[1] Formerly, a popular method of simulating a character's movement involved storing a variety of motions and choosing the most appropriate one during run-time.
[2] The simulated figure that is manipulated to show the motion is represented as a hierarchical connection of rigid links by joints.
This representation is sufficient, because knowing only the degrees for each joint and the root, the figure can be rendered at any time.
A happy walking motion may be characterized by a simulated figure's posture being upright and its gait being energetic and fast-paced.
This means that their times must be made generic so that significant structural events occur simultaneously.
[1] Inverse kinematics can be used with real-time motion interpolation to create interactions with a virtual environment.
For example, during a forward point contact in a walk cycle, kinematic constraints should be enabled so that the foot of the simulated figure is flush with the floor of the virtual environment.