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Re: [Public WebGL] Shader validation and limitations



Worse still, there is nothing the driver can do (even in principle) to
detect large quads because you can write vertex shader code that takes a
tiny quad and turns it into a gigantic one.  You can't reasonably chop
up 300 to 1000 triangle batches without totally crippling performance -
so (as I have maintained before) nothing short of a watchdog timer reset
will fix this.

We probably need to talk with the underlying driver authors (nVidia,
ATI, etc) about getting a watchdog timer feature into their code as an
OpenGL extension.  Since WebGL is very much in their interests (getting
3D graphics into more places and therefore selling more hardware) - they
ought to be cooperative.

  -- Steve.


Gregg Tavares wrote:
> Here's one more
> https://cvs.khronos.org/svn/repos/registry/trunk/public/webgl/sdk/tests/extra/slow-shader-example.html
>
> It's a 1 line shader, no loops. It draws just 1000 1024x1024 quads. It
> resets my Windows7 and had it both freeze my Macbook for 10-20 seconds
> on a couple of runs and also crash my Macbook completely on other runs.
>
> I can lower it to 300 polys and Windows7 will still reset and OSX will
> still freeze for 5-10 seconds. I didn't try other values since it's no
> fun to recover.
>
>

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