import objectdraw.*;
import java.awt.*;

/*
 * An active object to draw Spirals.  Demonstrates
 * how to pass parameters to a Spiral that then get
 * used in the run() method.
 */
public class Spiral extends ActiveObject {

  private final static double DELAY = 2;
  private final static double MAX_THETA = 20 * Math.PI;
  private static final double THETA_STEP = 0.05;

  // Information provided by the window controller
  //  to tell us where to draw and what we should look like.
  private Location center;
  private double magnitude;
  private double bumps;

  // the canvas we are drawing on
  private DrawingCanvas canvas;

  /*
   * Create a new spiral with the given center, number
   * of bumps and magnitude.
   */
  public Spiral(Location aCenter, double aMag, double aBump, DrawingCanvas aCanvas) {  

    center = aCenter;
    canvas = aCanvas;
    bumps = aBump;
    magnitude = aMag;

    this.start();
  }

  public void run() {
    Location lastPoint = center;

    double theta = 0;

    // The loop is the same as the loop from the spiral code
    // that draws it all at once - except for the call to pause...
    while (theta < MAX_THETA) {

      double radius = theta * (1 + Math.sin(bumps * theta) * magnitude);

      // Convert polar to cartesian
      Location newPoint = 
        new Location(center.getX() + radius * Math.cos(theta),
                     center.getY() + radius * Math.sin(theta));

      new Line(lastPoint, newPoint, canvas);

      pause(DELAY);

      lastPoint = newPoint;

      theta = theta + THETA_STEP;
    }
  }
}