throttlecontroller.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
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.jme.input.controls.controller;

import com.jme.input.controls.GameControl;
import com.jme.scene.Controller;
import com.jme.scene.Spatial;

/**
 * ThrottleController manages forward and backward thrust on a Spatial
 * 
 * spatial - the object throttle is being applied to
 * forward - the GameControl that effects forward thrust
 * maxForwardThrottle - the maximum throttle that can be achieved in a
 * 						forward motion
 * reverse - the GameControl that effects reverse thrust
 * maxReverseThrottle - the maximum throttle that can be achieved in a
 * 						reverse motion
 * deadZone - the area on both sides of 0.0f that automatically gets
 * 			  counted as 0.0f (for Joystick throttles with high sens.)
 * multiplier - the multiplier that defines how quickly maximum thrust
 * 				can be achieved
 * degradation - the multiplier that defines how quickly the thrust will
 * 				 degrade back to zero
 * alwaysDegrade - if this is true, even when using a key/button to increase
 * 				   throttle it will continually degrade toward 0.0f
 * axis - the axis on the spatial the throttle should be applied to
 * 
 * @author Matthew D. Hicks
 */
public class ThrottleController extends Controller {
	private static final long serialVersionUID = 1L;
	
	private Spatial spatial;
	private GameControl forward;
	private float maxForwardThrottle;
	private GameControl reverse;
	private float maxReverseThrottle;
	private float deadZone;
	private float multiplier;
	private float degradation;
	private boolean alwaysDegrade;
	private Axis axis;
	
	private long zeroEncountered;
	
	private float currentThrottle;
	
	// TODO should afterburner be added to this?
	public ThrottleController(Spatial spatial, 
					 		  GameControl forward,
					 		  float maxForwardThrottle,
					 		  GameControl reverse,
					 		  float maxReverseThrottle,
					 		  float deadZone,
					 		  float multiplier,
					 		  float degradation,
					 		  boolean alwaysDegrade,
					 		  Axis axis) {
		this.spatial = spatial;
		this.forward = forward;
		this.maxForwardThrottle = maxForwardThrottle;
		this.reverse = reverse;
		this.maxReverseThrottle = maxReverseThrottle;
		this.deadZone = deadZone;
		this.multiplier = multiplier;
		this.degradation = degradation;
		this.alwaysDegrade = alwaysDegrade;
		this.axis = axis;
	}
	
	public GameControl getForward() {
		return forward;
	}
	
	public GameControl getReverse() {
		return reverse;
	}
	
	public float getCurrentThrottle() {
		return currentThrottle;
	}
	
	public float getThrust() {
		return forward.getValue() - reverse.getValue();
	}
	
	public void update(float time) {
		if (System.currentTimeMillis() < zeroEncountered + 50) return;
		
		float value = getThrust();
		if ((value < deadZone) && (value > -deadZone)) {
			value = 0.0f;
		}
		float delta = time * multiplier;
		float max = maxForwardThrottle;
		float min = maxReverseThrottle;
		if (value > 0.0f) {
			max = maxForwardThrottle * value;
		} else if (value < 0.0f) {
			min = maxReverseThrottle * -value;
		} else {
			if (currentThrottle > 0.0f) {
				min = 0.0f;
			} else {
				max = 0.0f;
			}
		}
		if (value < 0.0f) {
			delta = -delta;
		} else if (value == 0.0f) {
			if (currentThrottle > 0.0f) {
				if ((forward.hasTrueAxis()) || (alwaysDegrade)) {
					delta = -delta * degradation;		// Degrade back to zero
				} else {
					delta = 0.0f;
				}
			} else if (currentThrottle < 0.0f) {
				if ((reverse.hasTrueAxis()) || (alwaysDegrade)) {
					// Degrade back to zero
					delta *= degradation;
				} else {
					delta = 0.0f;
				}
			}
		}
		if ((currentThrottle > 0.0f) && (currentThrottle + delta < 0.0f)) {
			currentThrottle = 0.0f;
			zeroEncountered = System.currentTimeMillis();
		} else if ((currentThrottle < 0.0f) && (currentThrottle + delta > 0.0f)) {
			currentThrottle = 0.0f;
			zeroEncountered = System.currentTimeMillis();
		} else {
			currentThrottle += delta;
		}
		if (currentThrottle > max) {
			currentThrottle = max;
		} else if (currentThrottle < min) {
			currentThrottle = min;
		}
		if (currentThrottle != 0.0f) {
			if (axis == Axis.X) {
				spatial.getLocalTranslation().addLocal(spatial.getLocalRotation().getRotationColumn(0).mult(currentThrottle));
			} else if (axis == Axis.Y) {
				spatial.getLocalTranslation().addLocal(spatial.getLocalRotation().getRotationColumn(1).mult(currentThrottle));
			} else if (axis == Axis.Z) {
				spatial.getLocalTranslation().addLocal(spatial.getLocalRotation().getRotationColumn(2).mult(currentThrottle));
			} else {
				throw new RuntimeException("Unknown axis: " + axis);
			}
		}
	}
}