Issue: Volume: 26 Issue: 7 (July 2003)

Cover story: Tron 2.0


By Martin McEachern

Long before The Matrix portrayed reality as the elaborate construct of an intelligent computer, cyberspace was born on the big screen in the 1982 release of Disney's TRON. In the film, computer hacker Kevin Flynn was digitized and thrust into a parallel universe inside a computer where programs were personified in the likenesses of their creators and forced, by a tyrannical Master Control Program (MCP), into gladiatorial combat on an arena known as the Game Grid. Aided by a security program named TRON (The Real-time Operating system Nucleus), Flynn defeated the MCP and returned to the real world.

A milestone in both cinema and computer graphics, TRON emerged during the video game craze of the early '80s along with the cyberpunk movement and the proliferation of personal computers, which collectively fueled a groundswell of awe and wonder about the inner workings of computers. For four fledgling production facilities, the film was an opportunity to spearhead computer graphics' foray into the movies. Robert Abel & Associates created Flynn's vector-drawn persona in the computer world; MAGI used a method of adding and subtracting 3D primitives to create the now-iconic light-cycle sequence; Digital Effects generated Bit, a pulsating octahedron helper bee that is the forerunner of all CG characters; and Triple-I constructed the insect-like Solar Sailor using a polygon modeling system that still underlies current technology. Together, these companies pushed the boundaries of early computer graphics to produce a minimalist spectacle of geometric shapes and vector-based imagery.

Due for release on August 26, more than 20 years after the film's premiere, TRON 2.0, a first-person PC action game developed by Monolith Productions and distributed by Buena Vista Interactive (a Disney company), takes players back to the Game Grid in a modernized version of TRON's distinctive cyberscape. To create a glowing, wireframe world that resembled the original, Monolith's artists not only had to simulate the antiquated computer graphics used in the film, but also develop innovative techniques to emulate non-CG effects—such as, backlit, composite photography—that helped portray the filmmakers' unique vision of a digital universe.

TRON 's lightcycles, among the most memorable elements in the film, were renovated and remodeled by Syd Mead, who also designed the originals. All images ©2003 Disney. Courtesy Buena Vista Interactive.




In fact, the film artists fashioned many of the neon-edged objects, the luminescent eyes, the flesh tones, the circuitry of the characters' body suits, and even the aliasing in the images by hand-painting thousands of mattes to exclude portions of each black-and-white frame before they backlit and re-shot them with the appropriate color filter over the camera lens. According to TRON director Steven Lisberger, it was the synthesis of digital and analog techniques that gave the film's images a "soulful quality."

For the Monolith team, the task of capturing the essence of TRON's hybrid effects with modern digital tools—a majority of which have been tailored to generate photorealistic imagery—required both artistry and technical ingenuity. In fact, the latter included innovative texturing methods and a Microsoft DirectX-based TRON "Glow Effect" developed by Monolith and nVidia specifically for TRON 2.0. The result is a computer game that fully realizes the original vision for the motion picture.

Set in the present day, TRON 2.0 begins with the apparent abduction of computer scientist Alan Bradley, who, after creating the original TRON program 20 years earlier, has perfected an AI routine called ma3a, which can translate genetic code into binary code—and transform a person into a computer program. Suspected in the kidnapping is Future Control Industries (fCon), an Internet-based company bent on appropriating Bradley's technology so it can digitize specially trained hackers, called DataWraiths, and infiltrate the world's computer networks from the inside.

Armed with modern-day tools, the Monolith artists met the challenge of retaining the unique appearance that sets TRON apart from all other films. While adhering to the original vision for the groundbreaking film, they generated imagery that not only mimic




Players assume the role of Bradley's son, Jet, and enter cyberspace as a rogue program to find his father, foil fCon's plot, and neutralize a highly virulent fCon operative named JD Thorne. Jet's journey takes him through 30 levels spanning the gamut of modern system locales, from the bustling Internet City Hub aglow in a Vegas-like opulence, through the 'Net's seamier underbelly, to the fabled I/O towers, and even inside power routers, a PDA, a firewall, and the ancient mainframe. Aided by Byte, a descendant of Bit, and a female program known as Mercury, Jet must fend off the DataWraiths and the ubiquitous ICPs (Intrusion Countermeasure Pro-grams) if he is to reach the fCon server and force a showdown with the shadowy figure orchestrating the corruption.

