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      1 /*
      2  * Copyright (c) 2009-2010 jMonkeyEngine
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are
      7  * met:
      8  *
      9  * * Redistributions of source code must retain the above copyright
     10  *   notice, this list of conditions and the following disclaimer.
     11  *
     12  * * Redistributions in binary form must reproduce the above copyright
     13  *   notice, this list of conditions and the following disclaimer in the
     14  *   documentation and/or other materials provided with the distribution.
     15  *
     16  * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
     17  *   may be used to endorse or promote products derived from this software
     18  *   without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     23  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
     24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 package com.jme3.system;
     34 
     35 /**
     36  * <code>NanoTimer</code> is a System.nanoTime implementation of <code>Timer</code>.
     37  * This is primarily useful for headless applications running on a server.
     38  *
     39  * @author Matthew D. Hicks
     40  */
     41 public class NanoTimer extends Timer {
     42 
     43     private static final long TIMER_RESOLUTION = 1000000000L;
     44     private static final float INVERSE_TIMER_RESOLUTION = 1f/1000000000L;
     45 
     46     private long startTime;
     47     private long previousTime;
     48     private float tpf;
     49     private float fps;
     50 
     51     public NanoTimer() {
     52         startTime = System.nanoTime();
     53     }
     54 
     55     /**
     56      * Returns the time in seconds. The timer starts
     57      * at 0.0 seconds.
     58      *
     59      * @return the current time in seconds
     60      */
     61     @Override
     62     public float getTimeInSeconds() {
     63         return getTime() * INVERSE_TIMER_RESOLUTION;
     64     }
     65 
     66     public long getTime() {
     67         return System.nanoTime() - startTime;
     68     }
     69 
     70     public long getResolution() {
     71         return TIMER_RESOLUTION;
     72     }
     73 
     74     public float getFrameRate() {
     75         return fps;
     76     }
     77 
     78     public float getTimePerFrame() {
     79         return tpf;
     80     }
     81 
     82     public void update() {
     83         tpf = (getTime() - previousTime) * (1.0f / TIMER_RESOLUTION);
     84         fps = 1.0f / tpf;
     85         previousTime = getTime();
     86     }
     87 
     88     public void reset() {
     89         startTime = System.nanoTime();
     90         previousTime = getTime();
     91     }
     92 }
     93