// colorw.java   color wheel based on phase angle
//            copied from 1/1/97 JSS initial version
//            tested on Linux, MacOSX, Windows
// may be compiled and linked using  javac -cp . colorw.java

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.*;

public class colorw extends Frame
{
  double Pi = 3.14159265358979323846;
  int width=400;
  int height=400;

  colorw()
  {
    setTitle("colorw.java");
    setSize(width,height);
    setBackground(Color.white);
    setForeground(Color.black);
    addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e)
      {
        System.exit(0);
      }
    });
    setVisible(true);
    repaint();
  } // colorw

  public void paint(Graphics g)
  {
    double x1, x2, y1, y2;
    float A, AA, AAA; // temporaries 
    float R, G, B;    // red, green, blue intensities computer 
    double radius_1 = 160.0;
    double radius_2 =  60.0;
    int cnt = 0;
    int ncont = 2;
    double xc = 200.0;
    double yc = 210.0;

    g.setColor(Color.black);
    // for(int i=0; i<nxy; i++) // data point location
    // {
    //   g.drawOval(scalex(xx[i]), scaley(yy[i]), 2, 2);
    // }

    g.drawString("colorw.java", 20, 50);

    // g.fillRect(10,50+20*i,30,15);
    // g.setLineWidth(5);

    A = -1.0f;
    while(A < 1.0f)  // walk the angle in bams around the circle 
    {
      // A = arctan(Y, X)/PI   for normalized angle from X-Y plot        
      // get double R,G,B  R==1 at A==0, G==1 at A==2/3, B==1 at A==-2/3 
	R = (float)(1.0 - Math.abs(A));
      AA = A - 2.0f/3.0f;
      if(AA < -1.0f) AA = 2.0f+AA;
      G = (float)(1.0 - Math.abs(AA));
      AA = A + 2.0f/3.0f;
      if(AA > 1.0f) AA = 2.0f-AA;
      B = (float)(1.0 - Math.abs(AA));

      // boost low end and normalize (this brightens colors) 
      R = R+0.2f;
      G = G+0.2f;
      B = B+0.2f;
      AAA = Math.max(R, G);
      AAA = Math.max(AAA, B);
      R = R/AAA;
      G = G/AAA;
      B = B/AAA;
    
      // set color
      g.setColor(new Color(R, G, B));

      // compute line ends 
      x1 = radius_1 * Math.cos(A * Pi);
      y1 = radius_1 * Math.sin(A * Pi);
      x2 = radius_2 * Math.cos(A * Pi);
      y2 = radius_2 * Math.sin(A * Pi);
      g.drawLine((int)(xc+x1), (int)(yc+y1), (int)(xc+x2), (int)(yc+y2));
      A = A + 0.005f;  // 240 lines, 0.01  200 lines -1.0 to 1.0 
    }
  } // end paint

  public static void main(String args[])
  {
    new colorw();
  }
} // end colorw.java