Journal of Game Development

Volume 1 - Issue 2

ABSTRACT 1

Oblique View Frustum Depth Projection and Clipping
Eric Lengyel
Terathon Software
Santa Monica, CA 90404
lengyel@terathon.com

ABSTRACT

Several 3D rendering techniques have been developed in which part of the final image is the result of rendering from a virtual camera whose position in the scene differs from that of the primary camera. In these situations, there is usually a planar surface, such as the reflecting plane of a mirror, that can be considered the physical boundary of the recursively rendered image. In order to avoid artifacts that can arise when rendered geometry penetrates the boundary plane from the perspective of the virtual camera, an additional clipping plane must be added to the standard six-sided view frustum. However, many 3D graphics processors cannot support an extra clipping plane natively, or require that vertex and fragment shaders be augmented to explicitly perform the additional clipping operation.

This article discusses a technique that modifies the projection matrix in such a way that the conventional near plane of the view frustum is repositioned to serve as the generally oblique boundary clipping plane. Doing so avoids the performance penalty and burden of developing multiple shaders associated with user-defined clipping planes by keeping the total number of clipping planes at six. The near plane is moved without affecting the four side planes, but the conventional far plane is inescapably destroyed. We analyze the effect on the far plane as well as the related impact on depth buffer precision and present a method for constructing the optimal oblique view frustum.

ABSTRACT 2

Intelligent Lighting for Game Environments
Magy Seif El-Nasr
School of Information Science and Technology
Pennsylvania State University
magy@ist.psu.edu

ABSTRACT
Lighting design is an important topic of game development. There are many functions that lighting assumes in game environments, including directing attention, establishing good action visibility, evoking emotions, setting atmosphere, and providing depth. Current lighting design techniques rely on static manually designed lighting, where designers set up the positions, angles, and colors for each light in a level. Game environments are dynamic and unpredictable; physical and narrative scene content, including character locations, tension, and narrative goals, change unpredictably in real time due to user interaction. Thus, current static techniques often do not adequately adapt to serve desired aesthetic and communicative functions or perceptual effects. Recently, Doom 3 incorporated dynamic real-time lighting and demonstrated many advantages of using real-time dynamic lighting in games, including heightening the emotional engagement and enhancing the overall interactive experience. However, the technique is scripted and tightly coupled to game content. In this article, we present ELE (Expressive Lighting Engine), an intelligent lighting system that automatically sets and adjusts scene lighting in real time to achieve aesthetic and communicative functions, including evoking emotions, directing visual focus, and providing visibility and depth. ELE operates as a separate system that interacts with game/graphics engines through a standard interface. In this article, we will discuss ELE and its interface with Unreal Tournament 2003. We will also present results showing ELE in action. These results show

• Utility of real-time adaptive lighting in providing visual focus, setting atmosphere, evoking emotions, and establishing visibility in interactive environments
• Acceleration in the development process due to the introduction of an automatic system for lighting that can be overridden by designers at a high level, thus eliminating the time-consuming process of setting individual light parameters for each level and scene

ABSTRACT 3

Unifying the Visions of What Games Can Be
Ben Sawyer
Digitalmill Portland, ME
bsawyer@dmill.com

ABSTRACT

My day job has been fairly varied over the years, but increasingly it involves expounding about games to people who don’t spend a lot of time playing or thinking about them. I suspect that the readers of this journal, its authors, reviewers, and editors do their increasing share of this as well. Games have become such a force over the last 10 years that more and more people are trying to figure out how games apply to them and their organizations. Those of us who believe that digital games, an emergent game culture, and derivative game technologies are special are also doing our best to talk it up outright.

In a sense, the world is trying to decide all the roles games can have, and for me that involves defining the non-entertainment applications of games—what have become known as “serious games.” As I’ve said before, “all games are serious,” and it’s because people are taking games seriously that my colleagues and I have been enabled to create The Serious Games Initiative. Serious Games is just one outgrowth of the ascendancy of games as an industrial and cultural force.

I could go on about serious games for a long time—I often do with the press to the point that they say “enough!” I’m not about to do that here because I think there is a bigger issue at stake. It’s a larger discussion, which serious games is a part of. That’s the idea of figuring out “what games can be” and helping make that happen.

I believe we are at a point where we need a unified vision of what games can be, and I think it’s not going to come from the boardrooms of the publishers, or from the rank and file of overworked game developers. It’s going to be organized by academia working in conjunction with the industry. It’s going to come from those who are free to focus on all the things games can be. It’s going to require a level of detached credibility (and capability) that is situated outside the core of the industry for it to be more readily accepted by the population at large.