/*
 * $RCSfile: Interpolator.java,v $
 *
 * Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
 *
 * Use is subject to license terms.
 *
 * $Revision: 1.5 $
 * $Date: 2007/02/09 17:18:06 $
 * $State: Exp $
 */

package javax.media.j3d;


import java.util.Vector;

/**
 * Interpolator is an abstract class that extends Behavior to provide
 * common methods used by various interpolation subclasses.  These
 * include methods to convert a time value into an alpha value (A
 * value in the range 0 to 1) and a method to initialize the behavior.
 * Subclasses provide the methods that convert alpha values into
 * values within that subclass' output range.
 */

public abstract class Interpolator extends Behavior {

    // This interpolator's alpha generator
    Alpha alpha;


    /** 
     * Default WakeupCondition for all interpolators. The
     * wakeupOn method of Behavior, which takes a WakeupCondition as
     * the method parameter, will need to be called at the end
     * of the processStimulus method of any class that subclasses
     * Interpolator; this can be done with the following method call: 
     * wakeupOn(defaultWakeupCriterion).
     */
    protected WakeupCriterion defaultWakeupCriterion = 
	(WakeupCriterion) new WakeupOnElapsedFrames(0);


    /**
     * Constructs an Interpolator node with a null alpha value.
     */
    public Interpolator() {
    }


    /**
     * Constructs an Interpolator node with the specified alpha value.
     * @param alpha the alpha object used by this interpolator.
     * If it is null, then this interpolator will not run.
     */
    public Interpolator(Alpha alpha){
	this.alpha = alpha;
    }


    /**
      * Retrieves this interpolator's alpha object.
      * @return this interpolator's alpha object
      */
    public Alpha getAlpha() {
	return this.alpha;
    }


    /**
     * Set this interpolator's alpha to the specified alpha object.
     * @param alpha the new alpha object.  If set to null,
     * then this interpolator will stop running.
     */
    public void setAlpha(Alpha alpha) {
	this.alpha = alpha;
	VirtualUniverse.mc.sendRunMessage(J3dThread.RENDER_THREAD);
    }


    /**
     * This is the default Interpolator behavior initialization routine.
     * It schedules the behavior to awaken at the next frame.
     */
    public void initialize() {
	// Reset alpha
	//alpha.setStartTime(J3dClock.currentTimeMillis());

	// Insert wakeup condition into queue
	wakeupOn(defaultWakeupCriterion);
    }


   /**
     * Copies all Interpolator information from
     * <code>originalNode</code> into
     * the current node.  This method is called from the
     * <code>cloneNode</code> method which is, in turn, called by the
     * <code>cloneTree</code> method.<P> 
     *
     * @param originalNode the original node to duplicate.
     * @param forceDuplicate when set to <code>true</code>, causes the
     *  <code>duplicateOnCloneTree</code> flag to be ignored.  When
     *  <code>false</code>, the value of each node's
     *  <code>duplicateOnCloneTree</code> variable determines whether
     *  NodeComponent data is duplicated or copied.
     *
     * @exception RestrictedAccessException if this object is part of a live
     *  or compiled scenegraph.
     *
     * @see Node#duplicateNode
     * @see Node#cloneTree
     * @see NodeComponent#setDuplicateOnCloneTree
     */
    void duplicateAttributes(Node originalNode, boolean forceDuplicate) {
        super.duplicateAttributes(originalNode, forceDuplicate);
	
	Interpolator it = (Interpolator) originalNode;

	Alpha a = it.getAlpha();
	if (a != null) {
  	    setAlpha(a.cloneAlpha());
	}
    }
}
