685hair move as if it were a rope or deformable body. This is an active area
of research, and the quality of hair in games continues to improve.
z Water surface simulations and buoyancy. Games have been doing water
surface simulations and buoyancy for some time now. This can be done
via a special-case system (not part of the physics engine per se), or it can
be modeled via forces within the physics simulation. Organic move-
ment of the water surface is oft en a rendering eff ect only and does not
aff ect the physics simulation at all. From the point of view of physics,
the water surface is oft en modeled as a plane. For large displacements
in the water surface, the entire plane might be moved. However, some
game teams and researchers are pushing the limits of these simulations,
allowing for dynamic water surfaces, waves that crest, realistic current
simulations, and more.
z General fl uid dynamics simulations. Right now, fl uid dynamics falls into
the realm of specialized simulation libraries. However, this is an active
area of research, and it may well eventually fi nd its way into mainstream
physics engines.12.6. A Look Ahead: Advanced Physics Features