Computer game characters in the future could be truly interactive, reacting to your movements and changes in the virtual environment.

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

They have created computer characters that use artificial intelligence to learn how to produce their own body motion.

"The potential for this is truly interactive characters in computer games," said NaturalMotion Chief Executive, Torsten Reil.

"So, if it was walking over a swaying bridge, the character would react to the swaying."

Different reactions

In traditional computer animation, all a characters moves have to be animated beforehand.

This is often a long and painstaking process and means that a character can only react in a set of pre-determined ways.

The character 'learns' how to move

"Everything you see in a computer game, such as Lara Croft falling, is pre-animated," Mr Reil told the BBC programme Go Digital.

"We completely physically simulate the body. It has a brain to react to things. So, it will always react differently, which makes this approach very different to what goes on now."

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

"We put a simplified model of the brain into the character," explained Mr Torsten. "We connect this brain to the virtual muscles and then tell it how to walk."

Interest from gamers

Early characters were not very stable and tended to stumble a lot. But later generations of the character seemed to have learnt how to walk without falling over.

The researchers admit they do not fully understand why their process works.

"We let evolution do the job and look at it afterwards. We don't know why it works, but it works," Mr Reil said.

NaturalMotion believes its technique could revolutionise the film industry, allowing animators to create lifelike characters far more quickly and cheaply than at the moment.

The firm is also talking to major games developers about incorporating the technology into future video games.

NaturalMotion will be showing off its Active Character Technology at the world's leading showcase for computer graphics and interactive techniques, Siggraph, in Texas in July.