Added some performance boosting framerate regulation

Makefile

@@ -4,7 +4,11 @@ PROJECT=treewars
 CXX=g++
 CXXFLAGS=-DDEBUG -g `sdl-config --cflags`
 LDFLAGS=`sdl-config --libs`
-OBJECTS=main.o drawutils.o mathutils.o graph.o gamedata.o  mainevent.o gamestate.o game.o titlescreen.o
+OBJECTS=\
+main.o \
+drawutils.o mathutils.o timer.o \
+graph.o gamedata.o \
+mainevent.o gamestate.o game.o titlescreen.o
 
 all: $(PROJECT)
 

game.cpp

@@ -31,8 +31,7 @@ bool Game::init()
 	return false;
     }
 
-    init_done = true;
-    return true;
+    return GameState::init();
 }
 
 

gamestate.cpp

@@ -1,5 +1,7 @@
 #include "gamestate.h"
 
+unsigned int GameState::FPS = 60;
+
 GameState::GameState(stack<GameState*>* state_stack, SDL_Surface* display)
 {
     this->state_stack = state_stack;
@@ -8,13 +10,29 @@ GameState::GameState(stack<GameState*>* state_stack, SDL_Surface* display)
 }
 
 
+bool GameState::init()
+{
+    timer.start();
+    init_done = true;
+    return true;
+}
+
+
 void GameState::execute() throw(StateExit)
 {
+    timer.start();
+
     SDL_Event event;
     while(SDL_PollEvent(&event))
 	handle_event(&event);
     iterate();
     render();
+
+    // Let's avoid using *too* much of the CPU...
+    if (timer.get_ticks() < 1000/FPS)
+    {
+	SDL_Delay((1000/FPS) - timer.get_ticks());
+    }
 }
 
 

gamestate.h

@@ -7,6 +7,7 @@
 #define _GAME_STATE_H_
 
 #include "mainevent.h"
+#include "timer.h"
 #include <SDL.h>
 #include <exception>
 #include <stack>
@@ -22,10 +23,11 @@ class GameState : public MainEvent
     GameState(stack<GameState*>* state_stack, SDL_Surface* display);
     virtual ~GameState() {}
 
-    virtual bool init() = 0;
     void execute() throw(StateExit);
     bool initted() { return init_done;}
 
+    virtual bool init();
+
   protected:
     virtual void iterate() = 0;
     virtual void render() = 0;
@@ -35,6 +37,9 @@ class GameState : public MainEvent
     stack<GameState*>* state_stack;
     SDL_Surface* display;
     bool init_done;
+    Timer timer;
+
+    static unsigned int FPS;
 };
 
 

timer.cpp

@@ -0,0 +1,26 @@
+#include "timer.h"
+
+Timer::Timer()
+{
+    init_ticks = 0;
+    current_ticks = 0;
+}
+
+
+void Timer::start()
+{
+    init_ticks = SDL_GetTicks();
+    current_ticks = init_ticks;
+}
+
+
+int Timer::get_ticks()
+{
+    // The odd case that we overflow...
+    // If this happens, we basically reset the timer. This isn't the most
+    // elegant solution, but it's the best one I see. Nothing should rely
+    // on this timer for super-precision as a result
+    if (current_ticks < init_ticks) init_ticks = current_ticks;
+
+    return current_ticks - init_ticks;
+}

timer.h

@@ -0,0 +1,23 @@
+/* A wrapper around the SDL_GetTicks() function, to add more
+ * convenient and intelligent functionality
+ */
+
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+#include <SDL.h>
+
+class Timer
+{
+ public:
+    Timer();
+
+    void start();
+    int get_ticks();
+
+ private:
+    int init_ticks;
+    int current_ticks;
+};
+
+#endif

titlescreen.cpp

@@ -42,8 +42,7 @@ bool TitleScreen::init()
 
     DrawUtils::transpare(title_banner);
 
-    init_done = true;
-    return true;
+    return GameState::init();
 }