Author Topic: Seed and random seed limitation to 256 ?  (Read 2194 times)

Offline Matt

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Re: Seed and random seed limitation to 256 ?
« Reply #15 on: December 15, 2013, 01:00:24 AM »
The Power Fractal Shader only has 256 unique seeds. After that the seeds repeat. I wasn't aware of that limitation when I made the Random Seed button generate values between 0 and 65535. The Alpine Fractal Shader and Fake Stones Shader have this limitation too, and probably other shaders that use noise functions. But other nodes in Terragen might have a larger number of seeds.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

Offline kaedorg

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Re: Seed and random seed limitation to 256 ?
« Reply #16 on: December 16, 2013, 09:52:25 AM »
Thanks Matt for this confirmation.

David

Offline D.A. Bentley

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Re: Seed and random seed limitation to 256 ?
« Reply #17 on: March 05, 2019, 02:25:14 AM »
The Power Fractal Shader only has 256 unique seeds. After that the seeds repeat. I wasn't aware of that limitation when I made the Random Seed button generate values between 0 and 65535. The Alpine Fractal Shader and Fake Stones Shader have this limitation too, and probably other shaders that use noise functions. But other nodes in Terragen might have a larger number of seeds.

Matt

I verified today that Easy Cloud doesn't have the 256 seed limitation.  Maybe because that was new in TG4 it got the full 65535+?  It would take a long time to render 1 - 65536 so I didn't do that, but I did render frames -256 to 512 and saw no repeats.  Then I rendered some frames in the range 65530 - 65540 and couldn't exactly match any of those up to the frames down close to the "zero seed".

So I have no idea how many variations there are but I suspect it is in the millions or more.  Any ideas Matt?

Now I'm curious about Cloud layer v3.  :)

-Derek

Offline Matt

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Re: Seed and random seed limitation to 256 ?
« Reply #18 on: March 05, 2019, 03:16:28 AM »
The Easy Cloud contains 3 built-in fractals (at the moment). All of the built-in fractals are limited to 256 seeds each (because they suffer from the same limitation as the Power Fractal). However, I added some extra randomness by calculating a random seed for just one of the built-in fractals based on the 32-bit input seed. This makes it harder to find duplicates, but they still occur quite often. Theoretically there are now 65536 combinations, but the duplicates will exist in somewhat random places, so you'd need to try a much larger set of seeds if you wanted to find them all.
Just because milk is white doesn't mean that clouds are made of milk.

Offline D.A. Bentley

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Re: Seed and random seed limitation to 256 ?
« Reply #19 on: March 05, 2019, 03:37:30 AM »
Oh ok, I was rendering the Cumulus TG 3.9.07 Type.  That must be the one with more randomness right?

-Derek

Offline Matt

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Re: Seed and random seed limitation to 256 ?
« Reply #20 on: March 05, 2019, 04:07:14 AM »
I'm not sure but I think they all do (in Easy Cloud).
Just because milk is white doesn't mean that clouds are made of milk.

Offline D.A. Bentley

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Re: Seed and random seed limitation to 256 ?
« Reply #21 on: March 05, 2019, 07:42:56 AM »
I'm not sure but I think they all do (in Easy Cloud).

Ok I understand.  I misunderstood what you were saying about three different fractals, and how one of them was full 32-bit and blended with the other two.  For some reason my brain interpreted that as referring to the three different types of clouds within Easy Cloud (Al, Cu, St), but after re-reading it and doing some rendering I get it now.  The attached picture shows how the "Roll Around" seeds look similar in some cases, but still have unique parts.  In that image the third column is just a blending of the two seeds being compared from column 1 & 2.

I only rendered 30 with what I thought would be duplicate "Roll Around" seeds, but of those I could only see in 7 of the clouds some similarities, and even then it was hard to spot without careful examination.  This is very good for rendering random cloud sprites!!!

Thanks Matt!

-Derek
« Last Edit: March 05, 2019, 07:46:55 AM by D.A. Bentley »

Offline Matt

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Re: Seed and random seed limitation to 256 ?
« Reply #22 on: March 06, 2019, 01:59:43 AM »
Thanks. I do what I can :)
Just because milk is white doesn't mean that clouds are made of milk.