154
Video Game Design Foundations
The
poly count
is the
number of polygons used to
make a 3D object. This number
is a critical measurement. The
more polys, the more lifelike the
object becomes, as illustrated in
Figure 4-37. So, why not make
all objects with a high poly
count? Simple; every polygon
needs to be morphed as the
object is moved. The computer
needs to calculate the change in
distance between each vertex of
the polygon as the object gets
bigger, smaller, and moves to a
different view. If every object
has a high poly count, it would
take an enormous amount of
time for the computer to render
the objects as they move. Some
processors would not be able to
keep up with the calculations. On
these systems, the view may skip,
play slowly, or appear to have
glitches.
Look at the example of an
expanding-ball toy. Imagine how
long it would take to calculate the
change in distance between every
vertex each time the ball changes
shape. The computer must do
just that. The more polygons, the
more vertices and the harder the
task.
The color and texture maps
assigned to an object
tessellate
around the object. Each poly
has a piece of the texture image
on its surface, like a
mosaic.
See Figure 4-38. The amount of
tessellation is controlled by the
number of polys on the object.
The higher the poly count, the
greater the tessellation. Therefore,
the higher the poly count, the
smaller each slice of the color or
texture map.
CHEAT CODE: MOSAIC
A mosaic is a design created by
placing colored tiles, stones, or
glass in a pattern to make a picture.
This relates to 3D models because
the model uses colored polygons to create an image just
like the mosaic picture.
Figure 4-38.
Notice how these tiles
fit together to make the
image. If you think of
each tile in the mosaic
as a polygon, you
can see how a texture
would be mapped
to the polys on a 3D
game object.
Shutterstock.com
Figure 4-37.
Goodheart-Willcox Publisher
As the polygon count increases, the
smoothness of round surfaces increases.
However, it also takes longer for the
computer to render. Here, the sphere on
the right looks the most realistic. For a
game, however, maybe the middle sphere
is used because it still looks like a sphere,
but has fewer polygons.