The most memorable action segment from the film—lightcycle racing—is available at any time during the adventure, once it is enabled. Original lightcycle designer Syd Mead remodeled the cycles for the game, and furnished Monolith's artists with his conceptual artwork for the film to broaden their understanding of the artistic philosophy underlying his designs.

Because geometric simplicity was the cornerstone of the TRON aesthetic, Monolith's artists used a wide range of simple modeling techniques to create levels of extraordinary size, such as the Firewall, which spans more than 200,000 "world units" (more than 3000 meters). "The TRON universe is rare in that you can place a few floating cylinders, cones, or other primitives into a scene, and they'll look appropriate," says art lead Courtney Evans. Populating the game environments with Maya (Alias|Wavefront) primitives, Evans and his team worked with Maya's Create Polygon tool to draw and extrude polygons into basic solids. The numerous inset panels lining the levels also were created through extrusion, while areas dominated by circular forms, such as the corrupted server, were built by revolving profile curves around an axis. For the few organic, amorphous shapes that occasionally infringe on the environment's geometric order, the artists simply lofted curves and used Maya's Birail tool to sweep profile curves along two rail curves.

To illustrate the corruption taking hold in the system, the modelers imposed chaos on the order. As players reach infected areas, they will find digital ruins filled with cracked, fragmented, and crumbling surfaces, usually enshrouded in a green glow. "To accomplish this, we experimented with various automated methods of breaking up geometry, but these processes either created too many polygons for real-time use or they simply didn't produce the desired results," says Evans. Ultimately, the group attained this look by "chewing up" the surfaces manually using Maya's Split Polygon tool, and breaking off pieces and carving out cavities with Boolean operations, which involve using one shape to sculpt another.

After the team created the geometry, it faced an even greater challenge in realizing TRON's signature glow that appears around the edges of the game-level objects. To this end, the artists developed a set of small "edge" textures in Adobe Systems' Photoshop and manually applied them to the models. Then they rendered the imagery using two passes: a regular pass for the colors and textures, and an alpha-channel pass that applied a TRON Glow Effect, developed by Monolith and nVidia, to the edge textures (see "The Glowing Edge," pg. 20).

As the familiar wireframe elegance of the TRON environments began to emerge, the Monolith crew turned its attention to simulating the electrified, backlit glow of the characters' body suits. The meshes for the game's texturally complex main characters were economically surfaced with approximately 2000 to 4000 triangles, while the enemy AI characters were modeled in three levels of detail, the lowest comprising 600 triangles.

A green glow emanates from the cracked surfaces created with Maya's Split Polygon tool to illustrate areas within the computer environment that have been corrupted by a virus.




The artists created the real-time shading and effects for the characters using Monolith's Renderstyle Editor, a proprietary texturing tool that enabled them to tailor the run-time properties of the models, including their ambient, diffuse, and specular lighting; custom vertex shading; alpha-channel maps; and the blending characteristics of multiple texture passes. Most of the characters have one texture map for the head, two for the body and limbs, and one for a reflective, chroming effect on their body armor. And like the edge textures used for the world geometry, these character textures included alpha masks for yielding a similar glow effect during a two-pass render. The first constructs the characters' colors and textures and produces the metallic reflectivity of the body suits by modulating a chrome map based on the camera's reflection vector, while the second generates the glow.

"No real-time lighting information is taken into account on the second pass, so we're basically rendering a material that has its ambient lighting cranked up in the areas where the alpha mask is white," says Kevin Stephens, director of engineering. This "glow" pass is then blurred and blended into the original render pass to produce the finished look.

