE, and can: be used by
the vertex shader.
If a vertex input attribute is bound to a vertex input binding that is
dlink:VK_NULL_HANDLE, the values taken from memory are considered to be
zero, and missing G, B, or A components are
<<fxvertex-input-extraction,filled with [eq]#(0,0,1)#>>.
endif::VK_EXT_robustness2[]

This command also <pipelines-dynamic-state, dynamically sets>> the byte
strides between consecutive elements within buffer pname:pBuffers[i] to the
corresponding pname:pStrides[i] value when the graphics pipeline is created
with ename:VK_DYNAMIC_STATE_VERTEX_INPUT_BINDING_STRIDE_EXT set in
slink:VkPipelineDynamicStateCreateInfo::pname:pDynamicStates.
Otherwise, strides are specified by the
sname:VkVertexInputBindingDescription::pname:stride values used to create
the currently active pipeline.

ifdef::VK_EXT_vertex_input_dynamic_state[]
If the bound pipeline state object was also created with the
ename:VK_DYNAMIC_STATE_VERTEX_INPUT_EXT dynamic state enabled then
flink:vkCmdSetVertexInputEXT can: be used instead of
fname:vkCmdBindVertexBuffers2EXT to set the stride.
endif::VK_EXT_vertex_input_dynamic_state[]

.Valid Usage
****
  * [[VUID-vkCmdBindVertexBuffers2EXT-firstBinding-03355]]
    pname:firstBinding must: be less than
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-vkCmdBindVertexBuffers2EXT-firstBinding-03356]]
    The sum of pname:firstBinding and pname:bindingCount must: be less than
    or equal to sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindings
  * [[VUID-vkCmdBindVertexBuffers2EXT-pOffsets-03357]]
    All elements of pname:pOffsets must: be less than the size of the
    corresponding element in pname:pBuffers
  * [[VUID-vkCmdBindVertexBuffers2EXT-pSizes-03358]]
    If pname:pSizes is not `NULL`, all elements of pname:pOffsets plus
    pname:pSizes must: be less than or equal to the size of the
    corresponding element in pname:pBuffers
  * [[VUID-vkCmdBindVertexBuffers2EXT-pBuffers-03359]]
    All elements of pname:pBuffers must: have been created with the
    ename:VK_BUFFER_USAGE_VERTEX_BUFFER_BIT flag
  * [[VUID-vkCmdBindVertexBuffers2EXT-pBuffers-03360]]
    Each element of pname:pBuffers that is non-sparse must: be bound
    completely and contiguously to a single sname:VkDeviceMemory object
  * [[VUID-vkCmdBindVertexBuffers2EXT-pBuffers-04111]]
    If the <<features-nullDescriptor,nullDescriptor>> feature is not
    enabled, all elements of pname:pBuffers must: not be
    dlink:VK_NULL_HANDLE
ifdef::VK_EXT_robustness2[]
  * [[VUID-vkCmdBindVertexBuffers2EXT-pBuffers-04112]]
    If an element of pname:pBuffers is dlink:VK_NULL_HANDLE, then the
    corresponding element of pname:pOffsets must: be zero
endif::VK_EXT_robustness2[]
  * [[VUID-vkCmdBindVertexBuffers2EXT-pStrides-03362]]
    If pname:pStrides is not `NULL` each element of pname:pStrides must: be
    less than or equal to
    sname:VkPhysicalDeviceLimits::pname:maxVertexInputBindingStride
  * [[VUID-vkCmdBindVertexBuffers2EXT-pStrides-06209]]
    If pname:pStrides is not `NULL` each element of pname:pStrides must: be
    either 0 or greater than or equal to the maximum extent of all vertex
    input attributes fetched from the corresponding binding, where the
    extent is calculated as the
    slink:VkVertexInputAttributeDescription::pname:offset plus
    slink:VkVertexInputAttributeDescription::pname:format size
****

include::{generated}/validity/protos/vkCmdBindVertexBuffers2EXT.txt[]
--
endif::VK_EXT_extended_dynamic_state[]


ifdef::VK_EXT_vertex_attribute_divisor[]

[[fxvertex-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 a structure extending this
    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 be
    applied to N successive instances before moving on to the next vertex
    attribute.
    The maximum value of pname: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[]

[[fxvertex-input-address-calculation]]
== Vertex Input Address Calculation
The address of each attribute for each code:vertexIndex and
code:instanceIndex is calculated as follows:

  * Let code:attribDesc be the member of
    slink:VkPipelineVertexInputStateCreateInfo::pname:pVertexAttributeDescriptions
    with sname:VkVertexInputAttributeDescription::pname:location equal to
    the vertex input attribute number.
  * Let code:bindingDesc be the member of
    slink: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
    slink: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]]
=== Vertex Input Extraction
For each attribute, raw data is extracted starting at `attribAddress` and is
converted from the sname:VkVertexInputAttributeDescription's pname:format to
either 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.
The input variable in the shader must: be declared as a 64-bit data type if
and only if pname:format is a 64-bit data type.
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>>).
For attributes that are not 64-bit data types, each component is converted
to the format of the input variable based on its type and size (as defined
in the <<formats-definition,Format Definition>> section for each
elink:VkFormat), using the appropriate equations in <<fundamentals-fp16,
16-Bit Floating-Point Numbers>>, <<fundamentals-fp11,Unsigned 11-Bit
Floating-Point Numbers>>, <<fundamentals-fp10,Unsigned 10-Bit Floating-Point
Numbers>>, <<fundamentals-fixedconv,Fixed-Point Data Conversion>>, and
<<textures-sexp-RGB,Shared Exponent to RGB>>.
Signed integer components smaller than 32 bits are sign-extended.
Attributes that are not 64-bit data types are expanded to four components in
the same way as described in <<textures-conversion-to-rgba,conversion to
RGBA>>.
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.