From d5c916b724a6d2ad233a972b21b71fc4ed0772ca Mon Sep 17 00:00:00 2001
From: Tim Felgentreff <timfelgentreff@gmail.com>
Date: Tue, 26 Jul 2022 18:04:15 +0200
Subject: [PATCH] make frame skip a preference

good values are
 1 - render only even frames
 3 - render only frames divisble by 4 (i.e., only 25%)

anything higher is probably just choppy
---
 src/include/unit.h          |  2 ++
 src/stratagus/stratagus.cpp |  2 +-
 src/tolua/unit.pkg          |  2 ++
 src/video/sdl.cpp           | 22 +---------------------
 4 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/src/include/unit.h b/src/include/unit.h
index 72c48208e..af9b7de33 100644
--- a/src/include/unit.h
+++ b/src/include/unit.h
@@ -469,6 +469,8 @@ public:
 	bool HardwareCursor;    /// If true, uses the hardware to draw the cursor. Shaders do no longer apply to the cursor, but this way it's decoupled from the game refresh rate
 	bool SelectionRectangleIndicatesDamage; /// If true, the selection rectangle interpolates color to indicate damage
 
+	int FrameSkip;          /// Mask used to skip rendering frames (useful for slow renderers that keep up with the game logic, but not the rendering to screen like e.g. original Raspberry Pi)
+
 	int ShowOrders;			/// How many second show orders of unit on map.
 	int ShowNameDelay;		/// How many cycles need to wait until unit's name popup will appear.
 	int ShowNameTime;		/// How many cycles need to show unit's name popup.
diff --git a/src/stratagus/stratagus.cpp b/src/stratagus/stratagus.cpp
index 9748f71a5..b824c8064 100644
--- a/src/stratagus/stratagus.cpp
+++ b/src/stratagus/stratagus.cpp
@@ -405,7 +405,7 @@ void Exit(int err)
 	FreeButtonStyles();
 	FreeAllContainers();
 	freeGuichan();
-	fprintf(stdout, "Frames %lu, Slow frames %d = %ld%%\n",
+	fprintf(stdout, "Frames %lu, Slow frames %ld = %ld%%\n",
 			   FrameCounter, SlowFrameCounter,
 			   (SlowFrameCounter * 100) / (FrameCounter ? FrameCounter : 1));
 	lua_settop(Lua, 0);
diff --git a/src/tolua/unit.pkg b/src/tolua/unit.pkg
index a51535f21..c1946ed86 100644
--- a/src/tolua/unit.pkg
+++ b/src/tolua/unit.pkg
@@ -37,6 +37,8 @@ class CPreference
 	bool HardwareCursor;
 	bool SelectionRectangleIndicatesDamage;
 
+        unsigned int FrameSkip;
+
 	unsigned int ShowOrders;
 	unsigned int ShowNameDelay;
 	unsigned int ShowNameTime;
diff --git a/src/video/sdl.cpp b/src/video/sdl.cpp
index 7c8269d20..f956484a8 100644
--- a/src/video/sdl.cpp
+++ b/src/video/sdl.cpp
@@ -719,9 +719,6 @@ const EventCallback *GetCallbacks()
 	return Callbacks;
 }
 
-static int SkipFrameMask = 0;
-static unsigned long NextSlowFrameReaction = FRAMES_PER_SECOND * 10;
-
 /**
 **  Wait for interactive input event for one frame.
 **
@@ -741,23 +738,6 @@ void WaitEventsOneFrame()
 	Uint32 ticks = SDL_GetTicks();
 	if (ticks > NextFrameTicks) { // We are too slow :(
 		++SlowFrameCounter;
-		if (SlowFrameCounter > NextSlowFrameReaction) {
-			unsigned long pct = (SlowFrameCounter * 100) / (FrameCounter ? FrameCounter : 1);
-			if (pct >= 60) {
-				SkipFrameMask = 0b111;
-			} else if (pct >= 40) {
-				SkipFrameMask = 0b101;
-			} else if (pct >= 20) {
-				SkipFrameMask = 0b11;
-			} else if (pct >= 10) {
-				SkipFrameMask = 0b1;
-			}
-			NextSlowFrameReaction += FRAMES_PER_SECOND * 10;
-			fprintf(stdout, "WARNING WARNING WARNING\n"
-							"Frames %lu, Slow frames %d = %lu%%, starting to render only every %d%s frame.\n",
-							FrameCounter, SlowFrameCounter, pct, SkipFrameMask + 1, SkipFrameMask == 1 ? "nd" : "th");
-			fflush(stdout);
-		}
 	}
 
 	InputMouseTimeout(*GetCallbacks(), ticks);
@@ -855,7 +835,7 @@ void RealizeVideoMemory()
 	if (dummyRenderer) {
 		return;
 	}
-	if (FrameCounter & SkipFrameMask) {
+	if (Preference.FrameSkip && (FrameCounter & Preference.FrameSkip)) {
 		return;
 	}
 	if (NumRects) {