Game Development Reference
In-Depth Information
As was the case with the golf simulator we developed earlier in this chapter, the Free-Kick
Game requires two classes—the
SoccerBall
class that represents a soccer ball and a
FreeKick
class that defines the GUI. We'll start by looking at the
SoccerBall
class.
Like the
GolfBall
class, the
SoccerBall
class is written as a subclass of the
SpinProjectile
class. The
SoccerBall
class declares one field that will store the value of the air temperature,
which will be used to compute the Reynolds number later in the class. The
SoccerBall
constructor simply calls the
SpinProjectile
constructor.
public class SoccerBall extends SpinProjectile
{
private double temperature;
public SoccerBall(double x0, double y0, double z0,
double vx0, double vy0, double vz0, double time,
double mass, double area, double density, double Cd,
double windVx, double windVy, double rx, double ry,
double rz, double omega, double radius,
double temperature) {
// Call the SpinProjectile class constructor.
super(x0, y0, z0, vx0, vy0, vz0, time, mass, area,
density, Cd, windVx, windVy, rx, ry, rz, omega, radius);
this.temperature = temperature;
}
The
getRightHandSide
method declared in the
SoccerBall
class is similar to the
SpinProjectile
class version with two exceptions: the drag coefficient for the soccer ball is
computed according to Equation (7.54), and the lift coefficient for the Magnus force term is
determined from Equation (7.56). The first part of the method, which is identical to that of the
SpinProjectile
class, is not shown.
// The getRightHandSide() method returns the right-hand
// sides of the six first-order projectile ODEs.
// q[0] = vx = dxdt
// q[1] = x
// q[2] = vy = dydt
// q[3] = y
// q[4] = vz = dzdt
// q[5] = z
public double[] getRightHandSide(double s, double q[],
double deltaQ[], double ds,
double qScale) {
double dQ[] = new double[6];
double newQ[] = new double[6];
