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Posted by Frankie at 3/23/2007 5:22 PM PDT

We talk about atmosphere and scale in this Week's Update, and of course it wouldn't be an update without a mention of water, would it?

Let us discuss atmosphere. Let us begin with the simplest question of all. Why is the sky blue? The answer is of course infinitely more complex than the question. The sky is blue, because of Rayleigh and (to a far lesser extent) Mie Scattering. Named after Lord Rayleigh (John William Strutt was his civilian handle) and Gustav Mie, respectively. This kind of light scattering happens when light travels in transparent solids and liquids (think pollution particles, for example) but also through gases. That scattering, of ostensibly white sunlight, through Earth’s atmospheric mixture of gases, produces a distinctly blue sky. But we’re just as interested in the dirt as the blue sky.

In Halo 3, we simulate Rayleigh and Mie Scattering by creating “virtual” pollution and air and passing “real” light through it for a realistic effect. I am massively simplifying this explanation for two reasons. One, I want to make this enjoyable and clear for you, dear reader, and two, I barely even understand what I’m saying. For example, Rayleigh Scattering relies on the principle that the distorting particles be smaller than the wavelength of the light. I just don’t want to go there at this time of morning.

At its very simplest level, your see Rayleigh scattering when you look from about 45 degrees to straight up, and you see Mie scattering when you look straight at the horizon. Naturally the further you can see unobstructed, the more pollutants will enter that distance, and the more haze is created. Unless you live in Los Angeles, in which case you can probably detect Mie scattering by looking across the street.

You can get an idea of what I’m talking about by watching the E3 trailer. Across the huge artifact that the Chief discovers in that trailer, you see the air start to haze over, as tiny distant particles change the color, quality and transparency of the air. When you turn off our simulation of Rayleigh and Mie scattering, the distant objects pop out and any sense of distance or scale is ruined. You might as well be looking at an object the size of the dish in Ascension.

The need for realistic distance drawing is vital in Halo 3, because of the sheer scale of our maps. The distant mountains in that E3 trailer are absolutely real geometry. You can detach the camera, fly out to them (which would take about fifteen minutes even with our camera’s “gas” button held down) and see that they’re even textured properly. This is a function of the nature of the Halo 3 engine, and testament to the 360’s horsepower. It means we don’t have to “cheat” as much with fancy skyboxes and obfuscation.

Don’t get me wrong – the mountains on the far side of that artifact in the trailer aren’t very detailed when you eventually get there, but for accurately creating a sense of scale and realism, nothing beats enormous scale and vital realism.

You can see a similar effect in real life by looking at distant mountains on a clear day. No matter how crisp the air, the mountains take on a bluish tint as the tiny particles of pollution and other matter scatter the light being reflected or emitted from distant objects.

These techniques appear in many levels, since technically most of our levels contain big, open spaces, at least part of the time. There are smaller scale applications too, such as humidity in a lush environment, and dust in a desert clime. It has fewer applications in multiplayer, but it is creeping in where required.

If you want to read more about the science of Mie and Rayleigh scattering, check out this much better explanation here: http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html

And speaking of Multiplayer, Steve Cotton has started a serious graphical polish on Jub Jub, one of the last maps to get that kind of lovin’. He has the color scheme down, and it’s broody and atmospheric, but he’s started adding real detail and texture, including a brilliant new take on how Forerunner tech, can intertwine in a groovily serpentine fashion, with natural environments. It’s going to be a favorite mid-sized map, in the vein of Lockout, but it’s not my favorite. That honor goes to High ground right now, as far as I’m concerned, but a couple of others are vying for my malicious intentions.

Weekly Water Update

There have been a few changes to water recently. The water tech has been handed off pretty much by the graphics programmers (often very artistic themselves) to the artists “proper” and they have been tweaking and tuning it in every level to make it more delicious. Honestly, I care about it more than they do because of my Rain Man style obsession with the stuff. One difference I noticed on High Ground is that as well as normal waves on the ocean, there are the mini-ripples of wind on the surface of the larger, tide-generated waves. A small detail, but a convincing one.

