Awesome Trees

[petachok]

Hey guys,

Nice project you have going here. I'm just wondering how you manage to have such high-quality trees rendered in real time. There must be so many polygons generated there all at once. Is there some trick to this, or do you just have uber computers?

[Mythos_Ruler]

Alpha maps are our friends....

[petachok]

So are those 2D trees, or are you billboarding individual leaves, or groups of leaves? Or are you just using leaf textures with alpha maps over them without billboarding?

Edited February 7, 2006 by petachok

[Mythos_Ruler]

I'll let CheeZy (our resident gaia artist) answer all those questions. He's very proud of his work and always looking to improve things. He's very knowledgeable.

[Aeros]

He's very proud of his work and always looking to improve things.

I did maybe 4 drafts of trees over a year before we got to the model we use now, each time using less polygons and less texture.

I'll hold off on details right now because I'm probably going to be talking about this in the near future when you guys will get a major update on WFG and 0 A.D. but to answer your question here, the trees have 5-10 times less polygons than a typical unit and use about 24KB of texture memory per color/shade. We have a clever randomising system that assembles the trees and picks their color. When I say clever, I mean its just that, we make use of the same randomising system that assigns random facial features and weapons/shields to units. If we had the art assets in place this system could be used to randomise anything as many times as you want, one idea was to have randomised props and eyecandy around buildings so it looks different each time, but for now thats not a priority and I don't think we will be doing it unless we (artists) have spare time to do so.

The tree randomizations...Right now its not too dramatic, but that is due to the art assets, I want to go in for a 5th draft sometime and make the trees look even more random. Right now though, the variation and the branch detail combined with random rotation upon placement (and later on, random scaling) ensure you practically never see the same tree twice, aside from the fact that their assets look too similar right now for my liking .

So are those 2D trees, or are you billboarding individual leaves, or groups of leaves?

We design the trees by creating a branch that is 1 face (thats right 1 face a triangle, not 2 faces, a square) and then build the tree by aranging these branches in 3d space the way you would see them in a real tree. Due to the way the branch texture is designed this looks very convincing. The true beauty in the trees is revealed when you are rotating the camera. They look like sprite quality in screenshots but imagine them spinning around in 3d. Because of this branch method the trees look extremely dense and 3d and use only 20-35 face per canopy. (+30-60 for the trunk/base)

This is what happens when you get some artists to devote some time into their work rather than crunching them and making them turn out all the art for a game in a months time the way proffesional game developers work.

btw...2d trees?! do you think we'd cheap out on you like that?

Edited February 8, 2006 by CheeZy

[petachok]

Oh that sounds really cool.

So each branch uses only one face? Hmm that sounds interesting, but I don't seem to get how your trees still manage to look 3D. I was assuming you guys used Meshes to create the tree trunk+branches. Also seeing that you guys are able to modify the appearance of the trees from the start, any chance that they will sway in the wind or something?

Also you didn't say how you create leaves, I believe that was my original question, since those look really cool.

[Aeros]

Photoshop my friend I'll go into more detail on 0 A.D.'s natural art in the near future and you'll get to see how its made and what else we plan to do with our flora... if that'll be included in the upcomming article I mentioned. If not it'll go on our site as a developer article.

I'm not sure about swaying animations or things like that, if do that I'd like it to be real and mimick real wind, which means they would have to sway directionally and not in random directions the way its done in other games, also I tend to favor still trees since if you have things like plants and trees and grass moving all the time, not only does it use up significantly more processing power than is necissary, but after a while it can make you dizzy or make your eyes hurt from seeing so many highly saturated / contrasted pixels moving, that and aliasing issues apply so it won't look fluid unless you're playing at a very high resolution. We might try it in the future if theres time, but its not something that'll make or break the natural environment in 0 A.D.

[TheCobra1]

Yeah, you guys have done an amazing job with the trees.

(I don't think you guys have any of the trees on your site anymore.

Edited February 8, 2006 by TheCobra1

[mista_maggoo]

if you make tree swaying sounds or blowing in yhe wind it mite be convincing enaugh...but what do i know?):