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Re: [Public WebGL] ARB_robustness and array bounds checking



On Mon, Oct 24, 2011 at 1:14 PM, Gregg Tavares (wrk) <gman@google.com> wrote:
> Not to be snarky but seriously? How many driver bugs have we found? And we
> want trust that some untestable feature is actually working?ÂIf it's not
> testable then it's not tested.ÂIf it's not tested it's not working.
> It would also be nice if the behavior was consistent because if drivers
> handle this differently (some return a specific value, others return the
> ends of arrays, others return a different value) you can be sure that people
> will ship apps, see that it works on their own hardware and then only later
> find that it's draw crazy stuff on other hardware.

Yep, this was the issue -- from what I remember, all the vendors
agreed that out-of-bounds access wouldn't read arbitrary memory, but
there wasn't consensus on whether it returned a constant value, the
end/beginning of array value, etc.  We pointed out back then that that
wasn't sufficient for the consistency reasons that Gregg points out.
Having a query as to what value is returned seems like a useful thing
-- then if the driver will happen to do whatever the WebGL spec
specifies, then we can skip the bounds checks (and the webgl spec
remains testable).

    - Vlad

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