“Living in a Stressful World: Real-time Stress Calculation”

Lecture by Eric Arnold at GDC 2011.

With the rise of destruction and environmental interaction in games, the need to simulate stress is becoming more apparent.  Without the ability to tower should topple you are limited to superficial damage to the surface, or full scale canned animation of the building failing.  As players become more sophisticated they expect finer grained interaction with their environment.  In order to provide that, we need a way to simulate both internal and external forces on the object in real-time.

Through Red Faction: Guerrilla and Red Faction: Armageddon we have developed a fast, flexible system to simulate stress on an object.  The speed is derived from spreading the processing over multiple frames.  Not only does this allow us to tightly control the processing time per frame devoted to stress calculations, but it also gives a realistic pause between damage and structural failure and allows us to warn the player before the building collapses in on them.  The flexibility comes from being based on a set of simple rules.  These rules allow us to handle a five story building the same as a five foot wall.

Even with all the technology behind it, where the system really shines is ease of interaction.  Designers and artists barely have to know that it exists when done right.  Freeing them of complex setup procedures allows them to concentrate on aesthetic and game play issues.  In the end, technology is judged by what is created with it, not what could be created, so the easier it is to work with the more spectacular the results will be.

This session will cover all aspects that went in to creating a full featured stress simulation that balances the needs of programming and design.