//****************************************************************************
//Title: DrawACircle
//Written By: Vincent Ford
//Date : 1-31-99
//Assignment: 2 for the 15a lab
//Problem Description: Create an applet that draws a circle and when the applet
//is redrawn the circle changes color from red to black and back again
//
//  Java Applet version 
//  Author: Achim E Karger
//  Course: CSCI 111 Java I
//  Assignment: Lab 2
//  Date:   February 3, 2008
//  compiler JCreator LE 
//  Client web application: lab2.html
//  The original version of the Java Applet "DrawACircle.java  downloaded from 
//  ~amk/courses/csci15a/15a_examples/DrawACircle.java needed debugging
//  (used JCreator LE) 
//
//*****************************************************************************

//use the  applet and abstract windowing libraries

//import statements

import java.awt.*;
import java.applet.*;


//define two classes ComputeUnitCircle and DrawACircle

//****************************************************************************
//****************************** ComputeUnitCircle ***************************
//****************************************************************************

//This class computes the x and y location along the unit circle
//The unit circle is discussed in any trigonometry text

class ComputeUnitCircle
{
	//compute the x value along the unit circle
	//inputs are the radian angle ( 0 to 2 pi)
	//outputs are the x value along the circle
	//uses the java.lang.Math class to compute the cos of the angle
	double ComputeX( double RadianAngle)
	{
		return Math.cos(RadianAngle);
	}
	
	//compute the y value along the unit circle
	//inputs are the radian angle ( 0 to 2 pi)
	//outputs are the y value along the circle
	//uses the java.lang.Math class to compute the sin of the angle
	double ComputeY(double RadianAngle)
	{	
		return Math.sin(RadianAngle);
		
}
}
//****************************************************************************
//*********************** end of ComputeUnitCircle ***************************
//****************************************************************************

//****************************************************************************
//****************************** DrawACircle *********************************
//****************************************************************************

//This class is creates an applet which will display a circle that changes color 
//from red to black and back again each time it is painted

public class DrawACircle extends Applet
{
	ComputeUnitCircle myCircle=new ComputeUnitCircle();
	int lastx=50;
	int lasty=25;
	int x=0;
	int y=0;
	boolean z=true;//not very meaningful variable name but not an error

	//this function is called each time the applet must be repainted 
	//because of an event like a window or cursor being moved over the 
	//applet

	public void paint(Graphics g)
	{
		if(z) 	//if z is true do the following 
		{
			z=false;
			g.setColor(Color.red);//change pen color to red
		}
		else	//if z is false do the following
		{
			z=true;
			g.setColor(Color.black);//change pen color to black
		}
		
		//draw 360 line segments that approximate a circle
		//loop 360 times and draw a line connecting around the circle
		for( int degrees=0; degrees<361;degrees++)
		{
			//compute next point along the circle
		x=(int)(myCircle.ComputeX((double)degrees/180*3.14)*24+25);
		y=(int)(myCircle.ComputeY((double)degrees/180*3.14)*24+25);

			//draw a line from previos end point to next point
			g.drawLine(lastx,lasty,x,y);

			lastx=x;//beginning of next line 
			lasty=y;

			//debugging code that displays in the console 
		System.out.println("degrees="+degrees+" x="+x + " y="+y);
			System.out.println("z="+z);
		}
			
	}
}
//****************************************************************************
//*********************** end of DrawACircle *********************************
//****************************************************************************