GPUBuffer

label Experimental

A string providing a label that can be used to identify the object, for example in GPUError messages or console warnings.

mapState Experimental Read only

An enumerated value representing the mapped state of the GPUBuffer.

size Experimental Read only

A number representing the length of the GPUBuffer's memory allocation, in bytes.

usage Experimental Read only

The bitwise flags representing the allowed usages of the GPUBuffer.

destroy() Experimental

Destroys the GPUBuffer.

getMappedRange() Experimental

Returns an ArrayBuffer containing the mapped contents of the GPUBuffer in the specified range.

mapAsync() Experimental

Maps the specified range of the GPUBuffer. Returns a Promise that resolves when the GPUBuffer's content is ready to be accessed with GPUBuffer.getMappedRange().

unmap() Experimental

Unmaps the mapped range of the GPUBuffer, making its contents available for use by the GPU again.

In our basic compute demo, we create an output buffer to read GPU calculations to, and a staging buffer to be mapped for JavaScript access.

const output = device.createBuffer({
  size: BUFFER_SIZE,
  usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_SRC,
});

const stagingBuffer = device.createBuffer({
  size: BUFFER_SIZE,
  usage: GPUBufferUsage.MAP_READ | GPUBufferUsage.COPY_DST,
});

Later on, once the stagingBuffer contains the results of the GPU computation, a combination of GPUBuffer methods are used to read the data back to JavaScript so that it can then be logged to the console:

• GPUBuffer.mapAsync() is used to map the GPUBuffer for reading.
• GPUBuffer.getMappedRange() is used to return an ArrayBuffer containing the GPUBuffer's contents.
• GPUBuffer.unmap() is used to unmap the GPUBuffer again, once we have read the content into JavaScript as needed.

// map staging buffer to read results back to JS
await stagingBuffer.mapAsync(
  GPUMapMode.READ,
  0, // Offset
  BUFFER_SIZE, // Length
);

const copyArrayBuffer = stagingBuffer.getMappedRange(0, BUFFER_SIZE);
const data = copyArrayBuffer.slice(0);
stagingBuffer.unmap();
console.log(new Float32Array(data));

• The WebGPU API