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Improve the framerate limiter's timing for extreme stable FPS

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Sally Coolatta 2022-04-18 17:18:31 -04:00 committed by Eidolon
parent 66cc234be6
commit 685190fe40
2 changed files with 45 additions and 42 deletions
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32
src/d_main.c
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@ -804,25 +804,17 @@ void D_SRB2Loop(void)
doDisplay = false;
ticked = false;
frameCap = false;
if (interp)
{
frameCap = D_CheckFrameCap();
}
frameCap = D_CheckFrameCap();
// Moved to here from I_FinishUpdate.
// It doesn't track fades properly anymore by being here (might be easy fix),
// but it's a little more accurate for actual rendering when its here.
SCR_CalculateFPS();
if (!realtics && !singletics)
{
if (interp)
{
if (frameCap)
continue;
}
else
{
// Non-interp sleep
I_Sleep();
if (frameCap)
continue;
}
}
#ifdef HW3SOUND
@ -920,6 +912,11 @@ void D_SRB2Loop(void)
}
else
{
if (frameCap)
{
continue;
}
renderdeltatics = realtics * FRACUNIT;
rendertimefrac = FRACUNIT;
}
@ -943,11 +940,6 @@ void D_SRB2Loop(void)
#endif
LUA_Step();
// Moved to here from I_FinishUpdate.
// It doesn't track fades properly anymore by being here (might be easy fix),
// but it's a little more accurate for actual game logic when its here.
SCR_CalculateFPS();
}
}

55
src/sdl/i_system.c
View file

@ -2203,7 +2203,7 @@ void I_Sleep(void)
boolean I_CheckFrameCap(precise_t start, precise_t end)
{
UINT32 capFrames = R_GetFramerateCap();
const UINT32 capFrames = R_GetFramerateCap();
int capMicros = 0;
int elapsed;
@ -2219,31 +2219,42 @@ boolean I_CheckFrameCap(precise_t start, precise_t end)
if (elapsed < capMicros)
{
// Wait to draw the next frame.
UINT32 wait = ((capMicros - elapsed) / 1000);
if (cv_sleep.value > 1)
// Experimental variable delay code.
if (cv_sleep.value > 0)
{
// 1 is the default, and in non-interpolated mode is just the bare minimum wait.
// Since we're already adding some wait with an FPS cap, only apply when it's above 1.
wait += cv_sleep.value - 1;
}
const INT64 delayGranularity = 2000; // 2ms, I picked this as it's what GZDoom uses before it stops trying to sleep.
INT64 wait = (capMicros - elapsed);
// If the wait's greater than our granularity value,
// we'll just burn the couple extra cycles in the main loop
// in order to get to the next frame.
// This makes us get to the exact FPS cap more often.
while (wait > 0)
{
precise_t sleepStart = I_GetPreciseTime();
precise_t sleepEnd = sleepStart;
int sleepElasped = 0;
// Higher values have more wasted CPU cycles, but the in-game frame performance is better.
// 10ms is the average clock tick of most OS scheduling.
// 15ms is a little more than that, for leniency on slow machines. (This helps mine reach a stable 60, at least!)
// (https://www.libsdl.org/release/SDL-1.2.15/docs/html/sdldelay.html)
#define DELAY_GRANULARITY 15
if (wait >= DELAY_GRANULARITY)
{
SDL_Delay(wait);
if (wait > delayGranularity)
{
// Wait 1ms at a time (on default settings)
// until we're close enough.
SDL_Delay(cv_sleep.value);
sleepEnd = I_GetPreciseTime();
sleepElasped = I_PreciseToMicros(sleepEnd - sleepStart);
}
else
{
// When we have an extremely fine wait,
// we do this to spin-lock the remaining time.
while (sleepElasped < wait)
{
sleepEnd = I_GetPreciseTime();
sleepElasped = I_PreciseToMicros(sleepEnd - sleepStart);
}
}
wait -= sleepElasped;
}
}
#undef DELAY_GRANULARITY
return true;
}