### (Question) iterational/dynamic fog

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#### Sabine62

• Fractal Freak
• Posts: 667

#### iterational/dynamic fog

« 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...

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

To thine own self be true

• 3f
• Posts: 1548

#### Re: iterational/dynamic fog

« 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 »

• 3f
• Posts: 1548

#### Re: iterational/dynamic fog

« 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

#### Sabine62

• Fractal Freak
• Posts: 667

#### Re: iterational/dynamic fog

« 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 , but only just was able to finally answer your message and it's late over here.

• 3f
• Posts: 1548

#### Re: iterational/dynamic fog

« 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

#### mclarekin

• Fractal Freak
• Posts: 660

#### Re: iterational/dynamic fog

« 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.

• 3f
• Posts: 1548

#### Re: iterational/dynamic fog

« 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

#### Sabine62

• Fractal Freak
• Posts: 667

#### Re: iterational/dynamic fog

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

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*...  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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