Koch.java

/*************************************************************************
 *  Compilation:  javac Koch.java
 *  Execution:    java Koch N
 *  Dependencies: StdDraw.java
 *  
 *  Plot an order N Koch snowflake.
 *
 *  % java Koch 5
 *
 *************************************************************************/


public class Koch {

    // Koch curve of order n
    public static void koch(int n, double size) {
        if (n == 0) StdDraw.goForward(size);
        else {
            koch(n-1, size);
            StdDraw.rotate(60);
            koch(n-1, size);
            StdDraw.rotate(-120);
            koch(n-1, size);
            StdDraw.rotate(60);
            koch(n-1, size);
        }
    }

    public static void main(String args[]) {
        int N = Integer.parseInt(args[0]);
        int width = 512;
        int height = (int) (2 * width / Math.sqrt(3));
        double size = width / Math.pow(3.0, N);
        StdDraw.create(width, height);

        // three Koch curves in the shape of an equilateral triangle
        StdDraw.go(0, width * Math.sqrt(3) / 2);
        StdDraw.penDown();
        koch(N, size);
        StdDraw.rotate(-120);
        koch(N, size);
        StdDraw.rotate(-120);
        koch(N, size);
        StdDraw.show();
    }
}