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Submitted by Tom Vykruta, posted on January 07, 2001

Image Description, by Tom Vykruta

Volumetric fog example. Screenshot comes from Traveler's Quest, a free, persistent MMORPG mod based on Drakan (Riot Engine). This isn't "true" volumetric fog, it's something I threw in last night, works great for our engine and is much cheaper than defining true fog volumes.

Tom Vykruta

Image of the Day Gallery


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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.

January 08, 2001, 02:49 PM

that looks great ... but ... can you explain how you do that fog ?


January 08, 2001, 02:54 PM

Looks nice! I thought those houses looked familiar (Drakhan :)

I'd also like to know how you fake the fog ... I'd really also like to see it moving, since that's really the point when fog starts to look very unrealistic.

BTW, why does your character only wear boots (and yellow skin)? :)

- MK42


January 08, 2001, 03:31 PM

You just gotta luv the RIOT engine. Drakan was a great game based on that engine. Fog looks really good. I remember Drakan's extensive use of fog in coordination with it's visibility determination because of the huge outdoor environments for the game.


January 08, 2001, 03:52 PM

I couldn't say it's something very special, but it looks nice.
Also that girl... I see that she is enjoying your fog as well as we.


January 08, 2001, 04:34 PM

This screenshots is great.. especially for a free mmorpg MOD. To buddy who said "it's nothing special" - you're a prick, every message you post is negative. (I'm not making this up - take a look for yourself

Daveed Koffler

The Wolf

January 08, 2001, 04:52 PM

very nice, I love the effect. Do you have another shot maybe closer to the fog?


January 08, 2001, 05:13 PM


Louis Howe

January 08, 2001, 05:20 PM

That image looks very, very professional! The fog definitely adds to what would still be an incredible-looking game. I too am a curious as to how it's done, and what sort of visibility algorithms are in use.

To Mr. Baxton: although I'm sure your comments are probably sincere and not meant in a destructive way, I see how they can be interpreted as offensive. Perhaps you should try adding positive suggestions if you see a way to make something better...


January 08, 2001, 05:45 PM

Every day or so a new IOTD is posted... and every day MC BAXTON has something to say which a group of you don't agree with. And every day some dink responds and starts up yet another small flame war.

Please, for the love of god, don't feed the trolls.

RE: the IOTD:
Nice image. I haven't seen fog very often which appears near water, or appears to come from somewhere.

Saad Faisal

January 08, 2001, 05:48 PM

Impressive and looks beautiful. Could u plz tell us that r u planning to provide a downloadable demo for this effect so that we call can see that on our cards.


January 08, 2001, 06:16 PM

Some answers...
Q. " see it moving, since that's really the point when fog starts to look very unrealistic"
A. It looks correct (as you would imagine it) when moving around / through it. Walking into the fog bank is especially captivating.

Q. Does the character wear clothes?
A. Sometimes. Other times she likes to take them off and touch herself.

Q. Will I release a demo?
A. The screenshot comes from a persistent mmorpg I am working on in my spare time.. we will be holding a beta test in the future. for more info.

Q. How did you do it?
A. I can't fully explain it as you would need to know the internals of the engine.. basically, there is an area-defined fog plane (in the screenshot example, imagine a plane covering the river). Because the plane is a constant world-relative-height and the fog is assumed to be a constant density and reaching all the way to the ground, the math behind it is quite cheap to calculate (nearly free). The volumetric fog is vertex based, not per-pixel, another huge optimization. The downfall is that it can look incorrect when applied to a very low-resolution landscape (vertices spaced far apart). The scene in the screenshot is only 2100 polys, so obviously it's not too big of a problem. From a designer's perspective, they choose the area to have the fog, define a fog height (the imaginary plane) and density, the engine handles the rest. What the system can't do is have a small pocket of fog hovering in mid air. This however is an unrealistic exploitation of vol. fog hence no big loss.

Tom Vykruta


January 08, 2001, 06:50 PM

" Q. Does the character wear clothes?
A. Sometimes. Other times she likes to take them off and touch herself. "

Ehmm... yes... You still need beta testers? ;)


January 08, 2001, 06:58 PM

We arent doing large scale beta testing yet but if any of you are artists of any type...drop Tom or I am email.


January 08, 2001, 07:09 PM

I use a very similar, (possibly Identical) method for doing Mist-type fog in my own 3D Engine. I thought I was the only one doing it that way, but Im glad to see more people have thought of it. THe screenshot is very nice. Keep up the good work!



January 08, 2001, 07:25 PM

very nice shot! i like the ambient and the trees are nice!
how are you doing your trees there? :) 3d model?


