The createBindGroupLayout()
method of the GPUDevice
interface creates a GPUBindGroupLayout
that defines the structure and purpose of related GPU resources such as buffers that will be used in a pipeline, and is used as a template when creating GPUBindGroup
s.
createBindGroupLayout(descriptor)
An entry object includes the following properties:
binding
-
A number representing a unique identifier for this particular entry, which matches the binding
value of a corresponding GPUBindGroup
entry. In addition, it matches the n
index value of the corresponding @binding(n)
attribute in the shader (GPUShaderModule
) used in the related pipeline.
visibility
-
One or more bitwise flags defining the shader stages that a GPUBindGroup
entry corresponding to this entry will be visible to. Possible values are:
-
GPUShaderStage.COMPUTE
: The bind group entry will be accessible to compute shaders. -
GPUShaderStage.FRAGMENT
: The bind group entry will be accessible to fragment shaders. -
GPUShaderStage.VERTEX
: The bind group entry will be accessible to vertex shaders.
Note that multiple stages can be specified by separating values with pipe symbols, for example:
visibility: GPUShaderStage.FRAGMENT | GPUShaderStage.VERTEX;
- "Resource layout object"
-
An object that defines the required binding resource type and structure of the GPUBindGroup
entry corresponding to this entry. This property can be one of buffer
, externalTexture
, sampler
, storageTexture
, or texture
, the object structures of which are described in the next section.
The resource layout object can be one of the following (see also GPUDevice.createBindGroup()
for details of how the required resources for each entry are structured):
-
buffer
: Indicates that the corresponding GPUBindGroup
entry will be a GPUBufferBinding
object, which contains a GPUBuffer
plus offset
and size
values. A buffer
resource layout object can contain the following properties: -
hasDynamicOffset
Optional
-
A boolean. If set to true
, it indicates that this binding requires a dynamic offset, for example as set during a GPURenderPassEncoder.setBindGroup()
call. If omitted, hasDynamicOffset
defaults to false
.
-
minBindingSize
Optional
-
A number indicating the minimum allowed size, in bytes, of bound buffers. If omitted, minBindingSize
defaults to 0. If the value is 0, minimum buffer size is ignored during pipeline creation and is instead validated by issued draw/dispatch commands.
-
type
Optional
-
An enumerated value specifying the required type for GPUBuffer
s bound to this binding (see GPUDevice.createBuffer()
for more information on buffer types). Possible values are:
-
"read-only-storage"
: A read-only buffer created with a usage
of GPUBufferUsage.STORAGE
. -
"storage"
: A writable buffer created with a usage
of GPUBufferUsage.STORAGE
. -
"uniform"
: A buffer created with a usage
of GPUBufferUsage.UNIFORM
.
If omitted, type
defaults to "uniform"
.
-
externalTexture
: Indicates that the corresponding GPUBindGroup
entry will be a GPUExternalTexture
object. An externalTexture
resource layout object is empty — {}
. -
sampler
: Indicates that the corresponding GPUBindGroup
entry will be a GPUSampler
object. A sampler
resource layout object can contain the following properties: -
type
Optional
-
An enumerated value specifying the required type for GPUSampler
s bound to this binding (see GPUDevice.createSampler()
for more information on sampler types). Possible values are:
-
"comparison"
: A comparison sampler. -
"filtering"
: A filtering sampler. -
"non-filtering"
: A non-filtering sampler.
If omitted, type
defaults to "filtering"
.
-
storageTexture
: Indicates that the corresponding GPUBindGroup
entry will be a GPUTextureView
object. A storageTexture
resource layout object can contain the following properties: -
access
Optional
-
An enumerated value specifying whether texture views bound to this binding will be bound for read and/or write access. Possible values are currently "write-only"
and undefined
, with the intention to add more access modes in the future. If omitted, the default value is "write-only"
.
format
-
An enumerated value specifying the required format of texture views bound to this binding. See the specification's Texture Formats section for all the available format
values.
-
viewDimension
Optional
-
An enumerated value specifying the required dimension for texture views bound to this binding. Possible values are:
-
"1d"
: The texture is viewed as a one-dimensional image. -
"2d"
: The texture is viewed as a single two-dimensional image. -
"2d-array"
: The texture is viewed as an array of two-dimensional images. -
"cube"
: The texture is viewed as a cubemap. The view has 6 array layers, corresponding to the [+X, -X, +Y, -Y, +Z, -Z]
faces of the cube. Sampling is done seamlessly across the faces of the cubemap. -
"cube-array"
: The texture is viewed as a packed array of n
cubemaps, each with 6 array layers corresponding to the [+X, -X, +Y, -Y, +Z, -Z]
faces of the cube. Sampling is done seamlessly across the faces of the cubemaps. -
"3d"
: The texture is viewed as a three-dimensional image.
If omitted, viewDimension
defaults to "2d"
.
-
texture
: Indicates that the corresponding GPUBindGroup
entry will be a GPUTextureView
object. A texture
resource layout object can contain the following properties: -
multisampled
Optional
-
A boolean. A value of true
indicates that texture views bound to this binding must be multi-sampled. If omitted, multisampled
defaults to false
.
-
sampleType
Optional
-
An enumerated value specifying the sample type required for texture views bound to this binding (see GPUDevice.createTexture()
for more information on texture view types). Possible values are:
"depth"
"float"
"sint"
"uint"
"unfilterable-float"
If omitted, sampleType
defaults to "float"
.
-
viewDimension
Optional
-
An enumerated value specifying the required dimension for texture views bound to this binding. Possible and default values are the same as for storageTexture
resource layout objects — see above.
A GPUBindGroupLayout
object instance.
The following criteria must be met when calling createBindGroupLayout()
, otherwise a GPUValidationError
is generated and an invalid GPUBindGroupLayout
object is returned:
- Each entry's
binding
value is unique. - Each entry's
binding
value is less than the GPUDevice
's maxBindingsPerBindGroup
limit. - The number of entries does not exceed the binding slot limits.
- Only 1 resource layout object is defined per entry.
- If an entry's
visibility
includes GPUShaderStage.VERTEX
: - If its resource layout object is a
buffer
, its type
is not "storage"
. - Its resource layout object is not a
storageTexture
.
- If an entry's resource layout object is a
texture
, and its multisampled
value is true
: - Its
viewDimension
is "2d"
. - Its
sampleType
is not "float"
.
- If an entry's resource layout object is a
storageTexture
: - Its
viewDimension
is not "cube"
or "cube-array"
. - Its
format
is a format that supports storage usage.
Our basic compute demo shows an example of creating a bind group layout and then using that as a template when creating a bind group.
const bindGroupLayout = device.createBindGroupLayout({
entries: [
{
binding: 0,
visibility: GPUShaderStage.COMPUTE,
buffer: {
type: "storage",
},
},
],
});
const bindGroup = device.createBindGroup({
layout: bindGroupLayout,
entries: [
{
binding: 0,
resource: {
buffer: output,
},
},
],
});