Re: [Public WebGL] WebKit 20-50% slower than Chrome/Minefield using large Float32Array Arrays

[Kenneth Russell <kbr@google.com>]

On Thu, Feb 17, 2011 at 4:16 PM, Stephen Bannasch
<stephen.bannasch@deanbrook.org> wrote:
>
> At 11:23 AM +0100 2/17/11, Thatcher Ulrich wrote:
>>Cool demo.
>>
>>One thing you should try, without even going to WebGL, is filling the
>>canvas using context.putImageData() instead of lots of fillRect calls.
>> Perhaps also best to render into a 100x100 canvas, and have the
>>browser scale it onto the correct size on the page, instead of doing
>>that in your paint routine.
>
> Thatcher,
>
> Thanks for the suggestion, it works much better. I implemented it and the canvas renderings is about 50% faster.
>
> https://github.com/stepheneb/seasons/blob/master/earth/model2d.js#L1960
>
>>The other thing you should definitely do is make a color table instead
>>of making and parsing "hsl(...)" strings for every pixel.
>
> The div-stuffing method is now slower than the canvas rendering but it wasn't that slow.
>
> The div-stuffing method pre-generates 256 css rules, inserts them into the stylesheet and 256 div strings and puts these into an array.  Later when generating the string to insert with innerHTML I build it out of the pre-computed array of div strings that reference each of the 256 styles.
>
> But ... there's a new mystery! A colleague asked how much slower it would be if I didn't use typed arrays ... so now there are two alternate implementations that link to each other:
>
>  http://visual-demos.dev.concord.org/seasons/earth/model2d.html
>  http://visual-demos.dev.concord.org/seasons/earth/model2d-reg-arrays.html
>
> On my Chrome version 9 using regular arrays and rendering runs about 7.1 fps while using typed arrays is slower at only 5.4fps.
>
> On plain old Safari v5 I'm getting 3.6 fps.
>
> Without rendering Chrome 9 runs about 41 fps using regular arrays and only about 31 fps with the Typed Arrays. Minefield isreversed running about 41 fps using Typed and 28 fps using regular arrays.
>
> Regular Safari runs about 21 fps without rendering.
>
> http://visual-demos.dev.concord.org/seasons/earth/model2d-reg-arrays.html
>
> I have made a few other changes in the model but none that I thought would slow doiwn typed-arrays.

Just FYI, further optimizations are planned for typed arrays in V8.
Currently certain optimizations are done for normal JavaScript arrays
that aren't in place for typed arrays.

-Ken

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