refactor game speed to provide a constant frame rate

doc/scripts/config.html

@@ -1205,21 +1205,20 @@ Sets the resolution of the video display, valid options are 640x480, 800x600, 10
 <a name="SetVideoSyncSpeed"></a>
 <h3>SetVideoSyncSpeed(speed)</h3>
 
-Sets the video sync speed for the game. 100 is equivilent to 30 frames/second.  200
+Sets the video render speed for the game. 30 means 30 frames/second. 60 means 60 frames/second. Default is the native monitor refresh rate.
-is equivilent to 60 frames/second.
 
 <dl>
 <dt>speed</dt>
-<dd>The speed to set the game to as described, 100 is default</dd>
+<dd>The speed to set the game to as described, default is the monitor refresh rate.</dd>
 <dt><i>RETURNS</i></dt>
 <dd>Nothing</dd>
 </dl>
 
-<h4>Exmaple</h4>
+<h4>Example</h4>
 
 <pre>
     -- Set Speed to 60 frames/second
-    SetVideoSyncSpeed(200)
+    SetVideoSyncSpeed(60)
 </pre>
 
 <a name="ShowEnergySelectedOnly"></a>

src/editor/editloop.cpp

@@ -2105,7 +2105,7 @@ void EditorMainLoop()
 		bool start = true;
 
 		while (Editor.Running) {
-			if (FrameCounter % FRAMES_PER_SECOND == 0) {
+			if (FrameCounter % CYCLES_PER_SECOND == 0) {
 				if (UpdateMinimap) {
 					UI.Minimap.Update();
 					UpdateMinimap = false;

src/game/game.cpp

@@ -635,14 +635,14 @@ bool GetGamePaused()
 }
 
 /**
-**  Set the game speed
+**  Set the game speed in range 0 .. 100
 **
 **  @param speed  New game speed.
 */
 void SetGameSpeed(int speed)
 {
 	if (GameCycle == 0 || FastForwardCycle < GameCycle) {
-		VideoSyncSpeed = speed * 100 / CYCLES_PER_SECOND;
+		CyclesPerSecond = (static_cast<double>(speed) / 100) * CYCLES_PER_SECOND + static_cast<double>(CYCLES_PER_SECOND) / 3;
 		SetVideoSync();
 	}
 }
@@ -654,7 +654,7 @@ void SetGameSpeed(int speed)
 */
 int GetGameSpeed()
 {
-	return CYCLES_PER_SECOND * VideoSyncSpeed / 100;
+	return ((static_cast<double>(CyclesPerSecond) - static_cast<double>(CYCLES_PER_SECOND) / 3) / CYCLES_PER_SECOND) * 100;
 }
 
 /*----------------------------------------------------------------------------

src/include/interface.h

@@ -207,8 +207,8 @@ extern bool GamePaused;
 extern bool GameObserve;
 /// Flag telling if the game is in establishing mode
 extern bool GameEstablishing;
-/// Flag telling not to advance to the next game cycle
+/// Counter of how many game cycles to skip for each rendered frame
-extern char SkipGameCycle;
+extern double SkipGameCycle;
 /// Invincibility cheat
 extern bool GodMode;
 /// Whether the map is the only thing displayed or not

src/include/settings.h

@@ -65,8 +65,6 @@ constexpr unsigned short UpgradeMax = 2048;                /// How many upgrades
 constexpr unsigned char MAX_RACES = 8;
 constexpr unsigned char PlayerNumNeutral = PlayerMax - 1;  /// this is the neutral player slot
 
-/// Frames per second to display (original 30-40)
-constexpr unsigned char FRAMES_PER_SECOND = 30; // 1/30s
 /// Game cycles per second to simulate (original 30-40)
 constexpr unsigned char CYCLES_PER_SECOND = 30;  // 1/30s 0.33ms
 

src/include/video.h

@@ -405,15 +405,12 @@ public:
 extern CVideo Video;
 
 /**
-**  Video synchronization speed. Synchronization time in percent.
+**  Target CyclesPerSecond that are simulated. The default is CYCLES_PER_SECOND.
-**  If =0, video framerate is not synchronized. 100 is exact
-**  CYCLES_PER_SECOND (30). Game will try to redraw screen within
-**  intervals of VideoSyncSpeed, not more, not less.
 **  @see CYCLES_PER_SECOND
 */
-extern int VideoSyncSpeed;
+extern int CyclesPerSecond;
 
-extern int SkipFrames;
+extern double SkipCycles;
 
 /// Fullscreen or windowed set from commandline.
 extern char VideoForceFullScreen;
@@ -421,6 +418,9 @@ extern char VideoForceFullScreen;
 /// Next frame ticks
 extern double NextFrameTicks;
 
