|In Part 1 of this two-part series, we examined the technology behind Microsoft’s new Xbox 360 game console. In Part 2, we look at how one developer, Bizarre Creations, utilized this new horsepower to deliver a breakthrough title.
When Bizarre Creations got behind the wheel of Microsoft’s new Xbox development kit, the developer did an abrupt “360,” which put the group on the road to more exciting computerized gaming.
Two years ago, when Bizarre entered Microsoft’s Xbox 360 race to deliver a release-day title for the console, it chose the road less traveled; in fact, the road didn’t yet exist. And although the software developer experienced its share of bumps en route to next-generation gaming, the trip-which ended with the release of its Project Gotham Racing 3 (PGR3) title-appears to have been worth going the extra mile to produce.
PGR3, the latest entry in the award-winning franchise, expands the features and gameplay that race fans experienced on the second-generation gaming system. The title allows players to create a roster of the hottest supercars in existence, introduces them to the high-definition era, and drops them into a racing world where style rules the road.
“PGR3 takes all areas of the game a big step forward, making the most of the new Xbox 360 technology,” says Peter Roe, technical artist at Bizarre. “In this iteration, you can race the fastest and most exotic vehicles in four landmark cities across the world-London, Tokyo, New York, and Las Vegas-as well as the world-famous race circuit, the Nurburgring in Germany.
|Utilizing the powerful technology within the Xbox 360, Bizarre Creations developed a high-octane game, Project Gotham Racing 3, injecting the title with Hollywood-style effects. Images © 2005 Bizarre Creation
According to Roe, when it comes to PGR3’s road rules, it’s as much about how the player drives as it is winning the races. “You are awarded kudos for racing in impressive and skillful ways, with your driving prowess helping you to progress in the game,” he explains. “You can play how you want-online or offline-with user-defined gaming modes. And through the unique Gotham TV feature, you can tune in online to ‘spectate’ or challenge others as the world watches.”
Without question, the Xbox 360 packs an unprecedented amount of horsepower under the console hood. And Bizarre set out to harness that power within a breakthrough game by redefining the level of detail and realism for the cities and the cars in the racing series. To this end, the artists focused on increasing the texture detail and the multiple texture layers, particularly for the cities, where every building is unique. In fact, just streaming in this type of detail has been a technical leap over anything the group had done previously.
“The biggest technical hurdle we faced on the art side was getting all of the data for each city to stream in as the player races through the city,” Roe says. “We have something like 15,000 unique textures in Tokyo alone, with around 10 million polygons (with the instance mesh included) in the city, and they all have to stream into the memory from a DVD. To put that into perspective, in PGR2, we only had around 1500 textures in Yokohama, and 700,000 polys for the whole city.”
Yet, the group knew that raw polygon pushing alone wasn’t going to make the PGR3 gaming world look believable. “We didn’t just want to throw more polygons at the screen, and it wasn’t just about increased detail,” says Roe. “Rather, we set out to create a greater sense of immersion, and that meant improving the quality of the render, the little nuances that make players believe that they are really driving around the cities.”
The team of artists focused on the quality of those polygons and textures, and that meant looking at how light interacts with objects, how materials for items like wood, metal, concrete, and paint are defined, how the world gets exposed through camera lenses, and how natural phenomena that lenses create-depth of field, vignetting, motion blur, exposure-are introduced. And, according to Roe, the artists were able to achieve all of those effects with the Xbox 360 and still have the imagery running in real time.
“Now that we’re on the Xbox 360, we’ve been able to develop a dynamic renderer for PGR3, allowing us to accomplish things like per-pixel motion blur, high dynamic range lighting and reflections, simulated lens exposure, vignetting, and other cool post effects such as glows and color grading,” says Roe of game’s technical innovations. “The motion blur is the most realistic to ever appear in a game, mainly because we don’t use any cheap tricks that other titles have employed while running on previous hardware. Each pixel has 2D motion vector information that correctly blurs the image depending on angle and depth. It makes the game look natural and realistic.”
In PGR3, the car models comprise between 80,000 and 120,000 polygons, with approximately 40,000 of those used on the fully functioning dashboard and lavish interiors, which are featured in the in-car view. In comparison, the cars for
PGR2 sported only 8000 to 10,000 polygons.
Similarly, the city buildings contain far more detail than those in PGR2. And, the city sizes are expanded: Las Vegas is 2.4 miles long, which is nearly three times the size of Sydney, one of the largest areas in the previous title. “I dare not think about the actual data size,” says Roe. “We have one server that is used just for the texture photos-20,000 photos and about 10 hours of video per city.”
For modeling the majority of the vehicles, the artists used blueprints and CAD reference models provided by the car manufacturers. The group also incorporated detailed and specific photo references, gathered by the group or by Microsoft, the game’s publisher. All this extra detail, however, was expensive: An artist spent between six and eight weeks modeling and texturing each car. This task was done using Softimage’s XSI software, while texturing for the vehicles, as well as for the crowds and cityscape, was done within Adobe’s Photoshop program.
|The quality of the car and city models and textures, as well as the lighting, was a prime focus of the artists while creating the graphics.
