Last June, a part of the Fishing Cactus crew attended to the Game AI conference which took place in Paris, and I am glad that I was part of it. This conference gather peoples with the same passions video game and AI.

We had some really interesting talks, especially about the animation driven by the AI. For instance we could see the parametric animation system developed in the “CRY Engine”. When I saw this, the first day of the conference, I was impressed, seeing locomotion animations moving around by blending a couple of animations together to get a realistic behavior. The graphical animator do not have to depict all the animations required for a character to run, while turning and climbing hills.

But the next day, when came the turn of Simon Mack to speak about the “Euphoria Engine” of Natural Motion, I was literally stunned.

Euphoria is an engine used for animating 3D characters in a way that the gestures look very natural and coming from a real person. Unlike the classic key frame animation, which involves a static animation, this system allows each character to play the animation in a unique way.

The engine is based on Dynamic Motion Synthesis, which is a technique that generates the motion of the character by applying different constraints on it (like for the ragdolls). Euphoria uses a complex biomechanical model, simulating the skeleton, its joints, and the muscles. To drive the skeleton, the engine uses neural networks as controllers to determine the forces to apply. And to make it more intelligent, the controllers are chosen by some genetic algorithms which pick the fittest controller over multiple generations and trials. But it also allows the animator to give some expressive behavior to the character, like preservation of itself, or keeping its balance while knocked by others.

So in order to build a new character in your game with Euphoria, you first need to create a new controller for it. For this, you will have to tweak the parameters of the neural network controlling the body. Then you will need to tweak the fitness function of the genetic algorithm in order to take into account your new controller. Then the animator will have to give a behavior to your character which fits the best in your game.

Have a look on the amazing result you can get from this piece of technology:
Euphoria – Natural Motion

Rockstar uses Euphoria in its game GTA IV, to control the pedestrians. We can see them trying to dodge a car which is about to hit them, or protecting their head while falling on the ground if the car managed to hit its target. And more recently, the game BackBreaker also uses it, to give natural animations to the players, when they hit each other’s by blocking the legs for example.

By combining, AI with physics and biomechanics, Euphoria brings some really interesting possibilities to the game and movie industry.