Issue: Volume: 31 Issue: 2 (Feb. 2008)

Unleashing the Unreal


With a massive fan base spread across the entire gaming spectrum—from professional PC gamers, to the mod scene, to the casual and console gaming world—creating a next-generation update of the Unreal Tournament series that would please so many disparate expectations was a daunting task, to say the least. Thankfully, the crew at Epic Games came through in spades, producing a first-person shooter and online multiplayer game of unparalleled visual quality. And it’s one that delivers all the heart-pounding, adrenaline-pumping, ultraviolent combat action that players expect, and with the full per-pixel lighting and 64-bit HDR glory of the new Unreal 3 engine.

Unreal Tournament 3, which marks the return of the franchise on the PC and its console debut on the PlayStation 3, also features a new single-player story line, a new race of vehicles (see “Vehicular Violence,” pg. 20), cinematics worthy of the silver screen, updated weapons, and more than 40 maps to traverse as players defend humanity against the alien Necris invasion. The hugely successful online multiplayer series was never sold on its riveting interactive story, but rather, as its trailer promises, on “unprecedented battlefield warfare” and “unbelievable carnage.” And both of those run rampant throughout the title’s six game modes: Deathmatch, Team Deathmatch, Capture the Flag, Vehicle Capture the Flag, Warfare, and Duel.

For Epic, the key to creating a successful next-gen game that would meld the best features of previous titles was to stay the course set by Unreal Tournament 2004. “Adding the vehicles to UT2k4 was a scary change for us at first, but once we nailed the feeling we were going for, it all clicked. In the end, that feeling is exactly what we were aiming for with UT3,” says Epic artist Paul Jones. “The higher gravity and stronger weapons produced more personal, grounded battles, where you can connect with your weapons and vehicles (since they’re really the star of the show). So, when we want to make a change to a franchise staple, we do a lot of testing, and then more testing, and then we test our testing to make sure we’re really sure.”

Nonetheless, Epic’s criterion for making changes was simple. “We asked ourselves two questions: Is the change fun, and does it make the game better?  If it fits both those criteria, then the change sticks,” explains Jones.

In fact, the biggest change gamers can expect is not in the gameplay, but rather in the stunning visuals, character animations, and physics. The game’s futuristic film-noir and sci-fi Gothic settings are a wonder to behold, with huge, Necris tentacles sprouting from the ground and feeder tubes pouring into and infecting the urban landscape, as giant tripod-like Darkwalkers stalk the streets. “There is so much more detail in all the assets. The increase in the number of polygons, the extra realism, the quality of the lighting, and the extra polish put into every pixel of this game shines through in the final product,” says Jones.

Aside from the gorgeous graphics, the other significant change involved the game’s production pipeline, which was revolutionized by the introduction of Unreal Engine 3’s new visual scripting system. Called Kismet, it puts the power of programming into the hands of artists, animators, and level designers. In the past, artists would create a level, set up path-finding points, and so forth, and then turn to a programmer to script the appropriate animations and behavioral AI for each situation. Using Kismet, artists can now set up gameplay situations themselves by building their own scripts using a visual flowchart-like system. Incredibly, Epic says only five percent of its gameplay scripts are written with the help of programmers.

“Unreal Kismet has also opened up a whole new world to designers and artists; it’s been one of the other great changes we’ve introduced with UT3 that has given back more control to the creative side of gaming,” Jones points out. “When these two systems (Unreal Kismet and Unreal Engine) are working in concert, you get fantastic levels and incredible cinematics that come together quickly and easily, and happen in real time, in-game.”
 
Single-Player Story line
The cinematics mainly support the new single-player story line, which follows a grizzled, alpha male named Reaper, who helps his heavily armored dame, Lauren, seek revenge against Akasha, a rogue inquisitor of the Necris alien race who murdered her parents. According to Jones, UT has always had a story line going on in the background, but the action has been the focus online. And the developer did not want to stray too far from the format that has worked so well for the company in the past. Nevertheless, there is more of a story component to this UT, as well as a campaign mode that can be played either off-line as a training mode or online and cooperatively with friends.
 