+/// Target refresh rate for renderer
+extern int RefreshRate;
+
 /// Counts frames
 extern unsigned long FrameCounter;
 

src/map/minimap.cpp

@@ -370,7 +370,7 @@ void CMinimap::Update()
 {
 	static int red_phase;
 
-	int red_phase_changed = red_phase != (int)((FrameCounter / FRAMES_PER_SECOND) & 1);
+	int red_phase_changed = red_phase != (int)((FrameCounter / CYCLES_PER_SECOND) & 1);
 	if (red_phase_changed) {
 		red_phase = !red_phase;
 	}

src/network/network.cpp

@@ -1148,11 +1148,10 @@ static void CheckPlayerThatTimeOut(int hostIndex)
 	if (!lastFrame) {
 		return;
 	}
-	const int framesPerSecond = FRAMES_PER_SECOND * VideoSyncSpeed / 100;
+	const int secs = (FrameCounter - lastFrame) / CyclesPerSecond;
-	const int secs = (FrameCounter - lastFrame) / framesPerSecond;
 	// FIXME: display a menu while we wait
 	const int timeoutInS = CNetworkParameter::Instance.timeoutInS;
-	if (3 <= secs && secs < timeoutInS && FrameCounter % framesPerSecond == 0) {
+	if (3 <= secs && secs < timeoutInS && FrameCounter % CyclesPerSecond == 0) {
 		SetMessage(_("Waiting for player \"%s\": %d:%02d"), Hosts[hostIndex].PlyName,
 				   (timeoutInS - secs) / 60, (timeoutInS - secs) % 60);
 	}

src/stratagus/mainloop.cpp

@@ -110,15 +110,15 @@ void DoScrollArea(int state, bool fast, bool isKeyboard)
 	vp = UI.SelectedViewport;
 
 	if (fast) {
-		stepx = (int)(speed * vp->MapWidth / 2 * PixelTileSize.x * FRAMES_PER_SECOND / 4);
+		stepx = (int)(speed * vp->MapWidth / 2 * PixelTileSize.x * CYCLES_PER_SECOND / 4);
-		stepy = (int)(speed * vp->MapHeight / 2 * PixelTileSize.y * FRAMES_PER_SECOND / 4);
+		stepy = (int)(speed * vp->MapHeight / 2 * PixelTileSize.y * CYCLES_PER_SECOND / 4);
 	} else {// dynamic: let these variables increase up to fast..
 		// FIXME: pixels per second should be configurable
-		stepx = (int)(speed * PixelTileSize.x * FRAMES_PER_SECOND / 4);
+		stepx = (int)(speed * PixelTileSize.x * CYCLES_PER_SECOND / 4);
-		stepy = (int)(speed * PixelTileSize.y * FRAMES_PER_SECOND / 4);
+		stepy = (int)(speed * PixelTileSize.y * CYCLES_PER_SECOND / 4);
 	}
 	if ((state & (ScrollLeft | ScrollRight)) && (state & (ScrollLeft | ScrollRight)) != (ScrollLeft | ScrollRight)) {
-		stepx = stepx * 100 * 100 / VideoSyncSpeed / FRAMES_PER_SECOND / (SkipFrames + 1);
+		stepx = stepx * 3;
 		remx += stepx - (stepx / 100) * 100;
 		stepx /= 100;
 		if (remx > 100) {
@@ -129,7 +129,7 @@ void DoScrollArea(int state, bool fast, bool isKeyboard)
 		stepx = 0;
 	}
 	if ((state & (ScrollUp | ScrollDown)) && (state & (ScrollUp | ScrollDown)) != (ScrollUp | ScrollDown)) {
-		stepy = stepy * 100 * 100 / VideoSyncSpeed / FRAMES_PER_SECOND / (SkipFrames + 1);
+		stepy = stepy * 3;
 		remy += stepy - (stepy / 100) * 100;
 		stepy /= 100;
 		if (remy > 100) {
@@ -255,7 +255,7 @@ static void GameLogicLoop()
 	//
 	// Game logic part
 	//
-	if (!GamePaused && NetworkInSync && !SkipGameCycle) {
+	if (!GamePaused && NetworkInSync && SkipGameCycle < 1) {
 		SinglePlayerReplayEachCycle();
 		++GameCycle;
 		MultiPlayerReplayEachCycle();
@@ -333,11 +333,6 @@ static void GameLogicLoop()
 #endif
 }
 
-//#define REALVIDEO
-#ifdef REALVIDEO
-static	int RealVideoSyncSpeed;
-#endif
-
 static void DisplayLoop()
 {
 	/* update only if viewmode changed */
@@ -359,12 +354,6 @@ static void DisplayLoop()
 
 	ColorCycle();
 
