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From: scott
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 29 Jul 2015 04:19:24
Message: <55b88c8c@news.povray.org>
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So do you remember a few years(?) back when 3D Mandelbulbs were all the
rage? IIRC there were some threads on these very groups about rendering
them in POV, however it was painfully slow.
Well now you can do it in realtime on a (fast) GPU near you :-)
I need to tidy up the code a bit to make it easier to "fly around" and
control the detail settings, but here's a quick teaser:
https://www.youtube.com/watch?v=r_Ek3Kfv8KA
Note there's nothing pre-calculated here, the GPU is doing all the work
on the fly.
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From: clipka
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 31 Jul 2015 20:55:52
Message: <55bc1918$1@news.povray.org>
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Am 27.07.2015 um 19:35 schrieb Orchid Win7 v1:
> I wonder how long before GPU gets a hardware-based randomness source?
> (It can't be that hard to sample a little thermal noise in hardware,
Well, GPUs should at least be able to provide plenty thermal for the
noise ;)
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From: scott
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 4 Aug 2015 04:55:14
Message: <55c07df2$1@news.povray.org>
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>> I wonder how long before GPU gets a hardware-based randomness source?
>> (It can't be that hard to sample a little thermal noise in hardware,
>
> Well, GPUs should at least be able to provide plenty thermal for the
> noise ;)
Yes :-) It's not hard to sample the thermal noise, the problem is how
to sample it billions of times per second with enough resolution to be
useful.
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From: Orchid Win7 v1
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 4 Aug 2015 13:00:38
Message: <55c0efb6@news.povray.org>
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On 04/08/2015 09:55 AM, scott wrote:
>>> I wonder how long before GPU gets a hardware-based randomness source?
>>> (It can't be that hard to sample a little thermal noise in hardware,
>>
>> Well, GPUs should at least be able to provide plenty thermal for the
>> noise ;)
>
> Yes :-) It's not hard to sample the thermal noise, the problem is how to
> sample it billions of times per second with enough resolution to be useful.
Well, no, you typically sample it a few times a second and use that to
seed a normal PRNG.
In other news, Intel added an op-code to generate truly-random numbers
using exactly this technique. The Linux kernel team added it to
/dev/random... and then took it out again, because they were apparently
concerned that the NSA would modify the die of your CPU to make the
random numbers non-random. (!!)
Jesus, that's next-level. Surely if you don't trust the hardware your OS
is running on, it's already game over. (?)
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From: scott
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 5 Aug 2015 04:24:23
Message: <55c1c837$1@news.povray.org>
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>> Yes :-) It's not hard to sample the thermal noise, the problem is how to
>> sample it billions of times per second with enough resolution to be
>> useful.
>
> Well, no, you typically sample it a few times a second and use that to
> seed a normal PRNG.
But will that not cause the same problems seen already today with
unrandomness? If the pixel shader for every pixel gets exactly the same
random seed value, and just uses a PRNG to modify it, won't you see
patterns? I would have thought every pixel needs its own unique random
seed value every frame to really get rid of those sort of PRNG patterns.
If you want a *truly* unbiased ray tracer for example.
> In other news, Intel added an op-code to generate truly-random numbers
> using exactly this technique. The Linux kernel team added it to
> /dev/random... and then took it out again, because they were apparently
> concerned that the NSA would modify the die of your CPU to make the
> random numbers non-random. (!!)
Apparently the on-chip thermal noise sampler outputs a stream of bits at
3 GHz. I don't know how big the hardware is for that circuit, but it's
not *that* far away from what you'd need to get a true random number for
every pixel processed on the GPU.
> Jesus, that's next-level. Surely if you don't trust the hardware your OS
> is running on, it's already game over. (?)
Yes, something like a true RNG in every home home PC seems like
something the NSA would be extremely interested in.
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From: Orchid Win7 v1
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 5 Aug 2015 16:28:40
Message: <55c271f8$1@news.povray.org>
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On 05/08/2015 09:24 AM, scott wrote:
>>> Yes :-) It's not hard to sample the thermal noise, the problem is how to
>>> sample it billions of times per second with enough resolution to be
>>> useful.
>>
>> Well, no, you typically sample it a few times a second and use that to
>> seed a normal PRNG.
>
> But will that not cause the same problems seen already today with
> unrandomness? If the pixel shader for every pixel gets exactly the same
> random seed value, and just uses a PRNG to modify it, won't you see
> patterns?
My plan was more to have some hardware that seeds a PRNG with a
truly-random seed and then distributes a *different* random iterate from
the PRNG to each thread in the bunch. It's awkward to code in software,
but shouldn't be that hard in hardware...
> Apparently the on-chip thermal noise sampler outputs a stream of bits at
> 3 GHz. I don't know how big the hardware is for that circuit, but it's
> not *that* far away from what you'd need to get a true random number for
> every pixel processed on the GPU.
OK.
>> Jesus, that's next-level. Surely if you don't trust the hardware your OS
>> is running on, it's already game over. (?)
>
> Yes, something like a true RNG in every home home PC seems like
> something the NSA would be extremely interested in.
It's slightly mental that the government of one country can insert spy
hardware into every computer that can ever exist... Especially given
that all silicon fabrication is done in countries hostile to America...
But hey, what do I know?
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From: scott
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 6 Aug 2015 03:20:12
Message: <55c30aac$1@news.povray.org>
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> It's slightly mental that the government of one country can insert spy
> hardware into every computer that can ever exist... Especially given
> that all silicon fabrication is done in countries hostile to America...
> But hey, what do I know?
Oh don't worry, I'm sure if the NSA were capable of inserting spy
hardware into CPU dies, the fab itself would be more than capable of
changing it back to something more to their (or their government's)
liking :-)
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scott <sco### [at] scottcom> wrote:
> > I got a "Could not initialize WebGL" message. with a quadro FX3800
>
> Does WebGL work at all on other sites? Try these:
>
> https://www.chromeexperiments.com/webgl
> https://www.shadertoy.com/
no. it doesn't. too bad.
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From: clipka
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 6 Aug 2015 06:34:33
Message: <55c33839$1@news.povray.org>
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Am 06.08.2015 um 09:20 schrieb scott:
>> It's slightly mental that the government of one country can insert spy
>> hardware into every computer that can ever exist... Especially given
>> that all silicon fabrication is done in countries hostile to America...
>> But hey, what do I know?
>
> Oh don't worry, I'm sure if the NSA were capable of inserting spy
> hardware into CPU dies, the fab itself would be more than capable of
> changing it back to something more to their (or their government's)
> liking :-)
That's what I was thinking. Yes, absolutely, totally. They'd sure know
exactly what features to look out for in a set of lithography masks...
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From: scott
Subject: Re: Friday afternoon project: a real time ray tracer in your browser
Date: 6 Aug 2015 06:56:23
Message: <55c33d57$1@news.povray.org>
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>> Oh don't worry, I'm sure if the NSA were capable of inserting spy
>> hardware into CPU dies, the fab itself would be more than capable of
>> changing it back to something more to their (or their government's)
>> liking :-)
>
> That's what I was thinking. Yes, absolutely, totally. They'd sure know
> exactly what features to look out for in a set of lithography masks...
Only if they were "run" by the government - then I'm sure a team of
100's to reverse engineer and "fix" the "problem" would be easily
available for the job...
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