Game Development Reference
In-Depth Information
Hockey
One of the unique aspects about hockey is that it is played on ice. The puck used in hockey is
not round, but instead is a hard rubber cylindrical disk. Most of the time the puck will either be
sliding over the ice or flying through the air. To model the sliding puck requires accounting for
the friction between the ice and puck. The flight of a puck in the air will be affected by the forces
due to gravity, aerodynamic drag, and possibly spin. Unless the game simulation is set outdoors,
wind effects can be ignored.
Tennis
The final sport we will briefly discuss is tennis, where players must hit the ball over a net and
keep it inside the opponent's side of the court. Spin is very important in tennis. Putting topspin
on the ball allows players to hit the ball harder without hitting the ball out of bounds. In devel-
oping a tennis simulation, collisions between the ball and ground would have to be modeled as
well as possibly collision of the ball and top of the net.
Summary
In this chapter, you learned how to apply some basic Newtonian mechanics and kinematics to
the problem of developing sports simulations. Specific details were presented on how to model
golf, soccer, basketball, and baseball—sports that involve hitting, kicking, or throwing balls.
The basic physics is really very similar for many sports simulations. It's just a matter of knowing
which forces to consider.
Here are some specific points to remember about creating sports simulations:
•
When a ball (or person for that matter) is in the air, it can be treated as projectile and will
be subject to the forces due to gravity, aerodynamic drag, wind, and spin.
•
The Magnus force due to spin is very important for the sports of golf, soccer, and base-
ball. The magnitude of the force due to spin can be obtained by determining the lift
coefficient for the object in question.
•
At times the effects of wind and spin can be ignored, for example, when simulating the
flight of a basketball.
•
There are also instances, for example soccer and baseball, when it is probably better for
game programming purposes not to try to model the initial collision, but rather to begin
the simulation by specifying the post-collision velocity, spin rate, and spin axis of the ball.
References
1. S. Atkinson, Brown, J., and McElheny, J., The Physics of Golf,
www.homewood.k12.al.us/
compsci/projects98/eteam
.
2. P.W. Bearman and Harvey, J.K., “Golfball Aerodynamics,”
Aeronautical Quarterly
, May 1976,
pp. 112-122.
