@Override
    public void reset() {
        lastFrameDiff = 0;
        lastFPS = 0;
        lastTPF = 0;

        // init to -1 to indicate this is a new timer.
        oldTime = -1;
        //reset time
        startTime = Sys.getTime();

        tpf = new long[TIMER_SMOOTHNESS];
        smoothIndex = TIMER_SMOOTHNESS - 1;
        invTimerRezSmooth = ( 1f / (LWJGL_TIMER_RES * TIMER_SMOOTHNESS));

        // set tpf... -1 values will not be used for calculating the average in update()
        for ( int i = tpf.length; --i >= 0; ) {
            tpf[i] = -1;
        }
    }
Constructor builds a <code>Timer</code> object. All values will be
initialized to its default values.
jme3-lwjgl/src/main/java/com/jme3/system/lwjgl/LwjglSmoothingTimer.java