The latest version of the popular Unreal Tournament series is powered by the new Unreal Engine 3, which enables cutting-edge visuals and gameplay throughout.

“Surprisingly, a significant portion of our player base never takes their UT experience online, and we wanted to make sure that there was still plenty of game available to that crowd,” says Jones. “With this iteration of the franchise, we’re also branching into the console market, recognizing the value of a good couch experience to those customers. The campaign and cinematics are a great middle ground between a full story and online mayhem, and it balances both styles of play.”

The single-player story line also helped drive and direct the development of the many levels needed for an Unreal Tournament game. “People are used to 40-plus maps in our games; that’s an impressive amount of content needed in these days of next-generation assets,” says Jones. The numerous levels are set within five main environments: Liandri mining colony, an Asian-influenced alien set, a crumbling ancient ruins set dotted with Turkish architecture, the Necris world, and a humanoid urban set featuring burned-out cities and twisting industrial complexes.

“We set out to create environment assets that were modular, not only in their construction, but also in how they sit together with adjacent sets. We created the Liandri and human urban set as a hub from which the other sets (Asian and Necris) could be combined effectively, multiplying the number of unique arenas that could be built,” Jones explains. “Once the level was ready to be meshed out, decisions were made on what makes the map memorable—sometimes it’s the huge, blinding, sandstorm that rolls in, another time it could be dramatic lighting, sometimes it is the vista that surrounds the map. That’s the beauty of working on a title such as UT3; there are a lot of creative visual options to work with.”

Of all the sets, Jones says the Necris environment is probably the most visually striking. The Necris technology is invasive and insidious, fusing itself to the environment with giant capillaries that spew a substance called Nano Black, slowly making its own twisted version of the world bustling with alien technology. The resulting, mutilated environment was inspired by Turkish and Gothic cathedral architecture. “It proved to be a versatile set, instantly giving the environment a unique feel,” he says. “Both the environments and the vehicles follow this vein of technology in their design and architecture, and with the tentacles able to take over any host, we are able to extend the Necris visual set easily.”
 
Character Modeling
There are three forms of characters in Unreal Tournament 3—human, beast, and robot—from which the game’s five teams are derived: Ironguard, Necris, Ronin, Krall, and the robots of Liandri. The crew used Autodesk’s 3ds Max and Maya to model all the humanoid, alien, and robotic characters, as well as most other organic and hard surfaces. When modeling organics, the team tends to use Pixologic’s Zbrush or Autodesk’s Mudbox, depending on the preference of the artist. Ultimately, though, the imagery is imported back into 3ds Max for processing the normals and UV layouts. All the characters in UT3 have four levels of detail (LOD): 10k–15k, 7k–8k, 2k–3k, and 900 polygons at the lowest end. The highest LOD character models appear in the game cinematics as well as in the PC version, when users max out the detail settings.

At Epic, the team could often avoid creating a more geometrically detailed character by exploiting the complexity of the character’s silhouette and, more importantly, how the negative space between the various elements is used. The Necris, for example, have minor shapes that rise off the main silhouettes, making them more easily identifiable from a distance and more convincing up close. In the case of the Necris, it’s the pipes that help achieve this instant recognition. For the Krall, a snarling, lizard-like beast with cloven hooves, it’s the horns. These instantly identifiable earmarks, combined with normal maps, help create the illusion of a higher level of detail. Using these techniques, the team found it could use the in-game character models, at the highest LOD, for the cut-scenes.
 
