LACS2013-Ball.java

//Ball.java     MrG     2013.0603
import java.awt.Color;
public class Ball
{
    private double r;
    private double rx;
    private double ry;
    private double vx;
    private double vy;
    private Color c;

    public Ball()
    {
        r=Math.random();
        //rx=20*Math.random()-10;
        //ry=20*Math.random()-10;
        rx=0.0;
        ry=0.0;
        int choice = (int)(4*Math.random());
        if(choice==0)
        {
            vx=Math.random()/2;
            vy=Math.random()/2;
        }
        if(choice==1)
        {
            vx=-Math.random()/2;
            vy=Math.random()/2;
        }
        if(choice==2)
        {
            vx=-Math.random()/2;
            vy=-Math.random()/2;
        }
        if(choice==3)
        {
            vx=Math.random()/2;
            vy=-Math.random()/2;
        }
        c=new Color((float)Math.random(),(float)Math.random(),(float)Math.random());
    }

    public void draw()
    {
        StdDraw.setPenColor(c);
        StdDraw.filledCircle(rx,ry,r);
    }

    public void move()
    {
        if(Math.abs(rx)>10)
        {
            vx=-vx;
        }
        if(Math.abs(ry)>10)
        {
            vy=-vy;
        }
        rx+=vx;
        ry+=vy;
    }
}