The createRenderPipeline()
method of the GPUDevice
interface creates a GPURenderPipeline
that can control the vertex and fragment shader stages and be used in a GPURenderPassEncoder
or GPURenderBundleEncoder
.
createRenderPipeline(descriptor)
The depthStencil
object can contain the following properties:
-
depthBias
Optional
-
A number representing a constant depth bias that is added to each fragment. If omitted, depthBias
defaults to 0.
-
depthBiasClamp
Optional
-
A number representing the maximum depth bias of a fragment. If omitted, depthBiasClamp
defaults to 0.
-
depthBiasSlopeScale
Optional
-
A number representing a depth bias that scales with the fragment's slope. If omitted, depthBiasSlopeScale
defaults to 0.
depthCompare
-
An enumerated value specifying the comparison operation used to test fragment depths against depthStencilAttachment
depth values. Possible values are:
-
"never"
: Comparison tests never pass. -
"less"
: A provided value passes the comparison test if it is less than the sampled value. -
"equal"
: A provided value passes the comparison test if it is equal to the sampled value. -
"less-equal"
: A provided value passes the comparison test if it is less than or equal to the sampled value. -
"greater"
: A provided value passes the comparison test if it is greater than the sampled value. -
"not-equal"
: A provided value passes the comparison test if it is not equal to the sampled value. -
"greater-equal"
: A provided value passes the comparison test if it is greater than or equal to the sampled value. -
"always"
: Comparison tests always pass.
depthWriteEnabled
-
A boolean. A value of true
specifies that the GPURenderPipeline
can modify depthStencilAttachment
depth values after creation. Setting it to false
means it cannot.
format
-
An enumerated value specifying the depthStencilAttachment
format that the GPURenderPipeline
will be compatible with. See the specification's Texture Formats section for all the available format
values.
-
stencilBack
Optional
-
An object that defines how stencil comparisons and operations are performed for back-facing primitives. Its properties can include:
-
compare
Optional
-
An enumerated value specifying the comparison operation used when testing fragments against depthStencilAttachment
stencil values. Possible values are the same as for the depthCompare
property; see above. If omitted, compare
defaults to "always"
.
-
depthFailOp
Optional
-
An enumerated value specifying the stencil operation performed if the fragment depth comparison described by depthCompare
fails. Possible values are:
-
"decrement-clamp"
: Decrement the current render state stencil value, clamping it to 0. -
"decrement-wrap"
: Decrement the current render state stencil value, wrapping it to the maximum representable value of the depthStencilAttachment
's stencil aspect if the value goes below 0. -
"invert"
: Bitwise-invert the current render state stencil value. -
"increment-clamp"
: Increments the current render state stencil value, clamping it to the maximum representable value of the depthStencilAttachment
's stencil aspect. -
"increment-wrap"
: Increments the current render state stencil value, wrapping it to zero if the value exceeds the maximum representable value of the depthStencilAttachment
's stencil aspect. -
"keep"
: Keep the current stencil value. -
"replace"
: Set the stencil value to the current render state stencil value. -
"zero"
: Set the stencil value to 0.
If omitted, depthFailOp
defaults to "keep"
.
Note:: The render state stencil value is initialized to 0 at the start of a render pass.
-
failOp
Optional
-
An enumerated value specifying the stencil operation performed if the fragment stencil comparison test described by compare
fails. Possible and default values are the same as for depthFailOp
.
-
passOp
Optional
-
An enumerated value specifying the stencil operation performed if the fragment stencil comparison test described by compare
passes. Possible and default values are the same as for depthFailOp
.
-
stencilFront
Optional
-
An object that defines how stencil comparisons and operations are performed for front-facing primitives. Its properties are the same as for stencilBack
.
-
stencilReadMask
Optional
-
A bitmask controlling which depthStencilAttachment
stencil value bits are read when performing stencil comparison tests. If omitted, stencilReadMask
defaults to 0xFFFFFFFF
.
-
stencilWriteMask
Optional
-
A bitmask controlling which depthStencilAttachment
stencil value bits are written to when performing stencil operations. If omitted, stencilWriteMask
defaults to 0xFFFFFFFF
.
The fragment
object contains an array of objects, each of which can contain the following properties:
-
constants
Optional
-
A sequence of record types, with the structure (id, value)
, representing override values for WGSL constants that can be overridden in the pipeline. These behave like ordered maps. In each case, the id
is a key used to identify or select the record, and the constant
is an enumerated value representing a WGSL.
Depending on which constant you want to override, the id
may take the form of the numeric ID of the constant, if one is specified, or otherwise the constant's identifier name.
