From 1bff73aea0b9fab06a2d4dca0c69e69f1737a87e Mon Sep 17 00:00:00 2001
From: Sally Coolatta <tehrealsalt@gmail.com>
Date: Mon, 18 Apr 2022 17:18:31 -0400
Subject: [PATCH] Improve the framerate limiter's timing for extreme stable FPS
---
src/d_main.c | 32 ++++++++++----------------
src/sdl/i_system.c | 57 +++++++++++++++++++++++++++-------------------
2 files changed, 46 insertions(+), 43 deletions(-)
diff --git a/src/d_main.c b/src/d_main.c
index 731710a9c..470ec4fb7 100644
--- a/src/d_main.c
+++ b/src/d_main.c
@@ -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();
}
}
diff --git a/src/sdl/i_system.c b/src/sdl/i_system.c
index 6b9b11327..b3db8b455 100644
--- a/src/sdl/i_system.c
+++ b/src/sdl/i_system.c
@@ -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.
-
- // 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);
+ while (wait > 0)
+ {
+ precise_t sleepStart = I_GetPreciseTime();
+ precise_t sleepEnd = sleepStart;
+ int sleepElasped = 0;
+
+ 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;
}
--
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