import java.awt.*;

public class Planet
/** Part of Applet Solar, one planet of a solar system
	Lin Jensen
	7 June 2005
*/
{
   private double radius;	// in astronomical units
   private double period;	// in years
   private Color color;
   private int size;		// in pixels
   private double theta = 0.0;
   private double dt;		// change in theta each draw
   private double scale
   ;

   Planet(double orbit, Color hue, int pix)
   {	radius=orbit;
   	color=hue;
	size=pix;
	period = Math.pow(radius, 1.5); //Kepler's law
	dt = Solar.step/period;		// distant planets move slowly
   }

   public void draw(Graphics g)
   {
      scale = radius*Solar.half/3;
   //System.out.println("Scale = "+ scale);
      double x, y;
      int ix, iy;
      theta += dt;
      x= radius*Math.cos(theta);
      y= radius*Math.sin(theta);	//for now circular orbit
      ix = Solar.half + (int)(scale*x) ;
      iy = Solar.half + (int)(scale*y);
      g.setColor(color);
      g.fillOval(ix-size/2, iy-size/2, size, size);
   }
}