Thread runs faster on a faster processor... how to control Thread speed

Question

I have a thread that uses TimeUnit.MILLISECONDS.sleep(5);

Problem is when I load my app on a faster phone say with a snapdragon, it runs at lightning speed.

Is there a way to control this speed so processor speed is not an attributing factor?

Thanks!

Answer 1

He'res the class I wrote for this purpose. Use it by first calling start() and then sleepRequiredTime() in your gameloop. call getTimeSinceLastSleep() for elapsed time.

runsPrSecondHint will dictate your wanted FPS. I'm not sure this solution is perfect though, so any input from others is welcome.

package com.ngame.spacegame.utils;

public class ThreadSleepManager {

private int m_runsPrSecondHint;
private float m_maxAllowedSleepTime;
private boolean m_running;

private long m_startTime = 0;
private long m_lastSleepTime = 0;

private int[] m_lastRuntimes;
private int m_runtimeToWriteToIndex = 0;
private int m_averageSleepTime = 0;
private int m_timeSinceLastSleep = 0;

private static final int AVERAGE_POOL = 10;

public ThreadSleepManager( int runsPrSecondHint ) {
    m_runsPrSecondHint = runsPrSecondHint;

    m_maxAllowedSleepTime = 1000.0f / m_runsPrSecondHint;
    initLastRuntimes();
}

private void initLastRuntimes() {
    m_lastRuntimes = new int[AVERAGE_POOL];
    for ( int i : m_lastRuntimes ) {
        m_lastRuntimes[ i ] = (int)m_maxAllowedSleepTime; 
    }
}

public int getTimeSinceLastSleep() {
    return m_timeSinceLastSleep;
}

public int getAverageSleepTime() {
    return m_averageSleepTime;
}

public void start() {
    m_startTime = System.currentTimeMillis();
    m_lastSleepTime = m_startTime;
}

/**
 * Sleeps an optimal amount of time for trying 
 * to have the current thread calling run at m_runsPrSecondHint
 */
public void sleepRequiredTime() {
    assert( m_running == true );
    long currentTime = System.currentTimeMillis();
    m_timeSinceLastSleep = (int) (currentTime - m_lastSleepTime);

    // Update data used for average sleep time calculation
    m_lastRuntimes[ m_runtimeToWriteToIndex ] = m_timeSinceLastSleep;
    m_runtimeToWriteToIndex = ( m_runtimeToWriteToIndex + 1 ) % AVERAGE_POOL;

    // Sleep long enough for the average time since last sleep to stay as close as
    // possible to m_maxAllowedSleepTime
    m_averageSleepTime = calcAverageTimeSinceLastSleep();

    int timeToSleep = (int) (m_maxAllowedSleepTime - m_averageSleepTime);
    if( timeToSleep > 0 ) {
        try {
            Thread.sleep( timeToSleep );
        }
        catch( InterruptedException e ) {

        }
    }

    m_lastSleepTime = currentTime;
}

private int calcAverageTimeSinceLastSleep() {
    int sum_sleep_time = 0;

    for ( int runtime : m_lastRuntimes ) {
        sum_sleep_time += runtime; 
    }

    return sum_sleep_time / m_lastRuntimes.length;
}

}

Answer 2

You need to Fix Your Timestep!

http://gafferongames.com/game-physics/fix-your-timestep/

Answer 3

Instead of sleeping to regulate game speed, use the time elapsed per frame to give everything a consistent speed.

myObject.Move(elapsedTime*moveSpeed,0,0);

Something to that effect. No matter what speed the processor runs at or the framerate, the object would always move at the same speed. Make sure any movement or rotation that requires a specific speed uses the same idea.