A code snippet providing override values for several overridable constants might look like this:
{
constants: {
0: false,
1200: 3.0,
1300: 2.0,
width: 20,
depth: -1,
height: 15,
}
}
entryPoint
-
The name of the function in the module
that this stage will use to perform its work. The corresponding shader function must have the @fragment
attribute to be identified as this entry point. See Entry Point Declaration for more information.
module
-
A GPUShaderModule
object containing the WGSL code that this programmable stage will execute.
targets
-
an array of objects representing color states that represent configuration details for the colors output by the fragment shader stage. These objects can include the following properties:
-
blend
Optional
-
A object that describes a blend mode to be applied to the output color. blend
has two properties:
alpha
-
Describes the alpha channel value.
color
-
Describes the color value.
alpha
and color
both take an object as a value that can include the following properties:
-
dstFactor
Optional
-
An enumerated value that defines the blend factor operation to be performed on values from the target attachment. Possible values are:
"constant"
"dst"
"dst-alpha"
"one"
"one-minus-dst"
"one-minus-src"
"one-minus-src-alpha"
"one-minus-dst-alpha"
"one-minus-constant"
"src"
"src-alpha"
"src-alpha-saturated"
"zero"
If omitted, dstFactor
defaults to "zero"
.
-
operation
Optional
-
An enumerated value that defines the algorithm used to combine source and destination blend factors, to calculate the final values written to the target attachment components. Possible values are:
"add"
"max"
"min"
"reverse-subtract"
"subtract"
If omitted, operation
defaults to "add"
.
-
srcFactor
Optional
-
An enumerated value that defines the blend factor operation to be performed on values from the fragment shader. Possible values are the same as for dstFactor
. If omitted, srcFactor
defaults to "one"
.
Note: For a detailed explanation of the algorithms defined by each dstFactor
/srcFactor
and operation
enumerated value, see the Blend State section of the specification.
format
-
An enumerated value specifying the required format for output colors. See the specification's Texture Formats section for all the available format
values.
-
writeMask
Optional
-
One or more bitwise flags defining the write mask to apply to the color target state. Possible flag values are:
GPUFlagsConstant.RED
GPUFlagsConstant.GREEN
GPUFlagsConstant.BLUE
GPUFlagsConstant.ALPHA
GPUFlagsConstant.ALL
If omitted, writeMask
defaults to GPUFlagsConstant.ALL
.
Note that multiple flags can be specified by separating values with pipe symbols, for example:
writeMask: GPUFlagsConstant.RED | GPUFlagsConstant.ALPHA;
The multisample
object can contain the following properties:
-
alphaToCoverageEnabled
Optional
-
A boolean. A value of true
indicates that a fragment's alpha channel should be used to generate a sample coverage mask. If omitted, alphaToCoverageEnabled
defaults to false
.
-
count
Optional
-
A number that defines the number of samples per pixel. The pipeline will be compatible only with attachment textures (colorAttachment
s and depthStencilAttachment
s) with matching sampleCounts
(see GPUTexture
).
If omitted, count
defaults to 1.
-
mask
Optional
-
A bitmask that determines which samples are written to. If omitted, mask
defaults to 0xFFFFFFFF
.
The primitive
object can contain the following properties:
-
cullMode
Optional
-
An enumerated value that defines which polygon orientation will be culled, if any. Possible values are:
-
"back"
: Back-facing polygons are culled. -
"front"
: Front-facing polygons are culled. -
"none"
: No polygons are culled.
If omitted, cullMode
defaults to "none"
.
-
frontFace
Optional
-
An enumerated value that defines which polygons are considered front-facing. Possible values are:
-
"ccw"
: Polygons with vertices whose framebuffer coordinates are given in counter-clockwise order. -
"cw"
: Polygons with vertices whose framebuffer coordinates are given in clockwise order.
If omitted, frontFace
defaults to "ccw"
.
-
stripIndexFormat
Optional
-
An enumerated value that determines the index buffer format and primitive restart value in the case of pipelines with strip topologies ("line-strip"
or "triangle-strip"
). The primitive restart value specifies which index value indicates that a new primitive should be started rather than continuing to construct the strip with the prior indexed vertices. Possible values are:
-
"uint16"
: Indicates a byte size of 2 and a primitive restart value of 0xFFFF
. -
"uint32"
: Indicates a byte size of 4 and a primitive restart value of 0xFFFFFFFF
.
GPU primitive states that specify a strip primitive topology must specify a strip index format if they are used for indexed draws (for example, via GPURenderPassEncoder.drawIndexed()
) so that the primitive restart value that will be used is known at pipeline creation time. Pipelines with list primitive topologies ("line-list"
, "point-list"
, or "triangle-list"
) should not specify a stripIndexFormat
value. They will instead use the index format passed to, for example, GPURenderPassEncoder.setIndexBuffer()
when doing indexed rendering.