Even more convincing is the coloring and reflection work being done on the water surface. Water isn’t really clear and transparent until you’re looking directly down – at an angle, it’s a darker version of the blue of the sky, or picking up colors from rocks and trees reflected in it. But it was Joe Staten who spotted the best new water feature (I would describe him as about 85% less excited by it than me) which is a waterfall from a very early level, where the water flows smoothly and slickly over some big, smooth boulders, and then cascades more energetically down the larger drops – to end in a convincing mist and splash as it hits the main body of the river. That effect is implemented in Valhalla already. I can’t actually remember what it looked like in the Alpha version now. One other water feature is an area of flat rock, with a millimeter thin film of slow movin’ agua. You will be pleased to know that I am running out of water areas to describe. I’m going to have to move on to mud and snow and other soft surfaces next.

A Flock of Seagulls

There are two aspects to this story, one literal, one metaphorical. I’ll start with the latter. Genius programmer Damian Isla is working on “flocking behavior” for distant battles. There are certain parts of the game where large scale air battles are going on in the distance, and the most convincing way to do that is to use real craft having real battles. Now, these particular ones are for show rather than interaction, but they should look convincing. Damian’s been tweaking the behavior of all these craft – I won’t name ‘em, but you can probably guess what various kinds are going at it – so that they have visually convincing fights.

That might sound like a cheat, but it’s not. When you’re in aerial combat, regular AI will be used against you, but that doesn’t necessarily look exciting from that kind of distance, so flocking behavior is used. The craft you’re seeing are real – and if they shoot each other, they explode – as a matter of fact, if you had a rocket launcher and got lucky from that distance (think miles), you’d be participating in the battle. And the battles look amazing. It’s all about immersion.

But on a more literal scale, one of our contract 3D artists is working on birds. So far I’ve seen seagulls and what appears to be some kind of cockatoo. Both kinds flock, wheel and fly in very large numbers. Who knows what those numbers will grow or dwindle to in the final cut, but right now the demo was about 50 seagulls wheeling and cawing above a cliff top, and looking remarkably like Discovery channel footage of an otherwise boring scene.

Perhaps more importantly, the seagulls and cockatoos can (at the moment anyway) be shot. They will then fall, individually out of the sky and you can go take a look at how detailed they are. Believe me, we’re not wasting any processor cycles on this stuff, so if it causes a hit, out it goes, but hopefully they’ll be there. There are at least two keen hunters on staff who want to go grousing in Halo 3.

In combat, the scale is just as large, but the AI is different since it’s tuned for fun and challenge rather than grand spectacle. No point in a glorious sequence of barrel rolls if they serve no gameplay purpose.

And gameplay is there. Seriously. The designers would scoff at that opinion given how much polish time they have left on these encounters, but already, gameplay has reached new heights. And I don’t mean Halo 3 – I mean for the entire series. This part is going to sound like hyperbolae, so I’ll reinforce the fact that this is merely my opinion:

Halo 3 encounters are more fun, more challenging, more varied and more enjoyable than those in Halo or Halo 2. The interplay and strategies created among the various Covenant foes is just thrilling. One weird thing that I just can’t get used to (in a good way, I mean) is the fact that you have to plan for multiple encounters in one location. You can see a group in the distance, and head down to fight them. You could toss a grenade to get the party started – but here’s a hint. Between you and them and the tumble of rocks and scree between you, I happen to know that a Phantom is going to drop off four Grunts and a Brute Chieftain. The Phantom itself is going to start laying down fire on you, so my suggestion is to bide your time, wait for the first Phantom, and take care of that before irritating those guys way down the hill.

The AI on the opponents is more interesting too. Even a lone Grunt can be a nasty challenge. Actually, a lone Grunt is sometimes a cornered Grunt now. You’ve been warned.

And I’ve heard more than one Bungie staffer say the same thing at the urinal (that’s where we talk, and yes, we call it the water cooler). You’ll see them come in, laughing and peeing, peeing and laughing, as they recall a particularly brilliant gameplay moment.