The visual quality of UT3 and its expanded story line make it a game for all types of platforms—PC, console, single-player, and online multiplayer

When modeling the characters, such as Reaper, Lauren, or Malcolm, the artists’ guiding philosophy was to make each convincing but larger than life, adding details such as scars or face paint that describe the character’s backstory or tell a tale about his or her battle experiences or personality. “We start from what’s more realistic, then look for opportunities to make exaggerations to convey a certain type of character or attitude,” explains Jones. A full character comprises nine customizable body parts: head, helmet, face mask, goggles, torso, arms, shoulder pads, thighs, and boots.

Of course, with every character encased in heavy body armor, pinching problems around troublesome joints—the universal bane of modelers these days—became a frequent challenge, especially around the shoulder area. To overcome this issue, artists would create a rough base mesh of the character without armor, and then model the rough armor elements over it. This helped maintain good anatomical proportion, says Jones, while allowing the modeler to quickly determine whether the armor needed tweaking to function correctly.

“Because the armor elements still have a relatively low polygon count at this point, it’s much easier to go in and make quick adjustments—another huge advantage to modeling this way. It becomes significantly more time-consuming if this ‘primary check’ is put off until the high poly model is made,” says Jones.
To further facilitate the smooth articulation of the body armor, the artists modeled many of the plates as separate, individual pieces. While done primarily to make the pieces interchangeable on a character, it also made it easier to select elements and assign weights during the rigging, so that the segments would not intersect during animation.

According to Jones, the most difficult Necris characters to create were Loque and Akasha, though for different reasons. For Loque, the challenge was modeling the detail in his suit: the various pipes, couplers, and pieces of armor that are necessary for conveying the considerable weight of the suit. The final high-res model of Loque was roughly 30 million polygons, from which deriving his normal maps “became a nightmare.” This decision to saddle Loque under a mountain of metal also influenced his appearance, demanding a more muscular, Herculean physique that could handle the extreme weight.

Akasha, meanwhile, was less detailed than Loque but presented a challenge of another kind. The goal with Akasha was to make her not only attractive, but tough. This was a difficult look to achieve with a female character because the subtleties in facial structure, like the jawline, the bridge of the nose, and cheekbones, can greatly change the personality that the character conveys. “After technically finishing Akasha and seeing her in-game, she underwent a cycle of polish, with additional model and texture detail further enhancing that attractive yet tough look.
 
Rigged for Battle
To rig the characters, the artists again used Maya. The multifaceted, rigid-body armor is weighted to specific bones, which allows animators to adjust their positioning and deform them realistically with the underlying body parts. Occasionally, even with rigid parts, riggers did soft weighting between multiple bones to make them flex a bit, preventing them from colliding with other body parts. This not only keeps the bone count low, but also reduces the animation data without compromising the realism of the character’s movement. While the Necris and more beastly characters may look more complicated in their rigging, they share the same skeleton and most of the same animations as the humans, which reduces the overall memory footprint.

For the facial performances of the cut-scene and in-game characters, artists built a facial rig comprising bone poses, set-driven keys in Maya, morph targets, normal-mapped wrinkles, and complex scripted expressions to combine the phonemes. The team then turned to Image Metrics, a company specializing in performance-driven facial-capture technology, to acquire live video of the actors lip-synching to pre-recorded audio. This information was then translated into facial data and imported into OC3 Entertainment’s FaceFX, a facial animation package now fully integrated into the Unreal 3 engine, for driving the facial rigs for all UT3’s characters. Artists later tweaked and exaggerated the facial animation, added eye tracking, and animated the normal-mapped wrinkles to create the final effect.
 
Despite the powerful capabilities of the Unreal 3 engine for creating realistic imagery, the artists at Epic opted for an exaggerated look for the game characters, keeping the overall look consistent with the previous titles in the series.