-#ifdef REALVIDEO
-	if (FastForwardCycle > GameCycle && RealVideoSyncSpeed != VideoSyncSpeed) {
-		RealVideoSyncSpeed = VideoSyncSpeed;
-		VideoSyncSpeed = 3000;
-	}
-#endif
 	if (FastForwardCycle <= GameCycle || GameCycle <= 10 || !(GameCycle & CallPeriod::cEvery256th)) {
 		//FIXME: this might be better placed somewhere at front of the
 		// program, as we now still have a game on the background and
@@ -375,11 +364,6 @@ static void DisplayLoop()
 		UpdateDisplay();
 		RealizeVideoMemory();
 	}
-#ifdef REALVIDEO
-	if (FastForwardCycle == GameCycle) {
-		VideoSyncSpeed = RealVideoSyncSpeed;
-	}
-#endif
 }
 
 static void SingleGameLoop()
@@ -416,10 +400,6 @@ void GameMainLoop()
 
 	CParticleManager::init();
 
-#ifdef REALVIDEO
-	RealVideoSyncSpeed = VideoSyncSpeed;
-#endif
-
 	CclCommand("if (GameStarting ~= nil) then GameStarting() end");
 
 	long ticks = SDL_GetTicks();
@@ -440,11 +420,6 @@ void GameMainLoop()
 		return;
 	}
 
-#ifdef REALVIDEO
-	if (FastForwardCycle > GameCycle) {
-		VideoSyncSpeed = RealVideoSyncSpeed;
-	}
-#endif
 	NetworkQuitGame();
 	EndReplayLog();
 

src/stratagus/stratagus.cpp

@@ -590,7 +590,7 @@ void ParseCommandLine(int argc, char **argv, Parameters &parameters)
 				AiSleepCycles = atoi(optarg);
 				continue;
 			case 'S':
-				VideoSyncSpeed = atoi(optarg);
+				RefreshRate = atoi(optarg);
 				continue;
 			case 'u':
 				if (!strcmp(optarg, "userhome")) {

src/ui/interface.cpp

@@ -84,7 +84,7 @@ bool GameRunning;                    /// Current running state
 bool GamePaused;                     /// Current pause state
 bool GameObserve;                    /// Observe mode
 bool GameEstablishing;               /// Game establishing mode
-char SkipGameCycle;                  /// Skip the next game cycle
+double SkipGameCycle;                /// Skip the next n game cycles
 char BigMapMode;                     /// Show only the map
 enum _iface_state_ InterfaceState;   /// Current interface state
 bool GodMode;                        /// Invincibility cheat
@@ -349,7 +349,7 @@ static void UiIncreaseGameSpeed()
 	if (FastForwardCycle >= GameCycle) {
 		return;
 	}
-	VideoSyncSpeed += 10;
+	CyclesPerSecond++;
 	SetVideoSync();
 	UI.StatusLine.Set(_("Faster"));
 }
@@ -362,12 +362,8 @@ static void UiDecreaseGameSpeed()
 	if (FastForwardCycle >= GameCycle) {
 		return;
 	}
-	if (VideoSyncSpeed <= 10) {
+	if (CyclesPerSecond > 1) {
-		if (VideoSyncSpeed > 1) {
+		--CyclesPerSecond;
-			--VideoSyncSpeed;
-		}
-	} else {
-		VideoSyncSpeed -= 10;
 	}
 	SetVideoSync();
 	UI.StatusLine.Set(_("Slower"));
@@ -381,7 +377,7 @@ static void UiSetDefaultGameSpeed()
 	if (FastForwardCycle >= GameCycle) {
 		return;
 	}
-	VideoSyncSpeed = 100;
+	CyclesPerSecond = CYCLES_PER_SECOND;
 	SetVideoSync();
 	UI.StatusLine.Set(_("Set default game speed"));
 }

src/ui/mainscr.cpp

@@ -1151,7 +1151,7 @@ static void InfoPanel_draw_no_selection()
 			y += 16;
 			label.Draw(x, y,  _("Cycle:"));
 			label.Draw(x + 48, y, GameCycle);
-			label.Draw(x + 110, y, CYCLES_PER_SECOND * VideoSyncSpeed / 100);
+			label.Draw(x + 110, y, CyclesPerSecond);
 			y += 20;
 
 			std::string nc;

src/video/sdl.cpp

@@ -99,7 +99,11 @@ static int NumRects;
 static std::map<int, std::string> Key2Str;
 static std::map<std::string, int> Str2Key;
 
-double FrameTicks;     /// Frame length in ms
+/// Frame length in ms
+static double FrameTicks;
+
+/// Target refresh rate for renderer
+int RefreshRate = 0;
 
 const EventCallback *Callbacks;
 
