is based on the idea that an animated object has a beginning state that changes
over time, reaching a final state.
state may include position, shape, colour, or other properties.
keyframing, the animator only specifies the “key” frames, and the intermediate
frames between the start and end states are found through interpolation.
traditional animation, often keyframes were specified by a senior artist and
the tweened frames were created manually by less experienced (and lower paid)
artists; today it is typically done using interpolation on a computer.
MD2 file rendered using keyframe
interpolation on YouTube