// Trajectory for a moving object

package ciips.animation;

import java.awt.*;
import java.util.*;

/**
 * A trajectory is a set of points which an object will follow on 
 * the screen.
 * As an example, it can be used to define the path followed by
 * a node as it moves down a tree looking for the insertion point
 * It would usually be passed to the
 * <code>animate</code> method from <code>DrawingPanel</code>.
 * @see DrawingPanel#animate
 */
public class Trajectory {
		private static final int MIN_PTS = 10;
    private Vector pts;

		public static final int NO_INTERPOLATION = 0;
		public static final int LINEAR_INTERPOLATION = 1;
		public static final int ARC_INTERPOLATION = 2;
    private int interpolation;

  public Trajectory() {
		pts = new Vector( MIN_PTS );
		interpolation = NO_INTERPOLATION;
    }

	/** Make a new trajectory which starts where the previous one left off
	**/
	public Trajectory( Trajectory previous ) {
		this();
		int last = previous.pts.size() - 1;
		if ( last >= 0 ) pts.add( previous.pts.elementAt( last ) );
		}

	/** Add a Point <CODE>x</CODE> to the trajectory **/
	public void addPoint( Point x ) {
		// pts.add( x );
		pts.addElement( x );
    }

	/** Make an object move to a point <CODE>offset</CODE> 
			from another one
	**/
	public void addPoint( DrawingObj a, Point offset ) {
		Point x = new Point( a.getX()+offset.x, a.getY()+offset.y );
		// pts.add( x );
		pts.addElement( x );
    }

	/** Get the points - used by <CODE>animate</CODE> */
	public Point getPoint( int k ) { 
		return (Point)(pts.elementAt(k)); 
		}

	/** Get the points - used by <CODE>animate</CODE> */
	public Vector getPoints() {
		return pts;
		}
}