108 Video Game Design Foundations
a character that works. The character will need to be designed so it can be
seen from all of these different angles. Most game designers create these
simulated 3D characters with a minimum of 26 viewing angles for each pose.
Highly defi ned characters may have more than 100 viewing angles for each
pose.
In some 2.5D games, the character set is replaced with actual 3D
models with full articulation. Full articulation means all of a character’s
body parts can move through a range of motion in a realistic manner. In
these games, the background is still fl at and two dimensional, but the charac-
ters and interactive objects are true 3D models.
Three-Dimensional Games
Three-dimensional (3D) games have 3D characters and 3D
background objects called models. Recall from Chapter 1 that models are
different from sprites. Sprites are defi ned in two dimensions (X and Y).
Models are defi ned in three dimensions (X, Y, and Z), Figure 4-19. They are
computer generated in real time to show the correct angle and pose. It takes
a lot of computer processing to make a 3D model move.
The discussions in the following sections are actually oversimplifi ed
explanations of how perspective, pixel shading, vertices, scaling, and depth
work within a game. However, these discussions should give you a good idea
of these concepts that are used to make a 3D scene in a game.
3D obstacle
3D avatar
Gameplay is
in a 2D frame
even though
the graphics
appear 3D
Figure 4-18. This is a 2.5D game. The game frame is two dimensional, but the characters and obstacles are three
dimensional.