Another technology that is gaining favor with developers is skeletal animation. In its most simplistic form, models are defined by a series of bones to which a mesh skin is attached. When a series of bones is moved, its vertices are rearranged according to a weighted value (via CPU calculations). Animation is achieved fundamentally by moving the skeleton; skin is generated mathematically.

Using skeletal animation not only simplifies the animation process, but it also requires far less memory - a commodity nowadays with new quality features consuming precious bandwidth.

Curious as to the developer support behind skeletal animation, we turned to Tim Sweeny, programmer behind Unreal Tournament.

"Skeletal animation is great. 60%+ of the polys in our next-gen scenes will be from skeletal animated models, the remainder static geometry."

Unfortunately, this form of animation has a weakness in the way it handles joints. When a transform causes a joint to bend, a gap may be created which causes the model to look very unnatural. This weakness is overcome using a technique called skinning. In skinning, the positions of the vertices are adjusted to create a continuous flexible joint, restoring realism.