From 05990dc5a009088c84fb5350dcf07eec4f826df7 Mon Sep 17 00:00:00 2001
From: Matt Mullins <mokomull@gmail.com>
Date: Sun, 12 Jul 2009 17:42:24 -0500
Subject: [PATCH] Modified the game loop to use events posted by a timer

---
 Game.cpp  | 76 ++++++++++++++++++++++++++++++++++++++++++++-------------------
 Game.h    |  4 ++++
 Level.cpp |  3 ---
 3 files changed, 57 insertions(+), 26 deletions(-)

diff --git a/Game.cpp b/Game.cpp
index e2679b2..db7596a 100644
--- a/Game.cpp
+++ b/Game.cpp
@@ -1,18 +1,21 @@
 #include "Game.h"
 #include "fns.h"
 #include <string>
+#include <iostream>
+
+const Uint32 Game::waitTime = 30; /* ms */
 
 Game::Game() : mCurrentLevel(0), mScreen(0)
 {
 	// Initialize SDL 
-	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) < 0) {
 		printf ("Couldn't initialize SDL: %s\n", SDL_GetError ());
 		exit (1);
 	}
 	atexit (SDL_Quit);
 
 	// Set 800x600 video mode
-	mScreen = SDL_SetVideoMode(640, 468, 32, SDL_SWSURFACE);
+	mScreen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
 	if (!mScreen) {
 		printf ("Couldn't set video mode: %s\n", SDL_GetError ());
 		exit (2);
@@ -56,35 +59,62 @@ void Game::run()
 {
 	bool done = false;
 
+	SDL_TimerID timer = SDL_AddTimer(waitTime, timerCallback, NULL);
+	if (!timer) {
+		std::cerr << "Timer creation failed" << std::endl;
+		return;
+	}
+
 	// Game Loop
 	while (!done) {
 		// This will let us track events
 		SDL_Event event;
 
-		// We fill 'event' with the first event in the event queue
-		while (SDL_PollEvent(&event)) {
-			switch (event.type) {
-			// If the event is a click on the close button in the top
-			// right corner of the window, we kill the application
-			case SDL_QUIT:
-				done = 1;
-				break;
+		// Wait for an event to occur
+		if (0 == SDL_WaitEvent(&event)) {
+			break;
+		}
 
-			// If our event reports a key being pressed down
-			// we process it
-			case SDL_KEYDOWN: {
-				Uint8 *keys = SDL_GetKeyState(NULL);
-				if (keys[SDLK_ESCAPE]) {
-					done = 1;
-					break;
-				}
-			}
-			default: /* fallthrough if the key wasn't escape */
-				getCurrentLevel()->postEvent(event);
+		switch (event.type) {
+		// If the event is a click on the close button in the top
+		// right corner of the window, we kill the application
+		case SDL_QUIT:
+			done = 1;
+			break;
+
+		case SDL_USEREVENT:
+			getCurrentLevel()->drawScene();
+			break;
+
+		// If our event reports a key being pressed down
+		// we process it
+		case SDL_KEYDOWN: {
+			Uint8 *keys = SDL_GetKeyState(NULL);
+			if (keys[SDLK_ESCAPE]) {
+				done = 1;
 				break;
 			}
 		}
-
-		getCurrentLevel()->drawScene();
+		default: /* fallthrough if the key wasn't escape */
+			getCurrentLevel()->postEvent(event);
+			break;
+		}
 	}
+
+	SDL_RemoveTimer(timer);
+}
+
+Uint32 Game::timerCallback(Uint32 interval, void* data)
+{
+	SDL_Event event;
+	SDL_UserEvent uevent = {
+		SDL_USEREVENT, /* type */
+		0, /* code */
+		0, /* data1 */
+		0 }; /* data2 */
+	event.user = uevent;
+
+	SDL_PushEvent(&event);
+
+	return interval;
 }
diff --git a/Game.h b/Game.h
index ae01b02..e8185a0 100644
--- a/Game.h
+++ b/Game.h
@@ -35,6 +35,8 @@ public:
 	void run();
 	
 private:
+	static const Uint32 waitTime;
+
 	int mCurrentLevel; /**< current index */
 	std::vector<Level*> mLevels;
 	SDL_Surface *mScreen;
@@ -42,6 +44,8 @@ private:
 	void addLevel(Level level);
 	void removeLevel(std::string levelName);
 	void loadLevel(std::string levelName);
+
+	static Uint32 timerCallback(Uint32 interval, void* data);
 };
 
 #endif
diff --git a/Level.cpp b/Level.cpp
index 6b78004..3ee28be 100644
--- a/Level.cpp
+++ b/Level.cpp
@@ -79,9 +79,6 @@ void Level::drawScene()
     
     // Flip the working image buffer with the mScreen buffer
     SDL_Flip (mScreen);
-    
-    // Add a little pause...
-    SDL_Delay (1);
 }
 
 void Level::DrawSprites()
-- 
2.11.0