Not only do the game's CG characters look like their film counterparts by emitting the same TRON glow, but they also move in the same realistic manner. All the bipedal movements, including hundreds of run cycles and jumps, were either culled from Monolith's massive motion-capture library or captured using Motion Analysis' Falcon optical analog system.

The signature Glow Effect radiates from much of the game's geometry, retaining the celebrated look and feel of the film.




Refined and looped in Maya, the data was applied to a game-ready forward kinematics/inverse kinematics rig created by senior character animator Scott Albaugh. This base character rig contained four bones for each limb, four for the trunk and the head, and three for added support. The rig's facial animation system was constructed with 12 bones and featured Maya Set Driven Keys for storing movements of the brows, mouth, and cheeks; a MEL (Maya Embedded Language) script for enabling the head, neck, and eyes to track an object; and a custom MEL interface to Puppet Works' Voice Works for batch lip-syncing.

To achieve a consistent look to the imagery, the team used the same character models and rigs for both the in-game scenes and the 30 minutes of the game's engine-driven cinematics. However, the cinematic animations were motion-captured separately to ensure more detailed, individualistic movement.

In addition to the game models and textures, the unique properties of TRON 2.0's binary biosphere were also defined by the lighting. Once inside the computer, the primary light sources are the myriad glowing panels on the various structures that serve as the game's main graphic design element. Using transparent panels coupled with the Glow Effect, the team was able to mimic many lighting functions, such as hot spots and points of interest. Although light maps were used in the real-world settings of the cinematics, the ubiquitous light sources of the game environments required vertex lighting, whereby lighting information is stored at each vertex of a model.

For one of the most enchanting vertex-lighting effects, the artists created the illusion of a texture constantly streaming off the glowing panels. The effect was created by positioning a pair of bright lights near the bottom vertices of the panel, while leaving the top vertices dark. The artists then mapped the panel with a vertically panning texture and rendered it with the Glow Effect using the Renderstyle Editor's additive blend mode.

Mercury, a female program, exhibits the real-time shading and effects possible with Monolith's proprietary texturing tool.




Because vertex lighting operates at the triangle level, the smoothness of the lighting is directly related to the number and size of the triangles constituting a scene. Therefore, the large, low-polygon geometry dominating the game's levels cast awkward streaks of light where it tessellated into long, skinny triangles—a phenomenon that plagued the game level where the player releases the embodiment of the AI program, ma3a, from her dock. To overcome this problem, the artists placed tiny point lights and spotlights—with their shadows turned off—next to troublesome vertices, or applied flat lighting to the entire polygon and assigned a lighting value by hand.

Monolith artists employed the Glow Effect to enhance Jet's vast arsenal of weapons with a dynamic radiance. Yet, the group relied primarily on its proprietary tool, FXed, to create sprite- and particle-based artillery effects, which were among more than 800 unique special effects created for the game. The tool enabled artists to design time-based events on a timeline, integrating particle systems, sprites, sounds, camera controls, and models and canvas objects (lightning effects and polygon trails) into an "effect group," so they could control the scale and color shifting of each component over time. The team painted the textures for the individual particles in Photoshop, and generated the animated sprites in Maya and Adobe's After Effects. Through FXed, the artists also coordinated the movements of FXed-generated sprite and particle systems with the complex motions of objects in their Maya scenes, thereby synchronizing all the effects with the gameplay.

As an example, the sprite system that underlies the Ball primitive—an octopus-like green goo that is contracted from infected programs—was connected to a complex rig containing soft-body dynamics and Maya's IK spline solver, which the team used to animate the Ball's slithering tentacles. The overall outcome, combined with the Glow Effect and multiple blend modes for the sprite system, was of limpid lime appendages constantly wrapping around Jet's arm. "With each adversary and weapon, we decided to do something a little different, and more complicated," says art lead Matt Allen.

As in the breakthrough TRON film, lighting is an integral and defining element in the TRON 2.0 game, evidenced by glowing panels and characters.




