LACS09_TwoBodyG.java

//TwoBodyG.java     MrG     2012.0621 (work in progress)
public class TwoBodyG
{
    private double size;
    private BodyG[] planets;

    public TwoBodyG(double size, BodyG b1, BodyG b2)
    {
        this.size = size;
        StdDraw.setXscale(-size,size);
        StdDraw.setYscale(-size,size);
        planets = new BodyG[2];
        planets[0]=b1;
        planets[1]=b2;
    }

    public void draw()
    {
        planets[0].draw();
        planets[1].draw();
    }

    public void move(double time)
    {
        Vector f0 = new Vector(0,0);
        f0.sum(planets[0].pullFrom(planets[1]));
        f0.sum(planets[1].pullFrom(planets[0]));
        planets[0].move(f0,time);

        Vector f1 = new Vector(0,0);
        f1.sum(planets[1].pullFrom(planets[0]));
        f1.sum(planets[0].pullFrom(planets[1]));
        planets[1].move(f1,time);
    }
}