White Paper Physics, Gameplay and the Physics Processing Unit March 2005 “The Next Generation’s most enduring concept is that of the Holodeck (or Holographic Environment Simulator) – a technology that can recreate any chosen environment within the confines of the Enterprise. Designed as a place where the crew can relax and unwind during a long voyage, the holodeck has taken virtual reality to a new level, creating scenarios that appear so real, they are difficult to distinguish from reality.” -- The Next Generation Holodeck Adventures (www.bbc.co.uk) AGEIA Technologies Inc. 82 Pioneer Way. Mountain View, California. 94041 Physics, Gameplay and the Physics Processing Unit 1 Introduction Game consumers today have a lot to be happy about, because computer and console games are better than ever. The platforms are more powerful, environments are more detailed, and characters are more lifelike. There is more action, better lighting, fantastic effects, impressive shadows, more polygons, more pixels and better sound in the games than ever before. Yet somehow, consumers and even game designers are always hungry for more. Leaving the theater of the latest effects-rich Hollywood blockbuster or big-screen animated picture, it is easy to dream of a day when such convincing environmental detail and engaging characters come to life in your favorite game. The truth is that game worlds currently have tremendous visual appeal with their rich and strikingly detailed appearance; but the technology of motion, though sophisticated at its best, has not kept pace with the rapid advance of graphics. In war scenes, massive explosions should be followed by a destructive rain of debris and a chain reaction of damage. Nature should be as dramatic and chilling as a wall of molten lava that overcomes everything in its path, from rock and steel to flesh and bone, through forest and city to the steaming ocean shore. Characters ought to be seen in loose, flowing clothing, not just skin-tight unitards, with hair that gets swept subtly by the wind as it reacts to the motion of a virtual actor. The player’s environment should be responsive, intuitive and seamless, free of the artificial rules so frequently imposed by the limits of technology and the economy of game production, rules that prompt disbelief. How do we get there from here? How do we bring the motion and forces of nature into the game, deep enough to truly complement the amazing graphics quality we’ve come to enjoy? Game developers took the first steps along this path by implementing just enough physics to control how game characters move, collide, and react when they interact with ach other, with the player and with environmental forces. Dynamics has been at the core of game technology since Pong™. But to satisfy these yet-unrealized consumer expectations we must push beyond Newtonian physics into a pervasive, interactive hyper-reality of incredible explosions, gelatinous creatures oozing acidic slime, walls of molten lava, windswept hair, and clothing so fine it makes a designer jealous. Consumer expectations for immersive, interactive gaming demand a new class of processor: the Physics Processing Unit (PPU), which has been created to meet this demand. The PPU enhances the game experience by meeting the need for extreme movement and interaction. The PPU accelerates physics-related calculations in computer-based games. Its unprecedented power to perform advanced real-time physics simulation enables deeper player-environment interaction and immersive, living detail. With the PPU, car fenders will at last crumple with satisfying detail as the gamer slides his car head-on into a wall, thick with clouds of dust, curls of smoke and shards of glass one expects from being so close to the action. The PPU provides a more lifelike gaming experience. The advent of PPUs and the anticipated transformation of games mirror the story of 3D Graphics Processing Units (GPUs) in the 1990s. These 3D GPUs abstracted the rendering and display functions which were until then performed in software, applying purpose built architectures to speed up and enhance those functions. As a result, the visual quality of games increased dramatically, and soon after their introduction every significant game was compelled to incorporate the new 3D hardware technology, much to the happy benefit of gaming. The adoption of 3D GPUs reduced the CPU rendering load in most games, but interestingly, as graphics content expanded in scale and scope, the requirements on the CPU for preparation, housekeeping and other tasks increased. A similar phenomenon can be anticipated with the adoption of PPUs. The increased depth and quality of physically interactive environments will expand the requirements for AI, game logic and even rendering. In short, the CPU “thinks and AGEIA Technologies Inc. 82 Pioneer Way. Mountain View, California. 