GPUCommandEncoder: beginComputePass() method
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Note: This feature is available in Web Workers.
The beginComputePass() method of the GPUCommandEncoder interface starts encoding a compute pass, returning a GPUComputePassEncoder that can be used to control computation.
Syntax
beginComputePass() beginComputePass(descriptor) Parameters
descriptorOptional-
An object containing the following properties:
labelOptional-
A string providing a label that can be used to identify the object, for example in
GPUErrormessages or console warnings. timestampWritesOptional-
An array of objects defining where and when timestamp query values will be written for this pass. These objects have the following properties:
querySet-
A
GPUQuerySetof type"timestamp"that the timestamp query results will be written to. beginningOfPassWriteIndex-
A number specifying the query index in
querySetwhere the timestamp at the beginning of the render pass will be written. This is optional - if not defined, no timestamp will be written for the beginning of the pass. endOfPassWriteIndex-
A number specifying the query index in
querySetwhere the timestamp at the end of the render pass will be written. This is optional - if not defined, no timestamp will be written for the end of the pass.
Note: The
timestamp-queryfeature needs to be enabled to use timestamp queries. Timestamp query values are written in nanoseconds, but how the value is determined is implementation-defined.
Return value
A GPUComputePassEncoder object instance.
Validation
The following criteria must be met when calling beginComputePass(), otherwise a GPUValidationError is generated and an invalid GPUComputePassEncoder is returned:
Examples
In our basic compute demo, several commands are recorded via a GPUCommandEncoder. Most of these commands originate from the GPUComputePassEncoder created via beginComputePass().
// … // Create GPUCommandEncoder to encode commands to issue to the GPU const commandEncoder = device.createCommandEncoder(); // Initiate render pass const passEncoder = commandEncoder.beginComputePass(); // Issue commands passEncoder.setPipeline(computePipeline); passEncoder.setBindGroup(0, bindGroup); passEncoder.dispatchWorkgroups(Math.ceil(BUFFER_SIZE / 64)); // End the render pass passEncoder.end(); // Copy output buffer to staging buffer commandEncoder.copyBufferToBuffer( output, 0, // Source offset stagingBuffer, 0, // Destination offset BUFFER_SIZE, ); // End frame by passing array of command buffers to command queue for execution device.queue.submit([commandEncoder.finish()]); // … Specifications
| Specification |
|---|
| WebGPU # dom-gpucommandencoder-begincomputepass |
Browser compatibility
See also
- The WebGPU API