Finally, Allen modeled Syd Mead's new lightcycles using Booleans and Maya primitives, and achieved a smoothly curving surface with light-reflecting highlights by deriving their colors solely from changes in the diffuse, ambient, and specular color components of the models in Renderstyle Editor. "This process created the resolution-independent look you really can't get with texture maps of a fixed size," Allen says.

TRON 2.0 is the first game to use an advanced version of Touchdown Entertainment's Jupiter engine, which greatly outperforms its predecessor used for Monolith's earlier title, No One Lives Forever 2 (Computer Graphics World, November 2002, pg. 32). While the new Jupiter engine is capable of delivering graphics, physics, and animation with greater speed and realism, it is unlikely that many games will harness its power to produce the kind of all-encompassing, self-contained alternate reality that players will explore in TRON 2.0. After all, the game deviates from today's prevailing style of photorealism, offering a unique look that players rarely see in new game titles.

And if the current trend of using computer games as a launching pad for feature films continues, Monolith's visual redefinition of TRON's "digi-verse" could eventually re-emerge once again—on the big screen (see "Modern Makeover," pg. 80). "[Disney] has been very supportive of the game, and we've kept them in the loop at every stage of development," says senior producer Cliff Kamida. Considering Monolith has been mindful of the story line and continuity from the very beginning stages, a TRON sequel or remake may one day be realized.

Martin McEachern, a contributing editor of Computer Graphics World, can be reached at martin@globility.com.

In large part for its glowing aesthetics, TRON is immediately recognizable to most CG enthusiasts. And for the Monolith artists, it was of paramount importance to remain true to the stylized look of the original film—at the center of which are glowing grids, lightcycles, and armor. Perfecting the glowing outlines of TRON 2.0's level geometry proved to be one of the most difficult and crucial challenges facing the team, and one that required a considerable amount of pre-production R&D.

The group initially developed a system that would automatically apply glowing edges to the geometry when the levels were processed in their run-time format. Yet, this system—which worked by subdividing the geometry along its edges and mapping a glowing texture to the edge faces—created far too many polygons for effective real-time rendering. Furthermore, it offered no provision for modulating the intensity of the glow, leaving a hard division between the glowing faces and the adjacent non-glowing faces.

Alternatively, the artists created "edge" textures mapped with an alpha mask that exposed only those areas of the geometry to a render pass that applied a TRON Glow Effect to the image. To modulate the luminance level of the various regions within the mask, the artists painted non-glowing areas black, softly shining areas gray, and "full bright" areas white. The alpha mask was, in most instances, painted white at the outermost pixels and gradually darkened to black near the center. By using various dimensions and resolutions of these textures, the team could rapidly "edge" extremely large objects without accruing the massive polygon count of the automated method, and without resorting to 2048 x 2048 texture maps that were featureless aside from a 10-pixel border. In addition, completely white textures were assigned a Boolean flag (a yes/no identifier) so that the glow pass could ignore the unnecessary lighting information within the alpha mask and simply render the color component of the texture at maximum brightness.

Edge textures were used for a majority of the glowing outlines on the rectilinear walls within the game. For curved, irregular shapes, the artists extruded the outermost faces roughly eight or 16 units inward and applied a small strip of texture to the outer edges. Or, they used Maya's UV Snapshot tool to export an image template of the selected vertices into Photoshop, where they made a custom-fit texture map. Because UV Snapshot was a necessary step in the texturing process of surfaces requiring more detail than just the glowing edges, this method was an efficient means of accomplishing both tasks simultaneously.

"Another favorite trick was to apply a strip texture, with glowing top and bottom edges, to a face, extrude the face out a few times to create 'stair steps' and bevels, and paste a UV map onto the intermediate polygons created by the extrusion," explains art lead Courtney Evans. "It provided instant edging."

To expedite these edging techniques, the artists used MEL scripting and numerous Maya shortcuts. —Martin McEachern




Adobe Systems www.adobe.com
Alias|Wavefront www.aliaswavefront.com
Microsoft www.microsoft.com/windows/directx
Motion Analysis www.motionanalysis.com
nVidia www.nvidia.com
Puppet Works www.puppetworks.com
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