X-Git-Url: https://git.dogcows.com/gitweb?p=chaz%2Fyoink;a=blobdiff_plain;f=src%2Fengine.cc;h=7284799343a1f144d136ac65705f94c0ff54ad67;hp=3e40361a3213f73c220d2ced348931c9dfd4e8cb;hb=838bc00015eb7f583c7cf4b3b1007697bf047da1;hpb=79b5f738f2e38acb60cda7e09f54802933a17105

diff --git a/src/engine.cc b/src/engine.cc
index 3e40361..7284799 100644
--- a/src/engine.cc
+++ b/src/engine.cc
@@ -46,12 +46,13 @@
 namespace dc {
 
 
-class engine_impl
+class engine::engine_impl
 {
 public:
 	engine_impl(const std::string& name, int argc, char* argv[],
-			const std::string& configFile, engine* outer) : config(argc, argv),
-			interface(outer)
+			const std::string& configFile, engine* outer) :
+		config(argc, argv),
+		interface(outer)
 	{
 		if (SDL_Init(SDL_INIT_EVERYTHING | SDL_INIT_EVENTTHREAD) != 0)
 		{
@@ -69,15 +70,16 @@ public:
 		screen = video_ptr(new video(name));
 		screen->makeActive();
 
-		timestep = 0.01;
-		config.get("engine.timestep", timestep);
+		double ts = 0.01;
+		config.get("engine.timestep", ts);
+		timestep = scalar(ts);
 
 		long maxfps = 40;
-		config.get("engine.maxfps", maxfps);
+		config.getNumber("video.maxfps", maxfps);
 		drawrate = 1.0 / scalar(maxfps);
 
 		printfps = false;
-		config.get("engine.printfps", printfps);
+		config.get("video.printfps", printfps);
 	}
 
 	~engine_impl()
@@ -90,6 +92,13 @@ public:
 	}
 
 
+	/**
+	 * The main loop.  This just calls dispatchEvents(), update(), and draw()
+	 * over and over again.  The timing of the update and draw are decoupled.
+	 * The actual frame rate is also calculated here.  This function will return
+	 * with a value of 0 if the member variable running becomes true.
+	 */
+
 	int run()
 	{
 		scalar ticksNow = ticks();
@@ -99,42 +108,47 @@ public:
 		scalar nextFPSUpdate = ticksNow + 1.0;
 
 		scalar totalTime = 0.0;
-		scalar accumulator = 0.0;
+		scalar deltaTime = 0.0;
+		scalar accumulator = timestep;
 
-		fps = 0.0;
-		int frameAccum = 0.0;
+		fps = 0;
+		int frameAccum = 0;
 
 		running = true;
 		do
 		{
-			dispatchEvents();
-
 			scalar newTicks = ticks();
-			accumulator += newTicks - ticksNow;
+			deltaTime = newTicks - ticksNow;
 			ticksNow = newTicks;
 
-			if (ticksNow >= nextStep)
+			if (deltaTime >= 0.25) deltaTime = 0.25;
+			accumulator += deltaTime;
+
+			while (accumulator >= timestep)
 			{
+				dispatchEvents();
 				interface->update(totalTime, timestep);
 
 				totalTime += timestep;
 				accumulator -= timestep;
 
 				nextStep += timestep;
-				if (ticksNow >= nextStep) nextStep = ticksNow + timestep;
 			}
 
 			if (ticksNow >= nextDraw)
 			{
 				frameAccum++;
 
-				if (ticksNow >= nextFPSUpdate)
+				if (ticksNow >= nextFPSUpdate) // determine the actual fps
 				{
-					fps = frameAccum;// + (ticksNow - nextFPSUpdate) / 1.0;
+					fps = frameAccum;
 					frameAccum = 0;
 
 					nextFPSUpdate += 1.0;
-					if (ticksNow >= nextFPSUpdate) nextFPSUpdate = ticksNow + 1.0;
+					if (ticksNow >= nextFPSUpdate)
+					{
+						nextFPSUpdate = ticksNow + 1.0;
+					}
 
 					if (printfps)
 					{
@@ -146,25 +160,32 @@ public:
 				screen->swap();
 
 				nextDraw += drawrate;
-				if (ticksNow >= nextDraw) nextDraw = ticksNow + drawrate;
+				if (ticksNow >= nextDraw)
+				{
+					// we missed some scheduled draws, so reset the schedule
+					nextDraw = ticksNow + drawrate;
+				}
 			}
 
+			// be a good citizen and give back what you don't need
 			sleep(std::min(nextStep, nextDraw), true);
 		}
 		while (running);
+
+		return 0;
 	}
 
 
 	void dispatchEvents()
 	{
-		SDL_Event event;
+		SDL_Event e;
 
-		while (FE_PollEvent(&event) == 1)
+		while (FE_PollEvent(&e) == 1)
 		{
-			switch (event.type)
+			switch (e.type)
 			{
 				case SDL_KEYDOWN:
-					if (event.key.keysym.sym == SDLK_ESCAPE &&
+					if (e.key.keysym.sym == SDLK_ESCAPE &&
 							(SDL_GetModState() & KMOD_CTRL) )
 					{
 					   exit(0);
@@ -172,11 +193,11 @@ public:
 					break;
 
 				case SDL_VIDEORESIZE:
-					screen->resize(event.resize.w, event.resize.h);
+					screen->resize(e.resize.w, e.resize.h);
 					break;
 			}
 
-			interface->dispatchEvent(event);
+			interface->handleEvent(e);
 		}
 	}
 
@@ -196,16 +217,17 @@ public:
 	engine* interface;
 };
 
+
 engine::engine(const std::string& name, int argc, char* argv[],
-		const std::string& configFile)
-		: impl(new engine_impl(name, argc, argv, configFile, this)) {}
+		const std::string& configFile) :
+	impl(new engine::engine_impl(name, argc, argv, configFile, this)) {}
 
 engine::~engine() {}
 
 
 int engine::run()
 {
-	impl->run();
+	return impl->run();
 }
 
 void engine::stop()
@@ -248,8 +270,10 @@ long engine::getFPS()
 
 void engine::update(scalar t, scalar dt) {}
 void engine::draw(scalar alpha) {}
-void engine::dispatchEvent(const SDL_Event& event) {}
+void engine::handleEvent(const SDL_Event& e) {}
 
 
 } // namespace dc
 
+/** vim: set ts=4 sw=4 tw=80: *************************************************/
+