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2004 GDC Proceedings
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Building a Million Particle System
Abstract: Current implementations of particle systems can handle up to 10,000 particles in real-time situations and are mostly limited by transfers of particle data from the main processor to the graphics hardware (GPU) for rendering. A full GPU implementation however does not have this bottleneck and can simulate and render one million particles in real-time on recent hardware. This allows a dramatic increase in the level of detail and also much smaller particles. Thus it goes back again towards the original idea of a particle being a minimal geometry element. The massively parallel simulation of particle physics on a GPU can be a flexible combination of a multitude of motion and position operations, such as gravity, local forces, and collision with primitive geometry shapes or texture-based height fields. This high level of realism allows particle systems to be used as gameplay element, such as for fog-like local invisibility. Additionally this technique can be combined with a parallel sorting algorithm, performing a distance- based sorting of the particles for correct alpha-blended rendering.
High Dynamic Range Lighting
Abstract: This session shows how to create more realistic environments and lighting through high dynamic imagery and image-based lighting. The course presents how high dynamic range imagery (HDRI) covering the full range of light in the real world can as texture maps in real-time virtual environments and as realistic sources of illumination for CG objects and characters. The course explains the relationship between HDRI, Image-Based Lighting, and Global Illumination, and how the three can be used together to create renderings and composites with extremely high realism. Examples are given using renderings from LightWave 3D, Maya, RADIANCE, and the Arnold rendering system. HDRI file formats, manipulation software, special blur and glare effects, and issues surrounding gamma correction are presented.
Light Scattering: Oh, that Looks Cool! Can we Have it in the Game, Real Quick?
Abstract: Lately a lot of exciting new and old techniques to enhance lighting used in games have become technically feasible on current generation graphics hardware. Surprisingly, or perhaps not so surprisingly – a large number of these techniques have so far not made it into real game applications in any larger way shape or form, sometimes not at all. This talk illustrates the problems encountered and solutions found when trying to go from technology demonstration to real game application using Factor 5’s latest game ‘Star Wars: Rebel Strike’ and the light scattering technique used in it as an example. Related technology used in the game are covered.
Adding Spherical Harmonic Lighting to the Sushi Engine
Abstract: Spherical Harmonic (SH) based lighting solution have entered the mainstream of real-time graphics. This relatively new lighting technique offers many advantages to engine programmers in both performance and advanced lighting realism. The internal engine and shader library that ATI’s demo team uses for their cutting edge technology demos are the case study on how to add support for SH lighting to a real-time graphics environment. This session discusses artist usability, the preprocess tool chain, and runtime issues and solutions they have encountered while adding SH lighting support to their tools, shader library, and engine.
Advanced Real-Time Reflectance
Abstract: Recent advances in graphics hardware and APIs are enabling game developers to use increasingly general reflectance models in their games. However, physics and computer graphics research has generated a large body of knowledge about material reflectance which has not yet been leveraged by game developers. This talk starts with the basic physics of reflectance, and continues to explain the deficiencies of the most commonly-used model (Blinn-Phong). The presentation covers various reflectance models used in the computer graphics literature (such as Cook- Torrance, Ashikhmin-Shirley, Ward, LaFortune and others). Practical implementation methods for these reflectance models on modern programmable hardware are used to realistically render several real-world materials. The presentation concludes by discussing the integratation of these models into the game development pipeline.
Deferred Shading on DX9 Class Hardware and the Xbox
Abstract: Deferred Shading is a rendering technique where all lighting/shading computations are delayed until after the scene is rendered. This technique is used in the non-realtime and raytracing world but only recently has become practical for realtime gaming on the PC and console. For the game developer this means a complete decoupling of geometry rendering from lighting, and removing the problem of determining which geometry interacts with which lights. This also eliminates traditional hardware limitations on the number and types of lights used. A deferred shading engine is capable of taking advantage of the latest hardware and delivering all the cutting edge shading effects you want: 100% per-pixel lighting, extensive material property functions (NDFs, BRDFs), true High Dynamic Range lighting, Volumetric and true 3D shaped lights. The presenters, who have developed and shipped titles using deferred shading, will take the attendees from the high level concepts to the nuts and bolts of developing a deferred shading renderer.
Destruction on a Diet
Abstract: This presentation follows the evolution of techniques for environmental interactivity successfully used in Twisted Metal: Black, War of the Monsters, and Downhill Domination. The lecture covers efficient methods for destruction and secondary AI, with a description of the entire process from asset creation, through the tool chain, and into the implantation of the run-time behaviors. Also discussed are the implications of a changing topology with dynamic elements on AI and network play.
