Procedural Animation
Animation can also be defined procedurally.
Rules are established for a system and an initial state
is defined for objects in the system.
Object locations or parameters for subsequent frames are
computed by applying the forces or behaviors defined for the system to
the conditions established in the previous frame.
Look, Ma, no keyframes!
Procedural animation can be very useful for generating
much lifelike motion from relatively little input.
But, since the look of future frames is entirely
dependent on conditions from previous frames, procedural approaches can
suffer from lack of explicit control over the look of individual frames.
Particle systems determine
multiple point locations for each frame (or time step) in a simulation
according to generation and behavior rules for the particles (initial
velocity, decay rates, lifespan, etc.), as well as forces in effect in
the system (gravity, wind, etc.)
Typically, geometry is then instanced at each particle
location to allow rendering of surfaces or atmospheric effects.
Particle systems often are used to simulate natural
phenomena like clouds, running water, fire, etc.
Physical Dynamics
approaches assign properties (mass, resilience, etc.) to objects in
the scene, establish a dynamics environment (gravity, density of the
``air'', collision detection relationships, etc.), and determine an
initial state for the simulation.
As with particle systems, each successive frame of the
simulation is determined by applying these rules to the conditions that
existed in the previous frame(s).
You could also pre-compute motion dynamics by running a
numerical simulation and loading the resulting motion data into
appropriate animation channels for the objects in question.
This file was last modified on September 18, 2000.