Replace “accumulator >= step” by “accumulator > step” in FlxGame.as

[FlixelCommunityBot]

Issue #200 by: ghost

krix@7fbc822

More explanation: http://forums.flixel.org/index.php/topic,5072.0.html

[FlixelCommunityBot]

Comment by: avoxgames

There is a danger that at the first time a call of the function step() may be skipped (when you set high framerate, for example FlxG.flashFramerate = 90) and _state.draw() will fail.

[IQAndreas]

For anyone digging into this issue, I have found these two articles which should help:

• Flixel's Internal Structure and Performance Tips
• Deterministic Delta-tee in JS Games

[IQAndreas]

I have been trying to dig into this issue myself, and although I now understand the idea behind the deterministic delta-tee, I'm having some difficulty juggling those variables in my head, but I think I have a solution.

This is how the original code looks (with Krix's addition which seems to also be recommended by the article mentioned earlier):

_accumulator += elapsedMS;
if(_accumulator > _maxAccumulation)
    _accumulator = _maxAccumulation;
while(_accumulator >= _step)
{
    step();
    _accumulator -= _step;
}

And this is my idea, which would ensure that step() is always run at least once, whether the framereate is high or low, or is catching up after some lag.

_accumulator += elapsedMS;
if(_accumulator > _maxAccumulation)
    _accumulator = _maxAccumulation;
do
{
    step();
    _accumulator -= _step;
} while(_accumulator >= _step);  // <-- would this now be "greater than" or "greater than or equals"?

However, I'm very uncertain whether or not I'm thinking along the right lines, so I would like someone else to check me on this.