recursion sierpinskys triangle - HELP!!

hi!

i have to write a gui window, which draws sierpinskys triangle recursively, i have one main class:

package triangleMod;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Point;

import javax.swing.JFrame;


public class Main extends Frame{
   
    static Point a;
    static Point b;
    static Point c;
    static Triangle tryAngle;
    static JFrame frame;
   

    private static final long serialVersionUID = 1L;

    //frame setup taken from:
    //http://java.sun.com/docs/books/tutorial/uiswing/examples/components/FrameDemoProject/src/components/FrameDemo.java
    private static void createAndShowGUI() {
        //Create and set up the window.
        frame = new JFrame("Fractal: Sierpinski's Triangle");
        a = new Point(0, 443);
        b = new Point(512, 443);
        c = new Point(256, 0);
        tryAngle = new Triangle(a, b, c);
       
        tryAngle.setPreferredSize(new Dimension(514, 446));
        //frame.add(tryAngle);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.getContentPane().add(tryAngle);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
           //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

AND MORE IMPORTANT: the triangle class with the recursion

package triangleMod;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Point;

class Triangle extends Component{

    private static final long serialVersionUID = 1L;

    //A, B, C initial triangle-points, assigned in the constructor
    private Point A, B, C;
    //points for the 3 new inner triangles in the current recursive step
    private Point A1, B1, C1, A2, B2, C2, A3, B3, C3;

    public Triangle(Point a, Point b, Point c){
        this.A = a;
        this.B = b;
        this.C = c;
        }
   
    //helper var for recursion termination
    int i= 300;
   
    //draws fractal
    public void drawFractal(Graphics g, Point a, Point b, Point c){
       
        /**
         * draw outer triangle
         **/
       
        //AB
        g.drawLine(a.x, a.y, b.x, b.y);
        //AC
        g.drawLine(a.x, a.y, c.x, c.y);
        //BC
        g.drawLine(b.x, b.y, c.x, c.y);
       
        /**
         * Points of the 3 new triangles get assigned
         **/
       
        //lower left triangle coordinates
        A1 = new Point(A.x, A.y);
        B1 = new Point(c.x, b.y);
        C1 = new Point((a.x+c.x)/2, (c.y+a.y)/2);
       
        //lower right triangle coordinates
        A2 = new Point(c.x, b.y);
        B2 = new Point(B.x, B.y);
        C2 = new Point((c.x+b.x)/2, (c.y+a.y)/2);
       
        //upper triangle coordinates
        A3 =  new Point((a.x+c.x)/2, (c.y+a.y)/2);
        B3 = new Point((c.x+b.x)/2, (c.y+a.y)/2);
        C3 = new Point(C.x, C.y);
       
        /**
         * draw inner reversed triangle
         **/
       
        //AB
        g.drawLine(A3.x, A3.y, B3.x, B3.y);
        //AC
        g.drawLine(A3.x, A3.y, A2.x, A2.y);
        //BC
        g.drawLine(B3.x, B3.y, A2.x, A2.y);
       
        /**
         * rekusive method calls for the three new triangles
         **/
       
    //termination condition not set correctly, helper var i used for testing
        while (i-->0) {           
           
            drawFractal(g, A1, B1, C1);
            //drawFractal(g, A2, B2, C2);
            //drawFractal(g, A3, B3, C3);
           
        }
    }

    public void paint(Graphics g){
        drawFractal(g, A, B, C);
    }
}

THE PROBLEM:

as you see, in the whle loop i commented two of the recursive calls out, if I just have one of the 3 calls (no matter which one of the three), it works, the triangles in that direction are drawn. but if I have two or three of the recursive call, it does not work, it's not drawing the triangles i want. the three recursive calls seem to affect each other in a way i don't want.

i just don't get each of the recursive drawing just the triangles they do draw, when i just have the one recursive call in the while loop. i thought it should work, as i have separated, always newly defined points for A1, B1, C1 and so on...

maybe i am misunderstanding how the java stack recursion works, can anyone maybe test my code and give any help??

would really be cool, thx a lot

btw: i know that the condition in the while loop is not the right recirsive base condition, but i didn't think about the right one yet and just used it like it is there for testing, i want to fix that if my method principally works correct

jrobw

Newbie Poster

13 posts since Dec 2008

Reputation Points: 10

Solved Threads: 0

recursion sierpinskys triangle - HELP!!

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