Ultimate Game Design : Building game worlds

C H A P T E R 3
use to detail your scene or level. You should give considerable forethought to creating
your texture set. You’ll want to build the right texture pieces in the right ways to
accomplish your visual goals. For example, your 128×128 textures might look great
on floors and walls, but if you attempt to use them in another way, you may run into
trouble and need to resize them or even create custom versions.
As previously stated, textures are placed onto a surface using a U, V coordinate
system to locate a map on a mesh or geometry surface. When you stamp textures on a
surface, though, they may not line up correctly. You will want to “shift” or “slide”
them across the surface to line them up correctly. Most game engine tools allow you
to accomplish this by changing the U, V values for the selected texture. This is very
helpful in lining up textures in the way that you would like.
In some cases, you might want to actually change the draw scale or draw size of a
certain texture to make it fit the scene better (in other words, at the correct scale relative
to everything else in the scene). You can do this by changing the U, V draw values,
which will stretch or shrink your texture in those directions according to your
changes. Be careful when doing this, because you may get unintended results. You
can only stretch or shrink textures so far, before it becomes totally obvious that you
have done so. It will blur out or compress your textures to the point that they cannot
be used. Again, this is why, at creation, you need to know how you intend to use your
textures.
P ARTICLES
Some of the most interesting, complex, and processor-intensive visual effects being
created for games (and movies) are using particle systems or dynamics. When you
think of particle systems, think of naturally occurring behaviors, such as the flocking
of birds as they fly together, forming a larger single unit out of many individuals, or
localized rainfall dropping from a single cloud onto a scarecrow. In a flock of birds
flying together, each bird becomes a particle in the system. In a simulated rainfall
from a single cloud, each drop of rain becomes a particle in the system.
Here are some other effects you can build with particles:
� Fire from a torch
� Exhaust from vehicle tailpipes
� An attack formation of angry mutants
� Swarms or clusters of objects
� Sports dynamics (skater’s ice chips, shattering baseball bats, dirt clouds from
slides, divots from bad golf swings, and so on)
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Lighting, Texturing, Particles, Effects, and Audio