GPURenderBundleEncoder

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The GPURenderBundleEncoder interface of the WebGPU API is used to pre-record bundles of commands.

The command bundles are encoded by calling the methods of GPURenderBundleEncoder; once the desired commands have been encoded, they are recorded into a GPURenderBundle object instance using the GPURenderBundleEncoder.finish() method. These render bundles can then be reused across multiple render passes by passing the GPURenderBundle objects into GPURenderPassEncoder.executeBundles() calls.

In effect, this is like a partial render pass — GPURenderBundleEncoders have all the same functionality available as GPURenderPassEncoders, except that they can't begin and end occlusion queries, and can't set the scissor rect, viewport, blend constant, and stencil reference. The GPURenderBundle will inherit all these values from the GPURenderPassEncoder that executes it.

Note: Currently set vertex buffers, index buffers, bind groups, and pipeline are all cleared prior to executing a render bundle, and once the render bundle has finished executing.

Reusing pre-recoded commands can significantly improve app performance in situations where JavaScript draw call overhead is a bottleneck. Render bundles are most effective in situations where a batch of objects will be drawn the same way across multiple views or frames, with the only differences being the buffer content being used (such as updated matrix uniforms). A good example is VR rendering. Recording the rendering as a render bundle and then tweaking the view matrix and replaying it for each eye is a more efficient way to issue draw calls for both renderings of the scene.

A GPURenderBundleEncoder object instance is created via the GPUDevice.createRenderBundleEncoder() property.

Note: The methods of GPURenderBundleEncoder are functionally identical to their equivalents available on GPURenderPassEncoder, except for GPURenderBundleEncoder.finish(), which is similar in purpose to GPUCommandEncoder.finish().

Instance properties

label

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

Instance methods

draw()

Draw primitives based on the vertex buffers provided by setVertexBuffer().

drawIndexed()

Draw indexed primitives based on the vertex and index buffers provided by setVertexBuffer() and setIndexBuffer()

drawIndirect()

Draw primitives using parameters read from a GPUBuffer.

drawIndexedIndirect()

Draw indexed primitives using parameters read from a GPUBuffer.

finish()

Completes recording of the current render pass command sequence.

insertDebugMarker()

Marks a specific point in a series of encoded commands with a label.

popDebugGroup()

Ends a debug group, which is begun with a pushDebugGroup() call.

pushDebugGroup()

Begins a debug group, which is marked with a specified label, and will contain all subsequent encoded commands up until a popDebugGroup() method is invoked.

setBindGroup()

Sets the GPUBindGroup to use for subsequent render bundle commands, for a given index.

setIndexBuffer()

Sets the current GPUBuffer that will provide index data for subsequent drawing commands.

setPipeline()

Sets the GPURenderPipeline to use for this render bundle.

setVertexBuffer()

Sets the current GPUBuffer that will provide vertex data for subsequent drawing commands.

Examples

In the WebGPU Samples Animometer example, a lot of like operations are done on many different objects simultaneously. A bundle of commands is encoded using the following function:

js

function recordRenderPass(
  passEncoder: GPURenderBundleEncoder | GPURenderPassEncoder
) {
  if (settings.dynamicOffsets) {
    passEncoder.setPipeline(dynamicPipeline);
  } else {
    passEncoder.setPipeline(pipeline);
  }
  passEncoder.setVertexBuffer(0, vertexBuffer);
  passEncoder.setBindGroup(0, timeBindGroup);
  const dynamicOffsets = [0];
  for (let i = 0; i < numTriangles; ++i) {
    if (settings.dynamicOffsets) {
      dynamicOffsets[0] = i * alignedUniformBytes;
      passEncoder.setBindGroup(1, dynamicBindGroup, dynamicOffsets);
    } else {
      passEncoder.setBindGroup(1, bindGroups[i]);
    }
    passEncoder.draw(3, 1, 0, 0);
  }
}

Later on, a GPURenderBundleEncoder is created, the function is invoked, and the command bundle is recorded into a GPURenderBundle using GPURenderBundleEncoder.finish():

js

const renderBundleEncoder = device.createRenderBundleEncoder({
  colorFormats: [presentationFormat],
});
recordRenderPass(renderBundleEncoder);
const renderBundle = renderBundleEncoder.finish();

GPURenderPassEncoder.executeBundles() is then used to reuse the work across multiple render passes to improve performance. Study the example code listing for the full context.

js

// ...

return function doDraw(timestamp) {
  if (startTime === undefined) {
    startTime = timestamp;
  }
  uniformTime[0] = (timestamp - startTime) / 1000;
  device.queue.writeBuffer(uniformBuffer, timeOffset, uniformTime.buffer);

  renderPassDescriptor.colorAttachments[0].view = context
    .getCurrentTexture()
    .createView();

  const commandEncoder = device.createCommandEncoder();
  const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);

  if (settings.renderBundles) {
    passEncoder.executeBundles([renderBundle]);
  } else {
    recordRenderPass(passEncoder);
  }

  passEncoder.end();
  device.queue.submit([commandEncoder.finish()]);
};

// ...

Specifications

Specification
WebGPU
# gpurenderbundle

Browser compatibility

BCD tables only load in the browser

See also