Epic also employed motion capture for nearly all the cinematic animations and quite a few of the in-game animations. The company has its own motion-capture stage featuring a 36-camera Vicon MX system. For cinematic sequences, the team usually has as many as four characters performing on stage during a mocap shoot, although the system can handle more. Using Vicon’s IQ software to capture the data, the crew then uses Autodesk’s MotionBuilder to target the data onto the characters. All the mocapped animations are massaged using traditional keyframe techniques, to exaggerate and stylize the final movements. According to Jones, Epic always tries to avoid “raw mocap.” Physics simulation, from Ageia’s PhysX, provided ragdoll animation as well as furnished such unique behavioral animations as feigning death: players slump over and pretend to be dead.

Underlying the characters’ body armor, of course, is a variety of battle-singed garments, which artists animated using bone-driven cloth. For the flapping and billowing flags in the Capture the Flag mode, animators used vertex-driven cloth that was set up in-engine. The vertex-driven animation moves a single sheet of polygons and deforms each vertex based on momentum, wind, and other factors, yielding realistic cloth motion for any object consisting of a single sheet of polygons. The bone-driven cloth animation uses physics to drive a string of bones bound to a piece of weighted cloth­—ideal for thicker cloth such as leathery armor or even ponytails, which will deform realistically around a character’s arms and legs.

All told, the core animation set for UT3 consists of more than 120 animations. In addition, the game features many character-specific and situation-specific animations, as well as nearly 150 single-frame poses used to tweak the core animations. All the animations and poses are handled by a tool set of controllers called the AnimTree, which determines which animation to play in certain situations. “These controllers can be used to play run cycles, physics simulations, aim offsets, and upper-body only animations, and allow for the creation of any custom controller we can think up,” says Jones. “The hardest animations to create were probably the hoverboard animations, which weren’t that complicated, but they relied so much on physics that it took a lot of trial and error and going back to the drawing board to get them to look correct.”

Epic’s animation pipeline harnesses the full gamut of Autodesk products, including MotionBuilder, Maya, and 3ds Max. MotionBuilder was used to target the mocap data onto a character, as well as to do some timing adjustments and looping. The majority of the animation—mocap or not—was done in 3ds Max or Maya, depending on the animator’s preference. After import into the engine, the animation was further tweaked, timed, and blended with Unreal Engine 3’s AnimTree system.

One of the new pieces of equipment in UT3 is the hoverboard—essentially a hovering skateboard that players must ride once they’ve captured the flag in Vehicle Capture the Flag mode, lest they be forced to carry it on foot. “The hoverboard was a unique vehicle to animate. It didn’t follow any of the pre-existing conventions developed for previous modes of transport,” says Jones. “It was used as a test bed for a new motor-driven physics system for characters. Basically, the character you see on the hoverboard is a physics ragdoll, but the physics joints have motors on them that are always trying to keep it in a certain pose or match a certain animation. This way, physics can throw the character around a little and make his knees bend and react, yet still play an underlying animation.” The group later found other uses for this system, such as for hit reactions and death animations.
 
Character Texturing
The shader system for the characters comprises a wide variety of bitmaps for the head and body, including diffuse, normal, specular, specular power, Fresnel, transmission, and transmission mask maps, which at the highest level of detail are normally 2048x2048. For the metallic Necris surfaces, Epic used additional bitmaps, such as gradient, cube, and a special falloff map to give specific parts of the armor a car paint look, which has a depth to its overall appearance.

After a player customizes a character’s textures, the code combines all the separate textures used in the customization into the minimum number of textures needed for the in-game characters. Since character faces tend to receive the most scrutiny, both in-game and during the cinematics, the team reserved a 2048x1024 region on the bitmap for the face alone. Transmission masks and Fresnel maps were particularly important in capturing a sense of depth and the subsurface scattering of light, especially in the skin and other organic surfaces.
 
The game characters, including the mercenary Malcolm, were created in 3ds Max and Maya. All the characters have four levels of detail, ranging from 15,000 to 900 polygons.

