private void RunLoop()
{
/* Some platforms (i.e. Emscripten) don't support
* indefinite while loops, so instead we have to
* surrender control to the platform's main loop.
* -caleb
*/
if (FNAPlatform.NeedsPlatformMainLoop())
{
/* This breaks control flow and jumps
* directly into the platform main loop.
* Nothing below this call will be executed.
*/
FNAPlatform.RunPlatformMainLoop(this);
}
while (RunApplication)
{
FNAPlatform.PollEvents(
this,
ref currentAdapter,
textInputControlDown,
textInputControlRepeat,
ref textInputSuppress
);
Tick();
}
OnExiting(this, EventArgs.Empty);
}
public void RunOneFrame()
{
if (!hasInitialized)
{
DoInitialize();
gameTimer = Stopwatch.StartNew();
hasInitialized = true;
}
FNAPlatform.PollEvents(
this,
ref currentAdapter,
textInputControlDown,
textInputControlRepeat,
ref textInputSuppress
);
Tick();
}
public void Tick()
{
/* NOTE: This code is very sensitive and can break very badly,
* even with what looks like a safe change. Be sure to test
* any change fully in both the fixed and variable timestep
* modes across multiple devices and platforms.
*/
AdvanceElapsedTime();
if (IsFixedTimeStep)
{
/* If we are in fixed timestep, we want to wait until the next frame,
* but we don't want to oversleep. Requesting repeated 1ms sleeps and
* seeing how long we actually slept for lets us estimate the worst case
* sleep precision so we don't oversleep the next frame.
*/
while (accumulatedElapsedTime + worstCaseSleepPrecision < TargetElapsedTime)
{
System.Threading.Thread.Sleep(1);
TimeSpan timeAdvancedSinceSleeping = AdvanceElapsedTime();
UpdateEstimatedSleepPrecision(timeAdvancedSinceSleeping);
}
/* Now that we have slept into the sleep precision threshold, we need to wait
* for just a little bit longer until the target elapsed time has been reached.
* SpinWait(1) works by pausing the thread for very short intervals, so it is
* an efficient and time-accurate way to wait out the rest of the time.
*/
while (accumulatedElapsedTime < TargetElapsedTime)
{
System.Threading.Thread.SpinWait(1);
AdvanceElapsedTime();
}
}
// Now that we are going to perform an update, let's poll events.
FNAPlatform.PollEvents(
this,
ref currentAdapter,
textInputControlDown,
textInputControlRepeat,
ref textInputSuppress
);
// Do not allow any update to take longer than our maximum.
if (accumulatedElapsedTime > MaxElapsedTime)
{
accumulatedElapsedTime = MaxElapsedTime;
}
if (IsFixedTimeStep)
{
gameTime.ElapsedGameTime = TargetElapsedTime;
int stepCount = 0;
// Perform as many full fixed length time steps as we can.
while (accumulatedElapsedTime >= TargetElapsedTime)
{
gameTime.TotalGameTime += TargetElapsedTime;
accumulatedElapsedTime -= TargetElapsedTime;
stepCount += 1;
AssertNotDisposed();
Update(gameTime);
}
// Every update after the first accumulates lag
updateFrameLag += Math.Max(0, stepCount - 1);
/* If we think we are running slowly, wait
* until the lag clears before resetting it
*/
if (gameTime.IsRunningSlowly)
{
if (updateFrameLag == 0)
{
gameTime.IsRunningSlowly = false;
}
}
else if (updateFrameLag >= 5)
{
/* If we lag more than 5 frames,
* start thinking we are running slowly.
*/
gameTime.IsRunningSlowly = true;
}
/* Every time we just do one update and one draw,
* then we are not running slowly, so decrease the lag.
*/
if (stepCount == 1 && updateFrameLag > 0)
{
updateFrameLag -= 1;
}
/* Draw needs to know the total elapsed time
* that occured for the fixed length updates.
*/
gameTime.ElapsedGameTime = TimeSpan.FromTicks(TargetElapsedTime.Ticks * stepCount);
}
else
{
// Perform a single variable length update.
if (forceElapsedTimeToZero)
{
/* When ResetElapsedTime is called,
* Elapsed is forced to zero and
* Total is ignored entirely.
* -flibit
*/
gameTime.ElapsedGameTime = TimeSpan.Zero;
forceElapsedTimeToZero = false;
}
else
{
gameTime.ElapsedGameTime = accumulatedElapsedTime;
gameTime.TotalGameTime += gameTime.ElapsedGameTime;
}
accumulatedElapsedTime = TimeSpan.Zero;
AssertNotDisposed();
Update(gameTime);
}
// Draw unless the update suppressed it.
if (suppressDraw)
{
suppressDraw = false;
}
else
{
/* Draw/EndDraw should not be called if BeginDraw returns false.
* http://stackoverflow.com/questions/4054936/manual-control-over-when-to-redraw-the-screen/4057180#4057180
* http://stackoverflow.com/questions/4235439/xna-3-1-to-4-0-requires-constant-redraw-or-will-display-a-purple-screen
*/
if (BeginDraw())
{
Draw(gameTime);
EndDraw();
}
}
}