Now wash your hands.

The contract 3D artists are working on the little detail touches that are going to make spaces feel real and lived in. That could be anything from an electronic wall panel (complete with a smashed and damaged state) to a shiny military latrine. It’s fun to watch the look of concentration on an artist’s face as he puts the finishing touches to a gleaming, stainless steel toilet.

But speaking of Damian, he and a couple of other folks have been slaving away on a cool Easter Egg. Most of you will never see it, but if you do, you’ll maybe think back to this, and say, ooh, that musta been the thing Damian made.

Now, back to campaign for a moment. I was playing a level, let’s call it a quarter of the way into the game. I exit through a very large doorway, emerging from an indoor space, to a large (medium, based on the scale of other H3 locations) outdoor space. I will go ahead right now and admit it’s part of the level that some journalists caught a sneak, and very early peek at during the Alpha event many months back.

I thought it would be as good a place as any to describe the content of an average H3 Encounter. To do this, I made the Chief invincible, detached the camera and flew around counting stuff. Now, remember, this is live, so these guys were all fighting each other, lobbing mortars and dying, so I may be missing a few (Jackals for sure, since they were pinging me pretty good from somewhere), and I definitely saw a Phantom deliver two more ghosts while I was counting, and I literally stopped counting when, after a couple of Marines had been killed – a door on the far side of the location slid open, and revealed a whole passel of jerks. I figure the list below will pretty much give you the idea. Remember that, if you had a sniper rifle or rocket launcher, you could have destroyed any or all of the following in that one, single location. And I am deliberately leaving out a couple of items here, because they haven’t been revealed yet.

Encounter Recipe:

• Scary Post Apocalyptic Environment: 1
• Phantoms: 3
• Grunts: 14
• Marines: 6
• Brutes: 8
• Jackals: 3
• Wraiths: 3
• Ghosts: 6
• Mongoose: 1
• Warthogs: 1
• New version of old favorite: 1
• Chief: 1
• Giant Bad Guy in distance: 1
• Frightening and Inexplicable Maelstrom: 1
• Ancient Forerunner Artifact: 1

Heat above ingredients to heroic temperature, mix and allow to mix and marinate. Check periodically for carnage and extra ammo. Die. Repeat.

Variety being the spice of life, I dropped into our sandbox to look at the different variants of things – special types of Grunts, Brutes, Jackals and so on, but I was surprised to see how many different types of Marine there are. Not just physical types, but also states – there are injured, bloody and disheveled states for them too. Knowing what I know about the plot, that’s hardly surprising.

Battle of the Maps

So Sketch is all up in the forums trying to decide, as Halo 2 enters its twilight years, what the all-time grand champeen of all Halo levels ever is. You can go vote for your favorite, regardless of which Halo game, in these ad hoc polls right now:

Halo 1 Xbox – Part One http://www.bungie.net/Forums/posts.aspx?postID=10368027

Halo 1 Xbox – Part Two http://www.bungie.net/Forums/posts.aspx?postID=10378253

Halo PC Polls - Part Three -- http://www.bungie.net/Forums/posts.aspx?postID=10372435

And we’ll update these polls with Halo 2 maps right soon.

Did we mention that Myth 2 is now available for Gametap? Gametap is that online service that kind of works like the Netflix of old school games, only it's on-demand for instant satisfaction. They've added Myth 2 and 3 to their ever-increasing catalog. Myth 2 was made by Bungie back in 19-oatcake, and is one of the most fun and approachable 'RTS' games ever made, if we say so ourselves. I threw air quotes around RTS, because it's not exactly an RTS - but you should go try it and then mangle up your genre description afterwards. Visit www.gametap.com for more details.

Next week, we’re going to have some very cool content for you, including a new look for the Vehicles and weapons specials we’ve shown you, and an accelerating sense of momentum about the game. So in the meantime, here's Mie scattered flock of Chiefs.