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Re: [Public WebGL] ANGLE_instanced_arrays extension proposal





----- Original Message -----
> 
> 
> 
> ----- Original Message -----
> > On Tue, Mar 6, 2012 at 4:01 PM, Florian BÃsch <pyalot@gmail.com>
> > wrote:
> > > On Wed, Mar 7, 2012 at 12:57 AM, John Bauman
> > > <jbauman@chromium.org>
> > > wrote:
> > >>
> > >> If you want you could do that only on the first instanced draw
> > >> from a
> > >> buffer, and keep a shadow copy afterwards, but it might be
> > >> difficult to make
> > >> that perform well.
> > >
> > > No nead for readbacks, if you intercept bufferData calls and
> > > create
> > > a shadow
> > > copy then which you manage, you can do the right thing once
> > > before
> > > draw.
> > 
> > This implies that the WebGL implementation maintains a copy of all
> > vertex data that's been uploaded. As I mentioned above I think this
> > is
> > impractical on mobile devices.
> 
> Not just on mobile devices, but on desktop too, given that our
> desktop users care about memory usage too.

Except that I am stupid: desktop support instanced_arrays already, so we wouldn't need to do this on desktop. Sorry.
Benoit


> 
> In Firefox, you can see how much (video) memory WebGLBuffers use by
> going to about:memory, and scrolling down to webgl-buffer-memory.
> It's often large enough that we'd need a very good reason to keep a
> copy of it on the heap. For example, this simple Quake3 level
> renderer,
>     http://media.tojicode.com/q3bsp/
> uses 1.66 MB of buffer data, and that's just an idle empty level.
> 
> Opera's Odin demo,
>     http://operasoftware.github.com/Odin/demo.html
> uses 2.05 MB of buffer data, with just one animated character and
> some objects around it.
> 
> Benoit
> 
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