Game Development Reference
In-Depth Information
Another problem is avoiding overdraw. If your game is in a complex interior envi-
ronment or deep in the concrete canyons of New York City, you
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ll achieve the fastest
frame rate if you only draw the polygons that you can see. Again the naive approach
is to simply draw all of the polygons in the view frustum, omitting any that are facing
away from the camera. This solution will most likely result in a disastrous frame rate
in certain areas but not others, even if the camera is pointed straight at an interior
wall. When the game is bogging down like this, it is drawing an enormous number of
polygons behind the wall, only to be covered up by the bigger polygons close to the
camera. What a waste!
You
ll need some advanced tools to help you analyze your level and calculate what
areas can be seen given a particular viewing location. Umbra Software (
www.umbra-
software.com)
has developed sophisticated PVS (potentially visible set) and portal
technologies to do this either offline or on the fly, but many games can use a simple
portal or occlusion culling technique. Competitive games are all pushing the envelope
for the illusion of extremely complicated worlds. The trick is to create these worlds so
that your environments behave well with whatever culling technique is best for your
renderer. Add to that mix of technology some nice levels of detail, and you can get a
game that looks good when objects are close up or far away.
Since 3D engines are only capable of drawing so much scenery per frame, an amaz-
ing amount of effort must go into creating the right level of design. Any environment
that is too dense must be fixed, or the frame rate will suffer along with your reviews.
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Your Artists Need to Know What Your Engine Can Do
The most common mistake made on 3D games is not communicating with
the artists about what the graphics engine can and can
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t do. Remember that
the world environment is just a backdrop, and you
ll still need to add
interactive objects, characters, special effects, and a little bit of user
interface before you can call it a day. All these things, especially the
characters, will drag your performance into the ground if the background
art is too aggressive. Try to establish CPU budgets for drawing the
background, objects, characters, and special effects early on and hold your
environment artists and level designers to it like glue. Measure the CPU time
spent preparing and rendering these objects and display it for all to see.
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Audio is one of my favorite areas of game development, and I
ve been lucky enough to
work with some of the best audio engineers and composers in the business. Game
audio can generally be split up into three major areas: sound effects, music, and speech.
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