94041 Physics, Gameplay and the Physics Processing Unit 2 orchestrates,” the GPU “renders and displays,” and the PPU “moves and interacts,” and all complement each other as a platform for spectacular gameplay. The Future of Gaming is Physics What is physics content? It’s everything about how things move, how they behave, and how they interact. It’s how things happen: without scripting, and without expensive micromanagement by programmers or artists. It’s about control: giving procedural, mathematical control over the environment to the game designer and level designer, so that gameplay and immersive feel are brought about naturally by the objects in a game. Below we describe a few elements of physical design and where they can be found in a game. Material Properties are physical characteristics like density, friction and bounciness. Designers can create slippery surfaces that are difficult to walk on; wooden objects that bend slightly and then crack; rubber surfaces that bounce; metal surfaces that resist bending but become dented with extreme force; and stones that shatter when smashed under great pressure. Rigid Body Dynamics and Collision Detection are "I agree with Darren on the simulation technologies that provide believable physics - absolutely incredible! Newtonian motion to game objects. With Renderware, Havok, Epic, Valve and others all competing in A player’s belief in the game environment erodes the creation of kinematic when objects pass through each other. engines, I think physics is the new graphics." Going beyond gross motion, good rigid body technology allows the game developer to create very natural collisions and couple them to -- Christian Allebest, Editor- secondary effects, like the chinking noise when Video Games, Tom ’s Hardware coins hit the floor, or skid marks where the driver www.tomshardware.com hit the brakes. Many games today deploy rigid body dynamics as a core design element, but scaling this technique on today’s platforms is very challenging due to the aggressive processing demands of the technology. Joints and Springs are tools for modeling complex mechanisms, going beyond stacks of crates and into the realm of vehicles, character movement, doors and levers, and the ability for the player to pick up and manipulate objects in the world. Fluids– beyond the simple undulating waves of surface fluids, real volumetric fluids can enhance the visual appeal of many scenes, from barrels of oil, to water towers, to fire hoses and fluid weapons. Real fluids interact naturally with dynamic bodies, pushing them around the world and flowing around them. Smart Particle Systems like fire, smoke and fog can be “aware” of other aspects of the environment and interact realistically with them, like smoke contained in a room. Real smoke rises to the ceiling and collects there, filling the room from the top down, until ultimately spilling out of the windows and drifting on the air currents. Smart particles make this possible. Cloth – high-fidelity clothing means flowing robes, skirts and cloaks that look good and can contribute to gameplay as well. Imagine your character is attacked by an unknown assailant in a dark alley, and later the culprit is revealed when an item lost in the robbery is spied beneath a robe! AGEIA Technologies Inc. 82 Pioneer Way. Mountain View, California. 94041 Physics, Gameplay and the Physics Processing Unit 3 The Future of Physics is Hardware Since the dawn of computer-based gaming, designers and players have argued over what makes a game playable. Perhaps the only consistent point of agreement is frame rate. Simply stated, irrespective of genre, if a game can’t be played at upwards of 30 frames per second, few gamers will play it. For this reason, game developers have been loath to include design elements that slow the frame rate beneath these levels. The same was once true for 3D graphics. In the early nineties, few games used 3D graphics because software 3D rendering slowed the game unacceptably. Then 3D graphics accelerators became popular in the mid 1990s, which offloaded 3D rendering from the CPU. Soon thereafter, 3D capable graphics processors (GPUs) became standard on even entry-level computers, and 3D graphics and high- resolution textures became standard elements of virtually all games. A parallel dynamic exists today relating to physics. Computer and console CPUs are responsible for all "We're still doing basically trivial non-graphics-related game play tasks like game things…in future game logic, scoring and artificial intelligence, as well as generations there will be physics. In fact, it’s estimated that during game simulations of weather, play, only about one-sixth of a fully utilized CPU is simulations of liquids, typically dedicated to physics, and actual simulations of dust motes going experience shows that this is clearly insufficient to through the air and transferring provide the environmental quality that gamers are through the environment." coming to expect. When multicore CPUs are deployed, where one -- John Carmack , GDC 2004 processor can be dedicated to physics, physics Keynote Address performance will be better than when using a single processor; however, there are many classes of physics simulation that still cannot be done in real time.