/*
 -------------------------------------------------------------------------
 
    File: PocketSpiroGraph.java

    Author: David R. Chung
            dchung@soli.inav.net
            http://soli.inav.net/~dchung    
 -------------------------------------------------------------------------
*/

import java.awt.*;
import java.awt.Color;
import java.lang.Math ; 

public class PocketSpiroGraph 
      extends java.applet.Applet     // applet base class
    {
    
    Button             startButton ;
    DrawingPanel    drawingPanel ;
    

    public void init() 
        {
        resize(200,225);                
        setLayout( new BorderLayout()) ;

        startButton  = new Button( "New Image" ) ;
        drawingPanel = new DrawingPanel()    ;
        
        add( "Center", drawingPanel  ) ;
        add( "South",  startButton ) ;

        drawingPanel.newSpirograph() ;
        }
 
        
    public boolean handleEvent(Event evt)
        {
        if("New Image".equals(evt.arg))
            {
            drawingPanel.newSpirograph() ;            
            return true ;
            }
        return false ;
        }


    }

class DrawingPanel extends Panel
{

Dimension q = size();
PolarPlot graph = new PolarPlot( 5, 5, 190, 1.0 ) ;

double a, b, c ;

public void init() 
      {
       a = Math.round(Math.random()*1000) ;
       b = Math.round(Math.random()*1000) ;
       c = Math.round(Math.random()*1000) ;
       }

public void newSpirograph()
    {
       a = Math.round(Math.random()*1000) ;
       b = Math.round(Math.random()*1000) ;
       c = Math.round(Math.random()*1000) ;

    repaint() ;
    }

public void paint(Graphics g) 
    {
    Dimension d = size();

    g.setColor( new Color( 229,215, 144 ) ) ;
    g.fillRect(0,0, d.width - 1, d.height - 1);
    g.setColor( Color.black ) ;
    g.drawRect(0,0, d.width - 1, d.height - 1);

    for ( double theta = 0.0; theta < 360.0;theta += 0.02 )
        {
        graph.Plot(  g, Math.sin( a * theta ) * Math.cos( b * (theta + c) ), theta, Color.red ) ;
        }

    }


}


class PolarPlot
{

int m_UpperLeftX  ;
int m_UpperLeftY  ;

int m_Width       ;

int m_OriginX       ;
int m_OriginY     ;

double m_ScaleFactor ;

int m_OffsetX ;
int m_OffsetY ;

public PolarPlot( int upperLeftX, int upperLeftY, int width, double maxR )
    {
    
    m_UpperLeftX     = upperLeftX ;
    m_UpperLeftY     = upperLeftY ;
    
    m_Width          = width      ;

    m_OriginX         = upperLeftX + width  / 2 ;        
    m_OriginY        = upperLeftY + width  / 2 ;

    m_ScaleFactor    = (double)width / ( 2.0 * maxR ) ;

    m_OffsetX = upperLeftX + width / 2 ;
    m_OffsetY = upperLeftY + width / 2 ;

    }    


public void Plot( Graphics g, double r, double theta, Color color ) 
    {

    g.setColor( color ) ;
    
    int x = (int)( m_ScaleFactor * r * Math.cos( theta ) ) + m_OffsetX ;
    int y = (int)( m_ScaleFactor * r * Math.sin( theta ) ) + m_OffsetY ;
                                                              
    g.drawLine( x, y, x, y ) ;

    }


}