January 08, 2001, 07:42 PM

Sorry, I have something negative again ...

To tell the truth, your fog looked for me suspicious from first look.
The tree behind bridge is visible almost(I'd say absolutely) without fog. However, the distance from viewer to river and from viewer to tree is very similar. But fog exists only on the river.
If fog gets more dense near the ground, in this case the same effect should be everywhere. But we can notice "vertical" fog over the hills and "horizontal" over the river. Usually you NEVER experience those two kinds of fog mixed at the same time in nature.

However, it's still possible to fool quick eye with those tricks.


January 08, 2001, 07:43 PM

maybe its just me, but i was under the strange impression that the riot engine already supported plane/box defined vertex volume fog and was used when looking into water.

Regardless, this shot is brilliant. Myself, i'd make the fog a little more transparent for this scene but its your project and it looks damn good!


January 08, 2001, 08:00 PM

Very nice screen shot, from a very cool game.

Baxton, do you even know how to program? I am just wondering, because with all of these wonderful comments you make, I would certainly expect you to be the next Carmack or Meijer. Your ramblings remind me of those gurgitated from fevered children and cenile old men. If you are one of the former, I apologize, if not, why don't you go somewhere else. I would hate to think this forum is keeping you from spreading your negativity and ignorance to others that may appreciate them more. BTW, realism is sometimes not the desired effect. When I play games, I don't want realism, I'll watch CNN for that. What I want is an experience that is pleasing to my senses. I don't want the programmer spending hundreds of hours trying to make my experience real. Real is what I am escaping from. Anyway, go away.


January 08, 2001, 08:14 PM

you don't live near a forest, do you?
while you are partially correct, the fog would actually "attach" itself to the tree and become discombobulated from the rest of the scene (moisture gathers at moisture rich areas).

For what he has done, though, it looks brilliant, especially if it renders quickly!


January 08, 2001, 09:14 PM

Re MC BAXTON's message:
I must disagree. That sort of fog is common on mornings over lakes, and I'm sure, to a smaller degree, over rivers. However, I would say that the fog over the river is a bit thick... Maybe it would look better if it weren't quite as 'bright', (about 200,200,200 rgb instead of fullbright?) Anyway, I haven't heard of this engine before (no, I don't buy many games. I do, however, claim to program)
I'd like to see some more info on it.
All in all, an excellent pic though.

thanks -

(heard of draken, not the name of the engine though - RIOT)


January 08, 2001, 09:36 PM

But this fog just too different in places which are near each other.


January 08, 2001, 09:39 PM

I think people need to lay off MC BAXTON. He is a great guy, I personally think that we should all comment on things as if we know it all, and nothing is as good as anything we do. It creates a really happy forum, and really makes people want to share their creative talent.

Lets see an example of your work BAXTON, so we can "critique" it as you have others.

Daveed Koffler


January 08, 2001, 10:05 PM

If fog over the river would be "a bit" higher and less dense it would be better, but now it still looks unnatural. Fog can be varied in density, over the lakes. Over small rivers, like shown, changes in density should be less noticeable. So, it's not correct and it's noticeable


January 08, 2001, 10:39 PM



January 08, 2001, 10:43 PM

Working at a video game company and making free games on the side?

Something about that just seems kind of crazy!

"Welcome to starbucks! Would you like a frappacino for $4.95 or maybe some of this fresh brewed coffee I brought from home for free?"

fog looks good - and mc baxton, maybe if you ask nice the developers can give you a special 1fps version with no distance fog.


January 08, 2001, 11:02 PM

Um...the fog can be has parameters. The shot is just an off the cuff screenshot of a testcase made by Tom for sake of testing his "first pass" code. Didnt you notice the yellow naked player character? The notion that someone would have so much to say about the details is stupid.

In the end...any tweaking will be made to look cool within the idea of fantasy environments. That is the point afterall.


January 08, 2001, 11:16 PM

Very cool image. Although it doesn't look that different from Drakkan, except Rynn wore clothes :-). I am new to 3D graphics and I don't really understand your description of how the fog works. I'm gonna research it though.


January 08, 2001, 11:28 PM

bgl's message has been deleted by Moderator 2.
Reason: Insulting comment, contributes nothing to the thread.

Scrambled Monkey

January 09, 2001, 01:37 AM

I think it looks rad! A lot better than most vfog stuff I've seen. By the way, it's good to see Banana Man's wife finally has a franchise of her own... :)


January 09, 2001, 03:35 AM

Huh? Well, this comment was related to the topic and it wasn't insulting. What's the point in deleting a message that says "it looks at least halfway decent" ?
I suggest Kurt should nominate some moderators with at least a spark sense of humor.

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