691ing about within a relatively large static background area. Other games, like
the arcade classic Asteroids or the Xbox 360 retro hit Geometry Wars, have no
static elements to speak of (other than a black screen). The dynamic elements
of a game are usually more expensive than the static elements in terms of CPU
resources, so most 3D games are constrained to a limited number of dynamic
elements. However, the higher the ratio of dynamic to static elements, the
more “alive” the game world can seem to the player. As gaming hardware
becomes more and more powerful, games are achieving higher and higher
dynamic-to-static ratios.
It’s important to note that the distinction between the dynamic and static
elements in a game world is oft en a bit blurry. For example, in the arcade game
Hydro Thunder, the waterfalls were dynamic, in the sense that their textures
animated, they had dynamic mist eff ects at their bases, and they could be
placed into the game world and positioned by a game designer independently
of the terrain and water surface. However, from an engineering standpoint,
waterfalls were treated as static elements because they did not interact with
the boats in the race in any way (other than to obscure the player’s view of hid-
Figure 13.1. A typical game world is comprised of both static and dynamic elements.
13.1. Anatomy of a Game World