W3cubDocs

/Web APIs

GPURenderPassEncoder: drawIndirect() method

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

The drawIndirect() method of the GPURenderPassEncoder interface draws primitives using parameters read from a GPUBuffer.

Syntax

js

drawIndirect(indirectBuffer, indirectOffset)

Parameters

indirectBuffer

A GPUBuffer containing the vertexCount, instanceCount, firstVertex, and firstInstance values needed to carry out the drawing operation. The buffer must contain a tightly packed block of four 32-bit unsigned integer values representing the values (16 bytes total), given in the same order as the arguments for GPURenderPassEncoder.draw(). So for example:

js

const uint32 = new Uint32Array(4);
uint32[0] = 3; // The vertexCount value
uint32[1] = 1; // The instanceCount value
uint32[2] = 0; // The firstVertex value
uint32[3] = 0; // The firstInstance value

// Write values into a GPUBuffer
device.queue.writeBuffer(buffer, 0, uint32, 0, uint32.length);
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 GPURenderPassEncoder becomes invalid:

  • indirectBuffer's GPUBuffer.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 GPUBuffer.size.
  • indirectOffset is a multiple of 4.

Examples

js

// ...

// Create GPURenderPassEncoder
const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);

// Set pipeline and vertex buffer
passEncoder.setPipeline(renderPipeline);
passEncoder.setVertexBuffer(0, vertexBuffer);

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

// Create a GPUBuffer and write the draw values into it
const drawValues = device.createBuffer({
  size: 16,
  usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.INDIRECT,
});
device.queue.writeBuffer(drawValues, 0, uint32, 0, uint32.length);

// Draw the vertices
passEncoder.drawIndirect(drawValues, 0);

// End the render pass
passEncoder.end();

// End frame by passing array of GPUCommandBuffers to command queue for execution
device.queue.submit([commandEncoder.finish()]);

// ...

Specifications

Specification
WebGPU
# dom-gpurendercommandsmixin-drawindirect

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
drawIndirect
113Currently supported on ChromeOS, macOS, and Windows only.
113Currently supported on ChromeOS, macOS, and Windows only.
previewCurrently supported on Linux and Windows only.
 No
99Currently supported on ChromeOS, macOS, and Windows only.
 No No No No No No No

See also

© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/GPURenderPassEncoder/drawIndirect