To model and animate the crowds, the artists employed XSI; for the cities, they used Autodesk Media and Entertainment’s Maya and in-house tools. Roe notes that toward the end of the game’s development, the city scenes were extremely large, and the group was frequently exceeding the 2gb limit allowed by a 32-bit application. To overcome this issue, the tools team at Bizarre created codes that made the data management easier to handle and control.
To build the virtual cityscapes, the artists first blocked in each building with the correct dimensions but no detail, this based on reference photographs the group took during its many research trips. Once the city artists placed all the objects, they began turning the many thousands of photographs into diffuse, specular, and bump-mapped textures, which they applied to the simple objects. Then, they textured the objects and added windows and columns, slowing fleshing out each location.
As this construction was happening, other artists were making and placing lampposts, phone boxes, traffic lights, and other extraneous “city” objects. The team also modeled and textured the road surface, adding cracks, dirt, oil stains, and road markings for added realism. After the road surface was in place, the barriers for each route were added, along with the crowds, grandstands, and other “racification” details. “It was a long and labor-intensive process, but it was a real pleasure when we saw the final cities in the game,” says Roe.
Without question, the group was able to shift PGR3 into high gear by taking advantage of the new graphics capabilities enabled by the Xbox 360. For example, the new pixel shaders allowed the artists to create complex and realistic materials for all the in-game objects. Each building is affected not only by diffuse, bump, specular, and reflection maps, but also by textures that define (in the pixel shader) the type of material used to construct each building. Wood, metal, brick, plastic, and glass are all rendered with their own distinct material properties that affect the sun, horizon, and environment speculars, as well as the reflective and specular fresnel falloff, roughness, and gloss. What this means to the game is that the cities in
PGR3 react realistically to the sun and the camera viewing angle.
“The lighting tool that we developed for the Xbox 360, with fully occluded bounce light maps, gives amazing depth and volume to the cities,” explains Roe. The lighting tool, which was multi-threaded, utilized most of the office computers at night to churn out a whole city in just over two hours. In comparison, it took 14 hours to process the lighting for a city in PGR2, and that involved just vertex-based lighting.
Bizarre did, however, make good use of some of the powerful vertex shaders for the Xbox 360 in the imagery and effects. “The crowds are all fully animated, with two bones per weighted vertex and with thousands of animated crowd characters-which are individually made from our ‘mix-n-match’ modeling system,” he says.
Project Gotham Racing 3 features some of the world’s fastest cars, which were realistically re-created. To accomplish this, the artists used manufacturers’ blueprints and CAD models as references.
Moreover, the group created all the barriers in PGR3 as deformable instances that use bones to deform their shape. As a result, the artists applied sections of barrier fence and instanced them all around the track, using bones to deform the barriers around the corners. According to Roe, this saved lots of vertex data memory; this was key, since there are roughly 7.8 million triangles in the barriers within Tokyo alone.
So, how does PGR3 push game graphics to a new level? According to Roe, the realistic motion blur especially stands out. “I think it’s the first game to do it so realistically,” he says. “The HDR exposure control is unique too, with only Valve’s
Half-Life 2: Lost Coast demo using similar technology.” He also points to the detail in the cars and cities, plus the amount of textures, as other graphic highlights. “We’ve done things with this game that are usually associated with Hollywood-style effects: large crowds that react dynamically to in-game events, complex lighting and materials, and extremely high-resolution geometry on the cars and cities,” Roe notes.
Roe says the team tried to take all the best elements of PGR2 and build on them. “The fast cars, beautiful cities, well-adjusted [vehicle] handling, and the compelling single and online experience are all present and correct in PGR3,” he says. Also, the crew added new features such as improved integration of the Xbox Live feature into the single-player experience and a custom route-creation tool that adds to the longevity of the
“The three cores of the Xbox 360 have allowed us to develop and enhance the racing genre with more intense sound effects, graphics, and physics. The level of immersion afforded by this extra detail can’t be underestimated; you really start to feel like you’re at a real racing event in a real city with real cars and competitors,” says Roe. “And with the possibility of tens of thousands of spectators watching [Xbox] Live games, the gameplay will be so much more intense. It will be interesting to see how players react to it all.”
The game also sports a freeform camera/picture Photo Mode that can be accessed at any time in any race. “We have made a lot of the effects available for the player to adjust for themselves in Photo Mode,” says Roe. By controlling the camera like any real camera, the player can alter the shutter speed, aperture, focal length, and exposure, as well as other post effects like color, brightness, contrast, and sepia tinting, to take photos of the cars and the cities. Photo Mode shows the length we’ve gone to in making the game look and feel as real as possible.”
This realism becomes especially clear, as the game-as are all 360 titles-is in high definition. “Rendering those extra pixels lets players see all the detail that we put into the game, but it also shows flaws,” says Roe. “So we spent a long time bug-fixing the cities and the cars, because errors like gaps in the mesh or texture stretching issues that weren’t apparent on standard-definition TVs became glaringly obvious on large LCD displays in HD.”
So, buckle up. It appears that next-gen gaming is going to be an amazing ride.
Karen Moltenbrey is the executive editor at Computer Graphics World.