COS126

• Download NestedCircles.java

/******************************************************************************
 * Name:
 * NetID:
 * Precept:
 *
 * Description: Draws an n-level set of nested circles in random colors.
 ****************************************************************************/

public class NestedCircles {
    
    // draw a circle with some embellishments
    // the center is (x, y) with the specified radius
    public static void fancyCircle(double x, double y, double radius) {

        // use one of two color pairs at random
        int randomBit = (int) (Math.random() * 2);  // equally likely 0 or 1
 
        // this is the colour that will fill the circle
        if (randomBit == 0)
            StdDraw.setPenColor(StdDraw.CYAN);
        else 
            StdDraw.setPenColor(StdDraw.ORANGE);
        StdDraw.filledCircle(x, y, radius);
 
        // this is the colour for the circle's border
        if (randomBit == 0)
            StdDraw.setPenColor(StdDraw.BLUE);
        else
            StdDraw.setPenColor(StdDraw.RED);
        StdDraw.circle(x, y, radius);
    }
    
    // draw a nested circle of order n, centred at (x, y) with
    // the specified radius
    public static void draw(int n, double x, double y, double radius) {
        if (n == 0) return;
        fancyCircle(x, y, radius);
        
        double halfRadius = radius/2;

        // recursively draw two nested circles of order n-1
        draw(n-1, x - halfRadius, y, halfRadius);
        draw(n-1, x + halfRadius, y, halfRadius);
    }
    
    // takes an integer command-line argument n and plots an order n circle
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);
        double x = 0.5, y = 0.5;      // biggest circle centred at (0.5, 0.5)
        draw(n, x, y, 0.5);           // radius fills up [0,1] x [0,1] view
    }
}