-
topology
Optional
-
An enumerated value that defines the type of primitive to be constructed from the specified vertex
inputs. Possible values are:
-
"line-list"
: Each consecutive pair of two vertices defines a line primitive. -
"line-strip"
: Each vertex after the first defines a line primitive between it and the previous vertex. -
"point-list"
: Each vertex defines a point primitive. -
"triangle-list"
: Each consecutive triplet of three vertices defines a triangle primitive. -
"triangle-strip"
: Each vertex after the first two defines a triangle primitive between it and the previous two vertices.
If omitted, topology
defaults to "triangle-list"
.
-
unclippedDepth
Optional
-
A boolean. A value of true
indicates that depth clipping is disabled. If omitted, unclippedDepth
defaults to false
. Note that to control depth clipping, the depth-clip-control
feature must be enabled in the GPUDevice
.
Note: frontFace
and cullMode
have no effect on "point-list"
, "line-list"
, or "line-strip"
topologies.
The vertex
object can contain the following properties:
-
constants
Optional
-
A sequence of record types, with the structure (id, value)
, representing override values for WGSL constants that can be overridden in the pipeline. These behave like ordered maps. In each case, the id
is a key used to identify or select the record, and the constant
is an enumerated value representing a WGSL.
Depending on which constant you want to override, the id
may take the form of the numeric ID of the constant, if one is specified, or otherwise the constant's identifier name.
A code snippet providing override values for several overridable constants might look like this:
{
constants: {
0: false,
1200: 3.0,
1300: 2.0,
width: 20,
depth: -1,
height: 15,
}
}
entryPoint
-
The name of the function in the module
that this stage will use to perform its work. The corresponding shader function must have the @vertex
attribute to be identified as this entry point. See Entry Point Declaration for more information.
module
-
A GPUShaderModule
object containing the WGSL code that this programmable stage will execute.
-
buffers
Optional
-
An array of objects, each representing the expected layout of a vertex buffer used in the pipeline. Each object can contain the following properties:
arrayStride
-
A number representing the stride, in bytes, between the different structures (e.g. vertices) inside the buffer.
attributes
-
An array of objects defining the layout of the vertex attributes within each structure. Each object has the following properties:
format
-
An enumerated value that specifies the format of the vertex. For all the available values, see the GPUVertexFormat
definition in the specification.
offset
-
A number specifying the offset, in bytes, from the beginning of the structure to the data for the attribute.
shaderLocation
-
The numeric location associated with this attribute, which will correspond with a @location
attribute declared in the WGSL code of the associated GPUShaderModule
referenced in the vertex
object's module
property.
-
stepMode
Optional
-
An enumerated value that defines whether the separate structures inside the buffer represent vertices or instances. Possible values are:
-
"instance"
: Each structure is an instance — the address is advanced by arrayStride
for each instance. -
"vertex"
: Each structure is a vertex — the address is advanced by arrayStride
for each vertex, and reset between instances.
If omitted, stepMode
defaults to "vertex"
.
A GPURenderPipeline
object instance.
The following criteria must be met when calling createRenderPipeline()
, otherwise a GPUValidationError
is generated and an invalid GPURenderPipeline
object is returned:
- For
depthStencil
objects: -
format
is a depth-or-stencil
format. - If
depthWriteEnabled
is true
or depthCompare
is not "always"
, format
has a depth component. - If
stencilFront
or stencilBack
's properties are not at their default values, format
has a stencil component.
- For
fragment
objects: -
targets.length
is less than or equal to the GPUDevice
's maxColorAttachments
limit. - For each
target
, writeMask
's numeric equivalent is less than 16. - If any of the used blend factor operations use the source alpha channel (for example
"src-alpha-saturated"
), the output has an alpha channel (that is, it must be a vec4
).
Our basic render demo provides a simple example of the construction of a valid render pipeline descriptor object, which is then used to create a GPURenderPipeline
via a createRenderPipeline()
call.
const vertexBuffers = [
{
attributes: [
{
shaderLocation: 0,
offset: 0,
format: "float32x4",
},
{
shaderLocation: 1,
offset: 16,
format: "float32x4",
},
],
arrayStride: 32,
stepMode: "vertex",
},
];
const pipelineDescriptor = {
vertex: {
module: shaderModule,
entryPoint: "vertex_main",
buffers: vertexBuffers,
},
fragment: {
module: shaderModule,
entryPoint: "fragment_main",
targets: [
{
format: navigator.gpu.getPreferredCanvasFormat(),
},
],
},
primitive: {
topology: "triangle-list",
},
layout: "auto",
};
const renderPipeline = device.createRenderPipeline(pipelineDescriptor);