diff --git a/src/d_main.c b/src/d_main.c
index f29fdd22497eeed4954beaf3af57f3dbee43342d..0931944fe3297a3d78c50b5307870c1c5845d7e2 100644
--- a/src/d_main.c
+++ b/src/d_main.c
@@ -702,8 +702,8 @@ void D_SRB2Loop(void)
boolean interp = false;
boolean doDisplay = false;
- precise_t frameTime = 0;
- int frameElapsed = 0;
+ double frameTime = 0.0;
+ double frameElapsed = 0.0;
if (dedicated)
server = true;
@@ -755,8 +755,8 @@ void D_SRB2Loop(void)
for (;;)
{
- frameTime = I_GetPreciseTime();
- frameElapsed = 0;
+ frameTime = I_GetFrameTime();
+ frameElapsed = 0.0;
if (lastwipetic)
{
@@ -903,7 +903,7 @@ void D_SRB2Loop(void)
SCR_CalculateFPS();
// Fully completed frame made, handle frame cap delay.
- frameElapsed = I_PreciseToMicros(I_GetPreciseTime() - frameTime);
+ frameElapsed = I_GetFrameTime() - frameTime;
if (!singletics)
{
diff --git a/src/i_system.h b/src/i_system.h
index f813135cefaab9b488ddc85a279160b732f60d34..a6f4ea70feb521d88a6df24d71a698fafdb7d285 100644
--- a/src/i_system.h
+++ b/src/i_system.h
@@ -42,11 +42,11 @@ extern UINT8 keyboard_started;
*/
UINT32 I_GetFreeMem(UINT32 *total);
-/** \brief Called by D_SRB2Loop, returns current time in tics.
+/** \brief Called by D_SRB2Loop, returns current time in game tics.
*/
tic_t I_GetTime(void);
-/** \brief Get the current time in tics including fractions.
+/** \brief Get the current time in game tics, including fractions.
*/
float I_GetTimeFrac(void);
@@ -58,6 +58,10 @@ precise_t I_GetPreciseTime(void);
*/
int I_PreciseToMicros(precise_t d);
+/** \brief Get the current time in rendering tics, including fractions.
+*/
+double I_GetFrameTime(void);
+
/** \brief Sleeps by the value of cv_sleep
\return void
@@ -68,7 +72,7 @@ void I_Sleep(void);
\return void
*/
-boolean I_FrameCapSleep(const int elapsed);
+boolean I_FrameCapSleep(const double elapsed);
/** \brief Get events
diff --git a/src/sdl/i_system.c b/src/sdl/i_system.c
index 428186f307dd81fbf88969fb4538177c6859ed24..21b262207ab093a204e745850141762899a00d38 100644
--- a/src/sdl/i_system.c
+++ b/src/sdl/i_system.c
@@ -2187,6 +2187,58 @@ int I_PreciseToMicros(precise_t d)
return (int)(UINT64)(d / (timer_frequency / 1000000.0));
}
+//
+// I_GetFrameTime
+// returns time in 1/fpscap second tics
+//
+
+static UINT32 frame_rate;
+
+static double frame_frequency;
+static UINT64 frame_epoch;
+static double elapsed_frames;
+
+static void I_InitFrameTime(const UINT64 now, const UINT32 cap)
+{
+ frame_rate = cap;
+ frame_epoch = now;
+
+ //elapsed_frames = 0.0;
+
+ if (frame_rate == 0)
+ {
+ // Shouldn't be used, but just in case...?
+ frame_frequency = 1.0;
+ return;
+ }
+
+ frame_frequency = timer_frequency / (double)frame_rate;
+}
+
+double I_GetFrameTime(void)
+{
+ const UINT64 now = SDL_GetPerformanceCounter();
+ const UINT32 cap = R_GetFramerateCap();
+
+ if (cap != frame_rate)
+ {
+ I_InitFrameTime(now, cap);
+ }
+
+ if (frame_rate == 0)
+ {
+ // Always advance a frame.
