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I've been playing with webGL particles and I'm surprised that texture upload is chosen over normal attribute arrays. I'll have to try it out and see if its faster.

I've found it best to not update anything if you can help it, so use procedurally generated particle effects.

For example, to follow the mouse, I'd be passing in a smoothed curve the mouse has recently travelled down as uniforms. This doesn't work the same way, and won't give as exact results, but does look nice.

One of my blog posts, related: http://williamedwardscoder.tumblr.com/post/43800948133/effic...

More recently I've been doing effects using Perlin Noise at an extra dimension - time - and that works great for stuff like plasma effects that don't have to react with the environment. http://williamedwardscoder.tumblr.com/post/57181055984/perli...

Texture upload is a great choice because it means your particle update routine can be a pixel shader that you run the current 'state' texture through to produce a new 'state' texture. Then you're literally running the whole thing on-GPU. Not aware of ways to do that at present with DX9-class hardware or with the WebGL feature set. Modern desktop GL and DirectX let you write to and read from basically anything, as I understand it.
> Texture upload is a great choice because it means your particle update routine can be a pixel shader that you run the current 'state' texture through to produce a new 'state' texture.

Yep. This is how GPGPU programs were done some 10 years ago when there was no API to deal with GPU buffers in a more flexible way.

These days we've got Transform Feedback (aka. Stream Out in D3D) and Compute Shaders that are more flexible. And Cuda and OpenCL, of course.

One thing you should be aware of when doing this kind of texture-to-texture GPGPU is that the internal GPU pipeline in GLES2 (and thus, WebGL) may be less than full 32 bit floating point. Also the texture formats being used are not full floats. So watch out for numerical precision issues!

I actually cant manage to get this page to work for me. Could it possibly be something to do with the fact im running Linux? Does chrome for linux support WebGL yet?
>Could it possibly be something to do with the fact im running Linux?

No.

>Does chrome for linux support WebGL yet?

Yes.

I can run this on Linux with Firefox and Chromium.

Check that you have OpenGL properly set up (e.g. correct gpu drivers).

In addition use the WebGL extension check to see that your OpenGL version (ie. GPU and drivers) can access textures from the vertex shader. It's a feature that was added a few years ago, there may still be hardware/software versions that doesn't allow this.

This demo certainly uses texture sampling from the vertex shader. It's a feature that enables a lot of fun effects, but is not required by the spec. Check this page to see if your MAX_VERTEX_TEXTURE_IMAGE_UNITS is > 0 http://renderingpipeline.com/webgl-extension-viewer/
Chrome is over-agressive in blacklisting GPU drivers on Linux, try Firefox.