In the real
world, even man-made objects usually have much different details
on their sides than on their bottoms instead of a single texture
wrapped around all sides. Of course, transitions and details are
generally non-tileable, which means that if your entire cliff (or
building wall) is one very tall face, you will either be limited
in the amount of texture detail you can use (because you won't be
able to tile it up the cliff or wall), or you'll have to forget
about the transition altogether. Depending on the engine, the best
solution to this is to build special geometry to accommodate non-tileable
transition textures, or to use a decal/texture-layering system if
one is available.
Finally, even in large
areas without transitions, such as a field of grass or a large rock
face, it is very important to have specific and non-repeating details.
Again, it is important that the entire area not be one single face
from a texturing standpoint, or else it will be impossible to put
these details down. The erroneous solution in games of old to avoiding
the repetitious look across large tiled faces has been to try to
paint more interesting detail into the tiled texture. Unfortunately,
our eyes are incredibly sensitive to patterns, and as soon as a
texture which looks very natural and interesting on its own is textured
across a large area, it will form into a big repeating pattern.
This is very evident with many of the rock textures in Unreal
- they were evidently ripped from photographs, always a dangerous
way to start an outdoor texture because of the non-repeating nature
of the real world. These photo-manipulated rock textures mostly
include a couple very distinctive dark shadows, and they look like
very nice pieces of rock in the texture browser, but become a series
of dark swirls in the world.
A better approach to
realistic textures is to start with a very plain base which tiles
with little visible repetition, and then to create "highlight"
pieces. These highlight pieces can be little more than the same
base texture with a single detail added, such as a cluster of rocks
in a field of grass. The important thing is not to tile this detail
endlessly - instead, it should be placed on a face where the texture
doesn't tile much, if at all. As the player runs by, what they should
see is a large field of grass broken up by a single clump of rocks,
rather than a large field of plain grass, then a large field of
grass with a clump of rocks repeating every few feet, then maybe
a large field of grass with the same pattern of little flowers.
In any engine which allows decals or layering, the details can be
placed without regard to the base texture - so long, of course,
as they are placed where it makes sense. Positioning that clump
of rocks detail so that it wraps halfway up a steep cliff should
be an obvious no-no, but it happens more than I would expect.
This is a good place
to end this column - lighting and texture variation is a large subject,
and it can be practiced no matter what the underlying geometry of
the level is. What I thought was going to be a simple discussion
of some ideas about building levels gained from my now-cancelled
project is actually shaping up to be a fairly major dissertation,
so next time I'll continue and talk about realistic outdoor geometry.
It is also necessary to address the vagaries of game design in outdoor
areas, but that may not even be possible in the next column. Until
then, keep the initial point in mind - making pleasing outdoor areas
requires far more effort than a simple set of gray corridors, but
it is becoming more necessary every day, unless you want to be stuck
playing in and making corridors for the rest of your life.
Beaker Wyckoff is a game designer, not a level designer,