+ elapsed_frames += 1.0;
+ }
+ else
+ {
+ elapsed_frames += (now - frame_epoch) / frame_frequency;
+ }
+
+ frame_epoch = now; // moving epoch
+ return elapsed_frames;
+}
+
//
// I_StartupTimer
//
@@ -2197,6 +2249,9 @@ void I_StartupTimer(void)
tic_frequency = timer_frequency / (double)NEWTICRATE;
elapsed_tics = 0.0;
+
+ I_InitFrameTime(tic_epoch, R_GetFramerateCap());
+ elapsed_frames = 0.0;
}
//
@@ -2213,69 +2268,66 @@ void I_Sleep(void)
// I_FrameCapSleep
// Sleeps for a variable amount of time, depending on how much time the last frame took.
//
-boolean I_FrameCapSleep(const int elapsed)
+boolean I_FrameCapSleep(const double elapsed)
{
- const INT64 delayGranularity = 2000;
- // I picked 2ms as it's what GZDoom uses before it stops trying to sleep,
- // but maybe other values might work better.
+ // SDL_Delay(1) gives me a range of around 1.95ms to 2.05ms.
+ // Has a bit extra to be totally safe.
+ const double delayGranularity = 2.1;
- const UINT32 capFrames = R_GetFramerateCap();
- int capMicros = 0;
+ double capMS = 0.0;
+ double elapsedMS = 0.0;
+ double waitMS = 0.0;
- if (capFrames == 0)
+ if (frame_rate == 0)
{
// We don't want to cap.
return false;
}
- capMicros = 1000000 / capFrames;
+ capMS = 1000.0 / frame_rate; // Time of 1 frame, in milliseconds
+ elapsedMS = elapsed * capMS; // Convert elapsed from frame time to milliseconds.
+ waitMS = (capMS - elapsedMS); // How many MS to delay by.
- if (elapsed < capMicros)
+ if (waitMS <= 0.0)
{
- const INT64 error = capMicros / 40;
- // 2.5% ... How much we might expect the framerate to flucuate.
- // No exact logic behind this number, simply tried stuff until the framerate
- // reached the cap 300 more often and only overshot it occasionally.
+ // Too small of a wait, don't delay.
+ return false;
+ }
- INT64 wait = (capMicros - elapsed) - error;
+ while (waitMS > 0.0)
+ {
+ double sleepStart = I_GetFrameTime();
+ double sleepEnd = sleepStart;
+ double sleepElaspedMS = 0.0;
- while (wait > 0)
+ if (waitMS > delayGranularity && cv_sleep.value != -1)
{
- precise_t sleepStart = I_GetPreciseTime();
- precise_t sleepEnd = sleepStart;
- int sleepElasped = 0;
+ // Wait 1ms at a time (on default settings)
+ // until we're close enough.
+ SDL_Delay(cv_sleep.value);
- if (wait > delayGranularity && cv_sleep.value != -1)
- {
- // Wait 1ms at a time (on default settings)
- // until we're close enough.
- SDL_Delay(cv_sleep.value);
+ sleepEnd = I_GetFrameTime();
+ sleepElaspedMS = (sleepEnd - sleepStart) * capMS;
+ }
+ else
+ {
+ // When we have an extremely fine wait,
+ // we do this to spin-lock the remaining time.
- sleepEnd = I_GetPreciseTime();
- sleepElasped = I_PreciseToMicros(sleepEnd - sleepStart);
- }
- else
+ while (sleepElaspedMS < waitMS)
{
- // 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);
- }
-
- break;
+ sleepEnd = I_GetFrameTime();
+ sleepElaspedMS = (sleepEnd - sleepStart) * capMS;
}
- wait -= sleepElasped;
+ break;
}
- // We took our nap.
- return true;
+ waitMS -= sleepElaspedMS;
}
- // We're lagging behind.
- return false;
+ // We took our nap.
+ return true;
}
#ifdef NEWSIGNALHANDLER