//Rosette.java

import java.awt.*;
import java.awt.event.*;    //ActionListener "interface"
import javax.swing.*;

public class Rosette extends JApplet implements ActionListener {
    //i.e. this class does what's req'd by the interface

    int sides;
    int angleIncrement;
    int loops=0;
    int animationDelay;        //** millisecond delay
    Timer animationTimer;     //** Timer drives animation
    
    public void init() {
	String input;

	input = JOptionPane.showInputDialog("Enter # of sides of regular polygon");
	sides = Integer.parseInt(input);
	
	input = JOptionPane.showInputDialog("Enter animation delay in ms");
	animationDelay = Integer.parseInt(input);

	input = JOptionPane.showInputDialog("Enter angular increment in degrees");
	angleIncrement = Integer.parseInt(input);

	startAnimation();  //*** begin animation
    }

    
    //** will be called once every animationDelay ms
    public void paint(Graphics g) {
	super.paint(g);   //clears screen each call

	int radius=getWidth()<getHeight() ? getWidth()/2 : getHeight()/2; 
	int xcenter=getWidth()/2, ycenter=getHeight()/2;
	
	int[][] points = new int[sides][2];

	//calculate the coords of the points
	double angle;     //radians
	double offset = loops * (angleIncrement*2*Math.PI / 360);
	//	double offset = loops*2*Math.PI/(4*sides);
	for (int i=0; i<sides; i++) {
	    angle = i * 2 * Math.PI / sides + offset;
	    points[i][0] = (int) (Math.cos(angle) * radius + xcenter);
	    points[i][1] = (int) (Math.sin(angle) * radius + ycenter);
	}
	loops++;
	g.setColor(Color.RED);
	/*
	g.setColor(new Color((int)(Math.random()*256),
			     (int)(Math.random()*256),
			     (int)(Math.random()*256)));
	*/
	//draw a line between each pair of points
	for (int i=0; i<sides-1; i++)
	    for (int j=i+1; j<sides; j++)
		g.drawLine(points[i][0],points[i][1],
			   points[j][0],points[j][1]);
	
    }

    //** Generic animation stuff:  use this as is for any animation.
    
    // respond to Timer's event.  
    //Must have this method if implementing ActionListener
    public void actionPerformed( ActionEvent actionEvent ) {
	repaint(); // repaint animator.  calls paint method
    }
    
    // start or restart animation
    public void startAnimation() {
	if ( animationTimer == null ) {
	    animationTimer = new Timer( animationDelay, this );
	    animationTimer.start();
	}
	else // continue from last image displayed
	    if ( ! animationTimer.isRunning() )
		animationTimer.restart();
    }
    
    // stop animation timer
    public void stopAnimation() {
	animationTimer.stop();
    }
}