Journal of Game Development

Volume 1 - Issue 3

ABSTRACT 1

EFFICIENT TESSELLATION ON THE GPU THROUGH INSTANCING
Holger Gruen
Krauss-Maffei Wegmann & Co. KG
Bavaria, Germany

This article describes how instancing techniques can be used to refine objects on the vertex units of the GPU. The methods described can efficiently tessellate and evaluate surface patches and can even be used to achieve surface compression.

To realize efficient tessellation, you can instance a pre-tessellated flat triangle many times. The vertices of this triangle describe positions as barycentric coordinates only. These barycentric coordinates are basically blending factors that you can use to blend three corners of a triangle to generate a point inside this triangle.

To refine an object, you draw one instance of the pre-tessellated triangle for each triangle of the object (see the following picture). As input for every instance, the position of the vertices and other relevant attributes of the original object triangles are provided. Inside a vertex program the barycentric coordinates along with the object/triangle data are used to compute vertices on the refined object. The potential uses for such on-the-fly refinements are manifold.

If the object triangle data is augmented by additional data that describe control points for a higher order surface patch, the vertex program can evaluate the patch given the barycentric coordinates. An example is provided that shows how to evaluate N-Patches over objects using just one draw call.

Normal mapping tools (for example, NVIDIA® Melody™) can generate a texture that encodes normal and even the height of a high polygon model over a low polygon model. Using such a texture as a vertex texture, real-time refinement is used to displace a vertex of a refined model along the surface normal using the height. This technique can theoretically achieve a 1:12 size compression/decompression of vertex data for high poly objects. It is a technology especially relevant for game consoles that need smaller memory footprints. Current limitations on vertex texture formats make it hard to achieve this ideal, however.however.

ABSTRACT 2

A GENERIC APPROACH FOR OBTAINING HIGHER ENTERTAINMENT IN PREDATOR/PREY GAMES
Georgios N. Yannakakis and John Hallam
Maersk Institute for Production Quality
University of Southern Denmark

ABSTRACT

This article constitutes a sequel to our previous work focused on investigating cooperative behaviors, adaptive learning and online interaction toward the generation of entertainment in computer games. A humanverified metric of interest (i.e., player entertainment) of predator/prey games and a neuro-evolution online learning (i.e., during play) approach are used to serve this purpose. Experiments presented here demonstrate the generality of the proposed approach, in its ability to overcome the difficulties of learning in real-time and generate interesting predator/prey games, over game type, complexity, topology, initial opponent behavior, and player type.

ABSTRACT 3

BRINGING GAME CHARACTERS TO LIFE
Stephen Crane
Executive Vice President and Chief Creative Officer,
Midway Home Entertainment

ABSTRACT

About 10 years ago, I met a senior Disney animator at a party. She was responsible for designing one of the principal characters in The Lion King, which had been released several weeks earlier and was still tearing up the box office charts. She was in an understandably expansive mood . . . at least until I mentioned that I was in the 3D computer graphics business. Her eyes narrowed, and she stepped closer to me, practically poking me in the chest with her finger: “You’ll never create a character with a computer,” she said darkly and walked away.

I didn’t argue the point at the time, but about a year later, Toy Story was released– the first 3D animated feature–which, of course, was chock-full of memorable characters. In the years that followed, 3D characters have become an orthodox part of filmmaking. It’s gotten to the point where 3D computer-generated actors are used interchangeably with real ones, notably in the recent Star Wars movies and the Lord of the Rings trilogy.

I’m not sure what the woman I met at the party is up to these days; I suspect she would have to concede the point on 3D characters in film. But if she issued a similar challenge about computer-generated characters in games, her contention would be harder to refute.