Support for indirect draw calls for WebGPU

[mvaligursky]

Implementation of indirect draw calls on WebGPU )both indexed and non indexed). The implementation uses a single storage buffer to store draw call parameters, allowing their batching into a small number of compute shaders to get the best performance, based on this.

Live example: https://engine-fwazdfd1j-playcanvas.vercel.app/#/compute/indirect-draw

Public API:

// storage buffer which stores the draw call parameters
GraphicsDevice.indirectDrawBuffer() 

// function to allocate a slot in this buffer
GraphicsDevice.getIndirectDrawSlot()

// read - write property controlling the size of that buffer (number of indirect draw calls)
GraphicsDevice.maxIndirectDrawCount = 1024;

// enabled MeshInstance rendering by indirect parameters from a slot
// for a camera. Camera can be null to use for all cameras
MeshInstance.setIndirect(camera|null, slot)

Graphics Device docs:

Mesh Instance docs:

example:

[LeXXik]

Nice! Couple of questions:

• Does this work in Safari?
• Will WEBGL_multi_draw new extension, potential huge CPU-GPU overhead optimisation. #1498 work with it? Nevermind, thats WebGPU only.

[mvaligursky]

| Does this work in Safari?

It works in my local WebKit browser using WebGPU, so I suspect when Safari with WebGPU is officially out, it will just work.

[willeastcott]

It might be a good idea to add one or more @example blocks to the JSDocs showing how to use the new API.

[willeastcott]

I know there are other places in the scene layer that import from the framework layers...but here's a new one!

[mvaligursky]

Yep, I'm stuck with it here. Camera is not public so I cannot use that, and don't see a good way around it.

[mvaligursky]

addressed all other comments, thanks!

[willeastcott]

Approving assuming you're gonna add some example code or link to the example as an alternative.

[mvaligursky]

Approving assuming you're gonna add some example code or link to the example as an alternative.

added this:

[mvaligursky]

updated