annotate src/com/aurellem/capture/IsoTimer.java @ 54:6484a820e27d

wrote main documentation.
author Robert McIntyre <rlm@mit.edu>
date Sat, 03 Dec 2011 19:15:43 -0600
parents edaa7e7806e4
children afc437f637bd
rev   line source
rlm@4 1 package com.aurellem.capture;
rlm@4 2
rlm@4 3 import com.jme3.system.Timer;
rlm@4 4
rlm@54 5 /**
rlm@54 6 * A standard JME3 application that extends SimpleApplication or
rlm@54 7 * Application tries as hard as it can to keep in sync with
rlm@54 8 * user-time. If a ball is rolling at 1 game-mile per game-hour in the
rlm@54 9 * game, and you wait for one user-hour as measured by the clock on
rlm@54 10 * your wall, then the ball should have traveled exactly one
rlm@54 11 * game-mile. In order to keep sync with the real world, the game
rlm@54 12 * throttles its physics engine and graphics display. If the
rlm@54 13 * computations involved in running the game are too intense, then the
rlm@54 14 * game will first skip frames, then sacrifice physics accuracy. If
rlm@54 15 * there are particularly demanding computations, then you may only get
rlm@54 16 * 1 fps, and the ball may tunnel through the floor or obstacles due
rlm@54 17 * to inaccurate physics simulation, but after the end of one
rlm@54 18 * user-hour, that ball will have traveled one game-mile.
rlm@54 19 *
rlm@54 20 * When we're recording video or audio, we don't care if the game-time
rlm@54 21 * syncs with user-time, but instead whether the time in the recorded
rlm@54 22 * video (video-time) syncs with user-time. To continue the analogy,
rlm@54 23 * if we recorded the ball rolling at 1 game-mile per game-hour and
rlm@54 24 * watched the video later, we would want to see 30 fps video of the
rlm@54 25 * ball rolling at 1 video-mile per user-hour. It doesn't matter how
rlm@54 26 * much user-time it took to simulate that hour of game-time to make
rlm@54 27 * the high-quality recording. If an Application uses this IsoTimer
rlm@54 28 * instead of the normal one, we can be sure that every call to
rlm@54 29 * simpleUpdate, for example, corresponds to exactly (1 / fps) seconds
rlm@54 30 * of game-time. This let's us record perfect video and audio even on
rlm@54 31 * a slow computer.
rlm@54 32 *
rlm@54 33 * @author Robert McIntyre
rlm@54 34 *
rlm@54 35 */
rlm@54 36
rlm@4 37 public class IsoTimer extends Timer {
rlm@4 38
rlm@4 39 private float framerate;
rlm@4 40 private int ticks;
rlm@4 41
rlm@4 42 public IsoTimer(float framerate){
rlm@4 43 this.framerate = framerate;
rlm@54 44 this.ticks = 0;
rlm@54 45 }
rlm@4 46
rlm@4 47 public long getTime() {
rlm@54 48 return (long) (this.ticks / this.framerate);
rlm@54 49 }
rlm@4 50
rlm@4 51 public long getResolution() {
rlm@54 52 return 1000000000L;
rlm@54 53 }
rlm@4 54
rlm@4 55 public float getFrameRate() {
rlm@54 56 return this.framerate;
rlm@54 57 }
rlm@4 58
rlm@4 59 public float getTimePerFrame() {
rlm@54 60 return (float) (1.0f / this.framerate);
rlm@54 61 }
rlm@4 62
rlm@4 63 public void update() {this.ticks++;}
rlm@4 64
rlm@4 65 public void reset() {this.ticks = 0;}
rlm@4 66
rlm@4 67 }