//***************************************************************
//  KochPanel.java       Authors: Lewis and Loftus
//                       Updated: Bary W Pollack
//
//  Creates a drawing surface on which to paint a Koch Snowflake.
//***************************************************************

import java.awt.*;
import javax.swing.JPanel;

public class KochPanel extends JPanel {

    //------------------------------------------------------------
    //  Sets the initial fractal order to the value specified.
    //------------------------------------------------------------
    public KochPanel(int current) {
        this.current = current;
        setBackground(Color.black);
        setPreferredSize(new Dimension(PANEL_WIDTH, PANEL_HEIGHT));
    }

    //------------------------------------------------------------
    //  Draws the fractal recursively. Base case is an order of 1
    //  for which a simple straight line is drawn. Otherwise three
    //  intermediate points are computed, and each line segment is
    //  drawn as a fractal.
    //------------------------------------------------------------
    public void drawFractal(int order, int x1, int y1,
        int x5, int y5, Graphics page) {
        int deltaX, deltaY, x2, y2, x3, y3, x4, y4;

        if (order == 1)
            page.drawLine(x1, y1, x5, y5);
        else {
            deltaX = x5 - x1;        // distance between end points
            deltaY = y5 - y1;

            x2 = x1 + deltaX / 3;    // one third
            y2 = y1 + deltaY / 3;
            x3 =(int)((x1+x5)/2 + SQ *(y1-y5));  // tip of projection
            y3 =(int)((y1+y5)/2 + SQ *(x5-x1));

            x4 = x1 + deltaX * 2/3;  // two thirds
            y4 = y1 + deltaY * 2/3;

            // recursive calls
            drawFractal(order-1, x1, y1, x2, y2, page);
            drawFractal(order-1, x2, y2, x3, y3, page);
            drawFractal(order-1, x3, y3, x4, y4, page);
            drawFractal(order-1, x4, y4, x5, y5, page);
        }
    }

    //------------------------------------------------------------
    //  Performs the initial calls to the drawFractal method.
    //------------------------------------------------------------
    public void paintComponent(Graphics page) {
        super.paintComponent(page);
        page.setColor(Color.green);
        drawFractal(current, TOPX, TOPY, LEFTX, LEFTY, page);
        drawFractal(current, LEFTX, LEFTY, RIGHTX, RIGHTY, page);
        drawFractal(current, RIGHTX, RIGHTY, TOPX, TOPY, page);
    }

    //------------------------------------------------------------
    //  Sets the fractal order to the value specified.
    //------------------------------------------------------------
    public void setOrder(int order) {
        current = order;
    }

    //------------------------------------------------------------
    //  Returns the current order.
    //------------------------------------------------------------
    public int getOrder() {
        return current;
    }

    private final int PANEL_WIDTH  = 400;
    private final int PANEL_HEIGHT = 400;

    private final double SQ = Math.sqrt(3.0) / 6;

    private final int TOPX   = 200, TOPY   = 20;
    private final int LEFTX  = 60,  LEFTY  = 300;
    private final int RIGHTX = 340, RIGHTY = 300;
    private int current;    // current order
}