Most characters also sport reflection maps, except for strictly organic creatures. For example, the Krall, whose armor is made from organic elements, wouldn’t require reflection maps, whereas the Ironguard and Necris would need them on their metallic surfaces. Given the frantic pace of UT3’s gameplay, Epic avoided painting or modeling damage effects for the characters, and instead concentrated on creating custom death effects. For example, the blobs of bio mass discharged by the Bio Rifle makes the character dissolve away in a kind of acid bath; the Shock Rifle Combo sucks characters into a mini black hole before ripping them apart into small pieces; the rockets fired from the rocket launcher splatter a character into flaming body chunks; and, finally, the Link Gun laser beam strips away flesh and armor until the victim’s skeleton is laid bare.
 
Killing Fields of Dreams
From the ominous, chiaroscuro lighting of the twisting industrial complexes to the scintillating light in the snowy ice-scapes, to the diffuse, scattering light through translucent forest canopies and blinding sandstorms, UT3 harnesses the full power of the Unreal 3 engine for its new lighting system.

“The lighting system enabled us to make some truly beautiful environments and gave the artists lots of control to shape the level’s lighting into something special,” says Jones. Levels generally use direct lighting and some overall bounce light, as well as point lights placed in areas for additional radiosity-style shading. Nevertheless, the artists still use many tricks to maintain the balance between performance and visual beauty. For instance, the reflections are cube maps that look great and have little cost other than the time needed to author the textures.

For the god rays piercing the forest canopies or the beams of light knifing through the smoke, fog, and mist, artists used simple, cone-shaped primitives with a translucent falloff material applied to them that hides the edges of the geometry. In addition, the light beams are able to compare their depth to the depth of other pixels being rendered, enabling them to blend out where intersections occur. As Jones points out, this technique has many applications and removes the old problem of assets visually clipping.

To make the foliage react to wind, concussive effects, and other forms of contact, the artists applied a very basic wind vector as well as additional pixel-shader wind, using a distortion shader to create more of a “‘rustling leaves in the breeze” effect. The team also used SpeedTree, Unreal Engine 3’s tree and plant solution, to create foliage.
 
UT3 features five main environments, each with its own architectural style.

For the rippling pools of water interspersed throughout the jungle environment, Epic used a materials effect. The water surfaces reflect a cubemap, giving them a wet, liquid appearance. By panning a wave-shaped normal map inside the water material, the reflection is offset according to the directions specified by the normal map, creating the illusion of actual waves in the liquid.

According to Jones, the Unreal Engine 3 is a true WYSIWYG content creation tool. The visual materials editor is a node-based system that gives the user the ability to create any next-gen material using normal maps, specular, reflections, diffuse, and masks. Along with FaceFX for facial animation and physics from Ageia PhysX, Unreal Engine 3 also seamlessly integrates Allegorithmic’s ProFX middleware for procedurally authoring complex textural effects.

Epic Victory

The free-form, unscripted gameplay of a huge, multiplayer LAN game such as UT3 makes AI programming a huge challenge. The AI has to be able to navigate anywhere in the level and handle a multitude of unpredictable situations without hand-holding by the level designers. The complexity of the game rules and plenitude of options available for weapons, vehicles, different routes, and strategies for winning also complicates the programming of convincing AI.

“Making sure that the AI players ‘feel’ human is also difficult. We’ve spent countless hours tweaking how they move and shoot to make them as indistinguishable as possible from human opponents,” says Jones.

Aside from the “unbelievable carnage,” the Unreal Tournament franchise’s appeal was also built on its extreme friendliness to the mod community. UT3 ships with a fully featured level editor, which includes animation, particle system, and physics tools—the same editor used to make the game. Additionally, the developer provides all the UnrealScript game code and an UnrealScript compiler for creating the mods. “We’ve spent a lot of time in the UT3 game code, making sure that it is well designed for modding,” says Jones.

From consummate PC gamers, to casual console gamers and avid modders, Unreal Tournament 3 is a feast for all. Though it’s often said that trying to please everyone is a fool’s game, it’s certainly a game Epic played, and won, with style.
 