@@ -116,29 +120,47 @@ uint32_t SDL_CUSTOM_KEY_UP;
 --  Sync
 ----------------------------------------------------------------------------*/
 
+static int GetRefreshRate()
+{
+	if (!RefreshRate) {
+		int displayCount = SDL_GetNumVideoDisplays();
+		SDL_DisplayMode mode;
+		for (int i = 0; i < displayCount; i++) {
+			SDL_GetDesktopDisplayMode(0, &mode);
+			if (mode.refresh_rate > RefreshRate) {
+				RefreshRate = mode.refresh_rate;
+			}
+		}
+		if (!RefreshRate) {
+			RefreshRate = 60;
+		}
+	}
+	return RefreshRate;
+}
+
 /**
 **  Initialise video sync.
 **  Calculate the length of video frame and any simulation skips.
 **
-**  @see VideoSyncSpeed @see SkipFrames @see FrameTicks
+**  @see CyclesPerSecond @see SkipCycles @see SkipFrames @see FrameTicks
 */
 void SetVideoSync()
 {
-	double ms;
+	int fps = GetRefreshRate();
-
+	int nativeFps = fps;
-	if (VideoSyncSpeed) {
+	if (fps < CyclesPerSecond) {
-		ms = (1000.0 * 1000.0 / CYCLES_PER_SECOND) / VideoSyncSpeed;
+		fprintf(stdout, "WARNING: Game speed is faster than monitor refresh rate.\n");
+		FrameTicks = 1000.0 / CyclesPerSecond;
+		SDL_GL_SetSwapInterval(0); // disable vsync, so we can run faster than the refresh
 	} else {
-		ms = (double)INT_MAX;
+		FrameTicks = 1000.0 / fps;
+		if (SDL_GL_SetSwapInterval(-1) < 0) { // try to set adaptive vsync
+			SDL_GL_SetSwapInterval(1); // if it failed, set vsync
+		}
 	}
-	SkipFrames = ms / 400;
+	SkipCycles = (static_cast<double>(fps) / CyclesPerSecond) - 1;
-	while (SkipFrames && ms / SkipFrames < 200) {
-		--SkipFrames;
-	}
-	ms /= SkipFrames + 1;
 
-	FrameTicks = ms / 10;
+	DebugPrint("native fps: %d, render frame skip: %d, game cycle skip: %f\n" _C_ nativeFps _C_ Preference.FrameSkip _C_ SkipCycles);
-	DebugPrint("frames %d - %5.2fms\n" _C_ SkipFrames _C_ ms / 10);
 }
 
 /*----------------------------------------------------------------------------
@@ -785,8 +807,10 @@ void WaitEventsOneFrame()
 	}
 	handleInput(NULL);
 
-	if (!SkipGameCycle--) {
+	if (SkipGameCycle < 0) {
-		SkipGameCycle = SkipFrames;
+		SkipGameCycle += SkipCycles;
+	} else {
+		SkipGameCycle--;
 	}
 }
 
@@ -795,21 +819,10 @@ void WaitEventsOneFrame()
 */
 
 static Uint32 LastTick = 0;
-static int RefreshRate = 0;
 
 static void RenderBenchmarkOverlay()
 {
-	if (!RefreshRate) {
+	int RefreshRate = GetRefreshRate();
-		int displayCount = SDL_GetNumVideoDisplays();
-		SDL_DisplayMode mode;
-		for (int i = 0; i < displayCount; i++) {
-			SDL_GetDesktopDisplayMode(0, &mode);
-			if (mode.refresh_rate > RefreshRate) {
-				RefreshRate = mode.refresh_rate;
-			}
-		}
-	}
-
 	// show a bar representing fps, where the entire bar is the max refresh rate of attached displays
 	Uint32 nextTick = SDL_GetTicks();
 	Uint32 frameTime = nextTick - LastTick;

src/video/video.cpp

@@ -168,8 +168,8 @@ int ClipY2;                          /// current clipping bottom right
 
 static std::vector<Clip> Clips;
 
-int VideoSyncSpeed = 100;            /// 0 disable interrupts
+int CyclesPerSecond = CYCLES_PER_SECOND;
-int SkipFrames;                      /// Skip this frames
+double SkipCycles;                      /// Skip this frames
 
 Uint32 ColorBlack;
 Uint32 ColorDarkGreen;
@@ -348,9 +348,10 @@ void DeInitVideo()
 */
 static int CclSetVideoSyncSpeed(lua_State *l)
 {
-	LuaCheckArgs(l, 1);
+       LuaCheckArgs(l, 1);
-	VideoSyncSpeed = LuaToNumber(l, 1);
+       RefreshRate = LuaToNumber(l, 1);
-	return 0;
+	   SetVideoSync();
+       return 0;
 }
 
 void VideoCclRegister()