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Re: [Public WebGL] about the VENDOR, RENDERER, and VERSION strings



----- Original Message -----
> What will leak roughly
> 10 bits of information? How do you come up with this value?

See earlier discussion with Cedric: for NVIDIDA desktop/laptop video cards alone, there are at least 200 devices, counting only OpenGL 2 devices that can be used for WebGL. I know this from handling graphics driver crashes in Mozilla, I assembled as complete a list as I could for NVIDIA:

https://bug605749.bugzilla.mozilla.org/attachment.cgi?id=484688

that's where I get my number 200 from, and I know that this list is still very incomplete. There are many ATI cards too, here's a list with 120+ cards, again I know it's very incomplete:

http://developer.amd.com/drivers/pc_vendor_id/Pages/default.aspx

For Intel there are roughly 25 relevant card types (there are more PCI IDs but many duplicates).

So the total number of RENDERER values is of the order of magnitude of 2^9, so RENDERER alone gives 9 bits of info on platforms where any graphics card is possible (Windows and Linux desktops and laptops).

Now if you add the VERSION string, which contains the precise driver version, you get a few more bits, say roughly 4 bits in my experience (many people can never upgrade their OEM drivers), so the total is like 13 bits, so my 10 bits estimate was very conservative.

Cheers,
Benoit

> 
> I suspect that the range of discreet values returned by the MAX
> queries is actually quite small across implementations. For example I
> expect MAX_VIEWPORT_DIMENSION will be one of 1024, 2048 or 4096.
> across the many, many different models of graphics cards. Therefore
> the amount of information leaked will not be so great.
> 
> Regards
> 
> -Mark
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