keynodebackwardaction.java

java 3d game jme 工程开发源代码

/*
 * Copyright (c) 2003-2009 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors 
 *   may be used to endorse or promote products derived from this software 
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jme.input.action;

import com.jme.math.Vector3f;
import com.jme.scene.Spatial;

/**
 * <code>KeyNodeBackwardAction</code> defines an action to move a
 * <code>Spatial</code> node along it's negative direction vector. The speed
 * of the node is defined by the speed and the value set in the
 * <code>performAction</code> method. The speed is set with construction or
 * the <code>setSpeed</code> method. This can be thought as units/second.
 * 
 * @author Mark Powell
 * @version $Id: KeyNodeBackwardAction.java,v 1.17 2007/03/06 15:09:31 nca Exp $
 */
public class KeyNodeBackwardAction extends KeyInputAction {
    //the node to manipulate
    private Spatial node;
    //temporary vector for multiplications
    private static final Vector3f tempVa = new Vector3f();

    /**
     * Constructor creates a new <code>KeyNodeBackwardAction</code> object.
     * During construction, the node to direct and the speed at which to move
     * the node is set.
     * 
     * @param node
     *            the node that will be affected by this action.
     * @param speed
     *            the speed at which the camera can move.
     */
    public KeyNodeBackwardAction(Spatial node, float speed) {
        this.node = node;
        this.speed = speed;
    }

    /**
     * <code>performAction</code> moves the node along it's negative direction
     * vector at a speed of movement speed * time. Where time is the time
     * between frames and 1 corresponds to 1 second.
     * 
     * @see com.jme.input.action.InputActionInterface#performAction(InputActionEvent)
     */
    public void performAction(InputActionEvent evt) {
        Vector3f loc = node.getLocalTranslation();
        loc.subtractLocal(node.getLocalRotation().getRotationColumn(2, tempVa)
                .multLocal(speed * evt.getTime()));
        node.setLocalTranslation(loc);
    }
}