Martin McEachern is an award-winning writer and contributing editor for Computer Graphics World. He can be reached at martin@globility.com
 

VEHICULAR VIOLENCE
 
The game’s battlefields rumble under the heavy-metal tonnage of hundreds of Necris and Axon (human) assault vehicles; this time, many of them have more curved and animated surfaces to maximize the potential of the Unreal engine. The visual upgrade included the addition of a full-damage system, integrating morph targets, detachable parts, a damage shader, hit-location-specific particles, a location health system, and customizable explosion and vehicle death parameters.

The Leviathan, a powerful five-man mobile assault station with five turrets, was the most complex of the Axon vehicles to create. A vehicle of huge scale and one that is required to hold five players (four turrets and a driver) as well as an integrated super weapon capable of mass destruction, the Leviathan posed quite a challenge from initial concept right to the end. “Its immense size caused levels to be redesigned to accommodate it,” recalls artist Paul Jones. “Ultimately, what makes it all worthwhile is the awesome sight of seeing the articulation and transformation of the vehicle parts as the super weapon deploys.”

The more polished, angular, and insect-like Necris vehicle design emerged from a desire to forge a stark contrast to the mechanical, beaten-up metal of the existing set of Axon vehicles. Early on in production, a smooth, composite shell material was developed for the alien vehicles, setting the style for all new units. Powered by a glowing, moving energy ball and the signature tentacles, the Necris vehicles were born.

“All of them proved a modeling challenge, especially with the frequency of complex, compound curves and intersecting shapes. However, with the organic nature of the Necris vehicles, the normal maps helped immensely in producing the final look of the vehicle,” says Jones.

None of the Necris vehicles proved a greater modeling and rigging challenge than the towering Darkwalkers, which stand on a tripod of Nano-fueled tentacles and dominate the landscape like the giant tripods from HG Wells’ War of the Worlds. Its spider-like legs were animated procedurally in-engine using a form of spline IK.

To get the Darkwalkers’ legs to move, the artists first animated a single-step animation in Autodesk’s Maya. The programmers then used that motion as a reference to move effector nodes that would adjust to the terrain. This way, the nuances of the leg animation could be kept, while the leg would be able to step to any point within a certain range from the body without stepping through the terrain or an object. Finally, in-game physics forced the leg to follow the moving effector nodes. This gave the leg a powerful step that, while remaining true to the source animation, felt fluid and organic as it moved across the landscape.
 
The vehicles in this version of Unreal Tournament have animated surfaces that take advantage of the new Unreal 3 engine. Damage is shown only in the areas where the vehicles have been hit.

Another spider-like vehicle, more lithe and fast moving than the Darkwalker, is the Scavenger, which scampers across the landscape on three short, spindly legs, occasionally rocketing forward with its legs spinning like razors on all sides. The Scavenger can retract its legs and spin them around the vehicle during an attack, so the physics controllers had to blend on and off to allow the animation to take complete control of the leg.

The new and improved vehicles, with their universal destructibility—featured most prominently in the Ageia PhysX-enhanced PC version—also received a new damage system, one deliberately designed to enable gamers to anticipate when a vehicle was about to disintegrate or explode.

In addition to the textures painted for the damage shader, each vehicle features a wide variety of maps authored at 2048x2048 (though the number usually depends on its physical size). The Leviathan, for instance, which is the game’s largest vehicle, has a total of 12, including diffuse, normal, specular, and damage textures. “Over the course of the project, we decided the visual state of the vehicles should represent their health rather than a traditional bar,” says Jones. The group set up a parent shader through the shader system, along with a child shader, so that if a change was made, it would propagate to all the vehicles in the tree and save time in alterations. A vehicle’s damage is revealed only in the areas corresponding to the locations in which they are hit, thanks to a set of custom masks.  —Martin McEachern
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