Fast Yet Realistic Deformation and Fracture
Abstract: This talk discusses the details of a simple to implement finite element method for modeling deformable solids. Although the mathematical underpinnings of continuum mechanics cannot be ignored, the main concern of the talk focuses on how one goes about implementing and using the techniques to generate interesting behaviors. In addition to basic elastic deformation, more advance techniques for plastic deformation and fracture are also covered.
Motion Capture-driven Simulation for Characters
Abstract: Simulation game engines (e.g. Havoc and Karma) are becoming increasingly popular, but the question of controlling characters in their frameworks is still mostly unanswered. Subtlies in the motion of animated, humanlike characters affect the believability, aesthetic and impact of animated agents in video games. While motion capture produces characters with stylistic detail in their movements, the data is difficult to edit and control, especially in a changing environment like those seen in the rich virtual worlds of current games. Dynamic simulation allows physical laws to dictate interactions under such circumstances, but controllers for simulated agents are difficult to construct because we do not know how to specify the details of human motion procedurally. In this lecture, we describe a technique for dynamic simulation driven by motion capture data as a means of controlling dynamic characters beyond the simple motion blending techniqes used thus far. Through combining simulation and motion capture, we work to retain the interactivity, reactivity, and non-precscribed effects of dynamics with the styliezed details of motion capture data.
Motion Synthesis
Abstract: Realistic character animation is a crucial component of a successful game. Because the players interact with the synthetic characters, their motions must react to a variety of situations. Capturing or key-framing all possible motions that a game character may need to perform is impractical. The presenter shows two motion synthesis algorithms that can generate motions on the fly for a variety of user or game engine constraints by re-arranging frames from a collection of previously captured or animated motions.
Practical Implementation of High Dynamic Range Rendering
Abstract: For game real-time graphics, the visual expression attractiveness is more important than rendering accuracy. It is difficult to create attractive images just from more precise calculation. It is important to understand the differences between HDR and LDR and which is appropriate according to the type of expressions. This lecture should help clarify some of the problems when equipping HDR, introduce some techniques of HDR expressions that are possible to use on present hardware, DX8 and DX9, and indicate the expressions that can be advanced from HDR.
Practical Shadows: Out of the Demo and Into the Engine
Abstract: There are many shadowing algorithms available, such as blob shadows, shadow maps of various types, projective shadow maps, and stencil volume shadows. But they all have limitations, some of them work on some platforms and not others, each is appropriate for different situations. This lecture introduces each method and briefly discusses their major features and limitations. It then explores how to mix and match the various methods in a practical large-world engine on real console hardware. The lecture is mainly about the tricks and tips, where corners can be cut, when to use each technique, and the efficiency and scalability of each. The emphasis is using these methods in a practical game with large, complex and unconstrained scenes, rather than simply writing a technology demo.
Procedural Shaders: A Feature Animation Perspective
Abstract: Procedural shaders are textures generated from a small number of parameters. This talk compares the procedural shaders used in feature animation such as the Perlin Noise function, brick and fur shaders, and their real-time counterparts, explaining the tradeoffs required to bring them to real time.
Real-Time Global Illumination
Abstract: The session explores how real-time global illumination game engines can be create on current hardware. A brief history on various global illumination techniques is given and then the presenter explores how they can be adopted in to real-time 3D engines. He also discusses brand new approaches targeted directly at the real-time field.
Reusing Shading for Interactive Global Illumination
Abstract: This session presents recent techniques that reuse shading information to bridge the gap between slow shading and fast interactive image update. The common approach in all these systems is that shading is sparsely sampled and reconstructed for interactive rendering. This session covers several recent techniques including image-based techniques, mesh-based approaches, and four-dimensional approaches. This session also reviews key concepts in global illumination, and describe the state of the art in fast ray tracing. The techniques that are discussed include frameless rendering, image warping, the render cache and edge- and-point rendering, shading cache and corrective texturing, and four dimensional approaches such as 4D radiance interpolants and holodeck. Fast ray tracers such as GPU-based and CPU-accelerated approaches are also discussed.
The Full Spectrum Warrior Camera System
Abstract: This lecture focuses on the details of the camera system technology used in the game Full Spectrum Warrior (FSW). The lecture covers the camera motion system, which is based on a modified version of the proportional controller often used in game camera systems. The lecture also covers the unique "autolook" feature that gives players a better view of the battlefield in situations where the view would normally be largely obstructed. Collision avoidance and high-level architecture considerations are also discussed, as well as techniques for providing feedback to programmers and designers, who need to "tune" the system for optimal performance. The lecture concludes with a discussion of the limitations of the FSW camera system, a summary of recommended practices, and ideas for future investigation.
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