maintaining an event queue for passing events to the engine thread from the main SDL thread

git-svn-id: svn://anubis/anaglym/trunk@79 99a6e188-d820-4881-8870-2d33a10e2619

Engine.cc

@@ -28,7 +28,6 @@ Engine::Engine(const string & path)
     m_up[0] = 0;
     m_up[1] = 0;
     m_up[2] = 1;
-    m_drawing = false;
     m_autoPhysics = true;
 
     size_t pos = path.find_last_of("\\/");
@@ -215,7 +214,6 @@ int Engine::setCamera(lua_State * L)
 
 void Engine::update()
 {
-    m_drawing = true;
     if (m_autoPhysics)
         doPhysics();
     lua_getfield(m_luaState, LUA_GLOBALSINDEX, "update");
@@ -229,7 +227,6 @@ void Engine::update()
     {
         lua_pop(m_luaState, 1);
     }
-    m_drawing = false;
 }
 
 void Engine::doPhysics()

Engine.h

@@ -60,6 +60,7 @@ class Engine
         void drawObjects();
         void setAutoPhysics(bool autoPhysics) { m_autoPhysics = autoPhysics; }
         bool getAutoPhysics() { return m_autoPhysics; }
+        void update();
 
         /* lua services */
         int startFrame(lua_State * L);
@@ -69,7 +70,6 @@ class Engine
     protected:
         void registerLibraries();
         bool fileExists(const std::string & path);
-        void update();
         Object * createObject(bool is_static, GLuint display_list,
                 float scale = 1.0f)
         {
@@ -85,7 +85,6 @@ class Engine
         GLdouble    m_eye[3];
         GLdouble    m_center[3];
         GLdouble    m_up[3];
-        bool        m_drawing;
         bool        m_autoPhysics;
 };
 

anaglym.cc

@@ -6,14 +6,29 @@
 #include <stdlib.h>                 /* exit() */
 #include <iostream>
 #include <string>
+#include <queue>
 using namespace std;
 
+enum EventType { EVENT_UPDATE };
+
+typedef struct
+{
+    EventType   type;
+} Event;
+
 static void usage();
 static void mainloop();
+static void update();
+static void addEvent(const Event & event);
 static Uint32 updateCallback(Uint32 interval, void * param);
 
 static bool lastDrawCompleted;
+static bool engine_running;
 static SDL_Event userEvent;
+static SDL_cond * event_condition;
+static SDL_mutex * event_mutex;
+static SDL_mutex * event_queue_mutex;
+static queue<Event> event_queue;
 Uint32 g_ticks;
 
 static void usage()
@@ -22,6 +37,21 @@ static void usage()
     exit(42);
 }
 
+static int engine_thread(void * param)
+{
+    const char * program = (const char *) param;
+    if (g_engine->load(program))
+    {
+        for (;;)
+        {
+            SDL_mutexP(event_mutex);
+            SDL_CondWait(event_condition, event_mutex);
+        }
+    }
+    engine_running = false;
+    return 0;
+}
+
 int main(int argc, char * argv[])
 {
     const char * program = NULL;
@@ -53,9 +83,13 @@ int main(int argc, char * argv[])
     }
 
     lastDrawCompleted = true;
+    engine_running = true;
     /* setup SDL update event */
     userEvent.type = SDL_USEREVENT;
     userEvent.user.code = 0;
+    event_condition = SDL_CreateCond();
+    event_mutex = SDL_CreateMutex();
+    event_queue_mutex = SDL_CreateMutex();
 
     Video video;
 #if 0
@@ -66,12 +100,12 @@ int main(int argc, char * argv[])
 #endif
 
     g_engine = new Engine(argv[0]);
-    if (g_engine->load(program))
+    SDL_CreateThread(engine_thread, (void *) program);
-    {
-        mainloop();
-    }
-    delete g_engine;
 
+    mainloop();
+
+    SDL_DestroyCond(event_condition);
+    delete g_engine;
     video.stop();
 
     return 0;
@@ -94,6 +128,8 @@ static void mainloop()
 
     while (SDL_WaitEvent(&event))
     {
+        if (!engine_running)
+            goto RET;
         switch (event.type)
         {
             case SDL_KEYDOWN:
@@ -108,7 +144,7 @@ static void mainloop()
             case SDL_USEREVENT:
                 if (event.user.code == 0)
                 {
-                    /* TODO: update */
+                    update();
                 }
                 break;
         }
@@ -117,3 +153,17 @@ RET:
     ;
 }
 
+static void update()
+{
+    Event update_event;
+    update_event.type = EVENT_UPDATE;
+    addEvent(update_event);
+}
+
+static void addEvent(const Event & event)
+{
+    SDL_mutexP(event_queue_mutex);
+    event_queue.push(event);
+    SDL_mutexV(event_queue_mutex);
+    SDL_CondSignal(event_condition);
+}