(Question) iterational/dynamic fog

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Offline Sabine62

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« on: July 04, 2019, 02:13:44 PM »
Mandelbulb3D has a feature called dynamic fog and Mandelbulber probably has something alike called iterational fog.
I would like to have a look at if it's possible to implement it somehow in FragM. But as of now I have no understanding of how I could possibly influence the fog(s) we already have by iteration count, or if that is at all the way to go... :fp: ::)

Any info (for beginners!  ;) ) would be greatly appreciated!

Linkback: https://fractalforums.org/noobs-corner/76/iterationaldynamic-fog/2911/
To thine own self be true

Offline 3DickUlus

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« Reply #1 on: July 06, 2019, 05:13:21 AM »
I recall iteration fog  being demonstrated some where... will try to find it... or remember how  :-\

http://www.fractalforums.com/fragmentarium/iteration-fog/

it's already in the default Examples->Historical 3D Fractals->Mandelbulb.frag in the uniform tab "Light" Glow and Glow Max are the uniform names, you can find them in DE-Raytracer.frag around lines 384 and 393 (GlowMax line 342 ), it's setup to only show this "fog" for background and floor hits, just a minor tweak to make it show in the bulb/object crevices and hollows ;)
« Last Edit: July 06, 2019, 05:47:21 AM by 3DickUlus »
Fragmentarium is not a toy, it is a very versatile tool that can be used to make toys ;)

https://en.wikibooks.org/wiki/Fractals/fragmentarium

Offline 3DickUlus

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« Reply #2 on: July 06, 2019, 06:06:27 AM »
in DE-Raytracer.frag
lines 383 - 385
Code: [Select]
// if (floorHit ) {
hitColor +=Glow.xyz*stepFactor* Glow.w;//*(1.0-shadowStrength);
// }

line 393
Code: [Select]
hitColor +=Glow.xyz*stepFactor* Glow.w;//*(1.0-shadowStrength);

result with pure red Glow color... more iterations = more color

Offline Sabine62

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« Reply #3 on: July 09, 2019, 11:47:58 PM »
Thanks a lot for all the lookups and links and the example, Dick, but I'm afraid this is not what I meant. Neither is it in the threads you mention. Syntopia says his DE-Raytracer-glow is iteration dependant, but I cannot reproduce  :'( The volumetric fog in the DE-Kn2cr11.frag-thread is something different too.

Below some examples from MB3D with dynamic fog varying on iteration count...
As you can see there is some fog at iter=1, none at iter=7 and 84, and varying fog at the other iterations (though you cannot really see it at 98)

PS: Sorry for the horrible images :fp:, but only just was able to finally answer your message and it's late over here.

Offline 3DickUlus

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« Reply #4 on: July 10, 2019, 01:56:27 AM »
well, what I pointed out is "itertion fog", the fog in KN_VOLUMETRIC is iterated n times during each raymarch, so... not sure what you're getting at, "a picture is worth a thousand words" ;)

attached: KN_VOLUMETRIC HF_FogIter=3

Offline mclarekin

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« Reply #5 on: July 10, 2019, 01:23:35 PM »
@ sabine.   I have yet to learn about  fog , (but enhancements are planned), i am not yet ready to try and make sense of the existing code :)  Currently we have  basic fog, iter fog and fog based on distance.

Offline 3DickUlus

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« Reply #6 on: July 11, 2019, 01:20:45 AM »
This might be of interest...

"snapshot/quote" from https://www.khronos.org/registry/OpenGL-Refpages/gl2.1/xhtml/glFog.xml

Offline Sabine62

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« Reply #7 on: July 12, 2019, 02:48:27 PM »
Thanks again, Dick!  :thumbs: And sorry that I was not clearer from the start, should have posted some images right away  ;D

Graeme, I really wish Mandelbulber would  not try to explode my machine all the time so I could explore further than change one thing, hit render and *poof*...  ;D ;D ;D I have seen images by you that look quite a bit like what I am after:
 
Image by mclarekin: https://fractalforums.org/index.php?action=gallery;sa=view;id=2863

I will not have time until next week to have a closer look at things, got a bit swamped here by all sorts of things happening ::)


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