Difference between Linux and Windows ?


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Profile ChameleonScales
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Message 14752 - Posted: 3 Oct 2016, 21:11:47 UTC
Last modified: 3 Oct 2016, 21:15:41 UTC

Earlier Janus told me that BURP is separated in 3 farms : Linux CPU, Windows CPU and GPU, and that Linux and Windows are separated because the render results can have slight differences. I personally haven't had any different results from one another, and I'm curious to see what tests led to this decision.

Also I wonder if it would be possible that since those tests, the development of Blender would have unified the rendering process between Windows and Linux, which would allow BURP to merge the farms back.
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Message 14755 - Posted: 5 Oct 2016, 17:11:12 UTC

Only rarely does the issue seem to be with Blender itself (and we usually get those issues fixed by the folks at Blender.org pretty quickly when we report them). The underlying issue is connected with how the different platforms handle acceleration of 64-bit and 32-bit mathematical calculations. All the different results are correct as such, it is just that there is a little bit of wiggle room in the standards, especially for floating point calculations, as to how to carry out and optimize complicated math. In particular, rounding to the nearest available 64-bit floating point number and the order in which calculations take place is very important.

Not all sessions are affected by this issue, since it happens more often in complicated scenes with lots of raycasting and reflections going on.

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Message 14757 - Posted: 5 Oct 2016, 20:52:53 UTC - in response to Message 14755.
Last modified: 5 Oct 2016, 20:53:18 UTC

Thanks for the explanation. So I guess there's no much hope since the difference comes from the operating systems.
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Message boards : Client : Difference between Linux and Windows ?