Researchers have developed computer game characters that can react to virtual environments, and use artificial intelligence to learn how to produce their own body motion.

The animation technique, called Active Character Technology, works by adopting a process of artificial evolution so that a character learns how to move.

Based on prize winning work carried out largely at Oxford University, researchers at NaturalMotion have developed a new way of animating virtual characters in games and films.

NaturalMotion chief Torsten Reil said that computer games will now have the potential to feature truly interactive characters. "If [a character] is walking over a swaying bridge, it would react to the swaying," he said.

In traditional computer animation, all characters' moves have to be animated beforehand in a long and painstaking process.

But the NaturalMotion system simulates the body and has a 'brain' which reacts to its environment. So a character will always react differently, making this approach a huge advance.

Ironically, the researchers do not fully understand why their process works. "We let evolution do the job and looked at it afterwards. We don't know why it works, but it works," admitted Reil.

The company explained that the technique will allow animators to create lifelike characters quickly and cheaply.

NaturalMotion is talking to major games developers about incorporating the technology into future video games.