GPURenderBundleEncoder: drawIndexedIndirect() method

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The drawIndexedIndirect() method of the GPURenderBundleEncoder interface draws indexed primitives using parameters read from a GPUBuffer.

[!NOTE] This method is functionally identical to its equivalent on GPURenderPassEncoder — drawIndexedIndirect().

Syntax

drawIndexedIndirect(indirectBuffer, indirectOffset)

Parameters

• indirectBuffer

  • : A GPUBuffer containing the indexCount, instanceCount, firstIndex, baseVertex, and firstInstance values needed to carry out the drawing operation. The buffer must contain a tightly packed block of five 32-bit unsigned integer values representing the values (20 bytes total), given in the same order as the arguments for drawIndexed(). So for example:

    const uint32 = new Uint32Array(5);
    uint32[0] = 3; // The indexCount value
    uint32[1] = 1; // The instanceCount value
    uint32[2] = 0; // The firstIndex value
    uint32[3] = 0; // The baseVertex value
    uint32[4] = 0; // The firstInstance value
    
    // Write values into a GPUBuffer
    device.queue.writeBuffer(buffer, 0, uint32, 0, uint32.length);
    

    [!NOTE] The indirect-first-instance feature needs to be enabled for non-zero firstInstance values to be used. If the indirect-first-instance feature is not enabled and firstInstance is not zero, the drawIndexedIndirect() call will be treated as a no-op.

• indirectOffset

  • : The offset, in bytes, into indirectBuffer where the value data begins.

Return value

None (undefined).

Validation

The following criteria must be met when calling drawIndirect(), otherwise a GPUValidationError is generated and the GPURenderBundleEncoder becomes invalid:

• indirectBuffer’s usage contains the GPUBufferUsage.INDIRECT flag.
• indirectOffset + the total size specified by the value parameters in the indirectBuffer is less than or equal to the indirectBuffer’s size.
• indirectOffset is a multiple of 4.

Examples

// …

// Create GPURenderBundleEncoder
const bundleEncoder = device.createRenderBundleEncoder(descriptor);

// Set pipeline and vertex buffer
bundleEncoder.setPipeline(renderPipeline);
bundleEncoder.setVertexBuffer(0, vertexBuffer);
bundleEncoder.setIndexBuffer(indexBuffer, "uint16");

// Create drawIndexedIndirect values
const uint32 = new Uint32Array(5);
uint32[0] = 3;
uint32[1] = 1;
uint32[2] = 0;
uint32[3] = 0;
uint32[4] = 0;

// Create a GPUBuffer and write the draw values into it
const drawValues = device.createBuffer({
  size: 20,
  usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.INDIRECT,
});
device.queue.writeBuffer(drawValues, 0, uint32, 0, uint32.length);

// Draw the vertices
bundleEncoder.drawIndexedIndirect(drawValues, 0);

// End the bundle recording
const renderBundle = bundleEncoder.finish();

// …

Specifications

Browser compatibility

See also

• The WebGPU API