Overgrowth takes place in the savage world of Lugaru where rabbits, wolves and other animals are forced to use paws, claws and medieval weaponry to engage each other in battle. Combining 3rd person adventure platforming with intricate melee combat, Overgrowth achieves a unique feel. Overgrowth also benefits from Wolfire's brand new Phoenix Engine which has been built from the ground up to allow the use of cutting edge graphics, animation, and physics. Add to these exciting features Overgrowth’s realistic artificial intelligence and streamlined control system and the result is an astoundingly immersive experience.

Report article RSS Feed Blending land and sky

Since Overgrowth mostly takes place outdoors, we put a lot of effort into making the sky look nice. We've already talked about the sun placement tools and atmospheric haze, but now I would like to talk about how we achieve smooth transitions between the land and the sky.

Posted by jeffr on Jul 22nd, 2009

Since Overgrowth mostly takes place outdoors, we put a lot of effort into making the sky look nice. We've already talked about the sun placement tools and atmospheric haze, but now I would like to talk about how we achieve smooth transitions between the land and the sky. Let's start at the beginning, with the panoramic sky texture:

Cloud sunset sky

Here is how that looks when we wrap it around a scene:

Partial sky

As you can see, the bottom half of the sky looks stretched and unrealistic. It doesn't match the terrain at all, so the edge of the terrain is clearly visible. To make it blend in better, we stretch out the terrain texture onto a large, slightly-indented plane that reaches to the horizon:

Partial sky

Now the scene look more complete. However, the horizon still has a harsh line between the land and the sky. To cover this, we use what I call a 'horizon band' or 'fog band', a fuzzy strip that is colored by a heavily blurred version of the sky texture. Here is what that looks like by itself.

Partial sky

When we put it all together, it all fits together pretty well, and the process is entirely automated in a fraction of a second! Here is the final result again:

Finished sky

Here are some other skies using the same technique, to show that it works for a variety of sky types:

Finished sky

Finished sky

This technique allows us to render convincing vistas very efficiently -- in terms of both development time and run-time resources. Do you have any ideas about how we could make the land and sky fit together even better? (permalink)


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formerlyknownasMrCP
formerlyknownasMrCP Jul 22 2009, 10:49pm says:

That's pretty impressive with how you got the lighting to match it almost perfectly. (the afternoon one looks a little bit under-exposed on the 3D part).

The best thing you could do for the game is try to have your own distant terrain rather than rely on a picture to create it for you- that way the user doesn't see distant terrain as a flat image (because these are easily noticeable- Racing games for example).

I can also see where this could be a problem if day/night as dynamic (if the sun goes behind one of the distant mountains which are 2D and on the image, the sun will in fact overlap them. This is fine for the clouds though.. but not for a solid object)

The day time one looks perfect though.

+2 votes     reply to comment
dill1233
dill1233 Jul 22 2009, 11:57pm says:

I love the concept you used in implementing this rendering effect. It really meshes the skybox and the terrain together as though it fades into the distance. Yet, I agree with Mr_Cyberpunk that the afternoon skybox feels a little under-exposed 3D-wise, but I think that creating distant terrain would take away too much power from low-end computers. I advise, though, adding a little bit more fog, or just messing around with shaders until you find the right one. Otherwise, this is a great addition to this game, and your team needs to keep it up.

+1 vote     reply to comment
Kai-Li
Kai-Li Jul 23 2009, 1:31am says:

Does it also work with a water environment?

+1 vote     reply to comment
jeffr
jeffr Jul 23 2009, 4:21am replied:

Not yet :) We are not sure if we will end up with water.

0 votes     reply to comment
Raph74
Raph74 Jul 23 2009, 10:50am replied:

Hi , i think you should implement water , because there are animals,so it should have water for them in the world .

+1 vote     reply to comment
Dra6o0n
Dra6o0n Jul 23 2009, 4:34pm replied:

Water element means more work (like combat in water would cause many splashes, thus more calculations), but you could keep them simple.

Water could also have a fun effect, like animals have the ability to jump or run on water (like ninjas o.O)

+2 votes     reply to comment
Eagle0600
Eagle0600 Sep 10 2009, 10:17am replied:

There's always the stopgap solution of just giving people super drowning skills.

+1 vote     reply to comment
-Kwah-
-Kwah- Jul 23 2009, 11:25am says:

Fffffuuuuuu-

If it's the polish that counts (Which at least in part, it is), you guys've got this set.

+1 vote     reply to comment
PierreOfTheFrench
PierreOfTheFrench Jul 23 2009, 2:29pm says:

You guys are amazing, at life, I can't wait to see this game. At this point I'm going to buy because of the scenery. I've been following all your updates and the whole engine looks fantastic, I'm not even worried about game play at this point :)

+1 vote     reply to comment
PierreOfTheFrench
PierreOfTheFrench Jul 23 2009, 2:41pm says:

Wait, I just read that if you preorder you get the game as is right now with it constantly being updated and released until the full game is out. Does that mean we gain access to the sunlight editor and things like this??? If so, I'm getting it now XD

Also, I see there are no system requirements available now but I was wondering if it requires pixel shader 3.0 or not? I have two computers ones really nice but I don't always have access to it. Just curious

+1 vote     reply to comment
PierreOfTheFrench
PierreOfTheFrench Jul 23 2009, 3:03pm replied:

Never mind, I just preordered it :)
They said probably 2.0 if anyone is wondering, and yes you do get access to weekly updated alphas

+1 vote     reply to comment
jeffr
jeffr Jul 23 2009, 3:42pm replied:

Thanks for the support!!

+1 vote     reply to comment
FW:ToW_Sushi
FW:ToW_Sushi Jul 24 2009, 9:49am says:

What's being done here is surreal. Great job, guys!

+1 vote     reply to comment
doublethink
doublethink Jul 26 2009, 3:30am says:

Really nice effect there.

+1 vote     reply to comment
Raden
Raden Jul 28 2009, 3:22am says:

Blah! I just love you guys. =) Great work as always.

+1 vote     reply to comment
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