Cleanup of main update calbacks

Clarify update and draw of rendering manager by using callbacks (instead of hidden calls in draw method).

RenderingManager.cpp

@@ -206,7 +206,7 @@ bool Rendering::init()
     // set application icon
     main_.setIcon("images/vimix_256x256.png");
     // additional window callbacks for main window
-//    glfwSetWindowRefreshCallback( main_.window(), WindowRefreshCallback );
+    glfwSetWindowRefreshCallback( main_.window(), WindowRefreshCallback );
     glfwSetDropCallback( main_.window(), Rendering::FileDropped);
 
     //
@@ -316,19 +316,13 @@ void Rendering::draw()
     // operate on main window context
     main_.makeCurrent();
 
-    // User Interface step 1
-    UserInterface::manager().NewFrame();
-
-    // Custom draw
+    // draw
     std::list<Rendering::RenderingCallback>::iterator iter;
     for (iter=draw_callbacks_.begin(); iter != draw_callbacks_.end(); ++iter)
     {
         (*iter)();
     }
 
-    // User Interface step 2
-    UserInterface::manager().Render();
-
     // perform screenshot if requested
     if (request_screenshot_) {
         // glfwMakeContextCurrent(main_window_);

main.cpp

@@ -40,11 +40,22 @@ extern "C"{
 #endif
 
 
+void prepare()
+{
+    Mixer::manager().update();
+    UserInterface::manager().NewFrame();
+}
+
 void drawScene()
 {
     Mixer::manager().draw();
 }
 
+void renderGUI()
+{
+    UserInterface::manager().Render();
+}
+
 int main(int argc, char *argv[])
 {
     // one extra argument is given
@@ -127,8 +138,10 @@ int main(int argc, char *argv[])
     gst_debug_set_active(FALSE);
 #endif
 
-    // draw the scene
-    Rendering::manager().pushFrontDrawCallback(drawScene);
+    // callbacks to draw
+    Rendering::manager().pushBackDrawCallback(prepare);
+    Rendering::manager().pushBackDrawCallback(drawScene);
+    Rendering::manager().pushBackDrawCallback(renderGUI);
 
     // show all windows
     Rendering::manager().show();
@@ -137,11 +150,7 @@ int main(int argc, char *argv[])
     /// Main LOOP
     ///
     while ( Rendering::manager().isActive() )
-    {
-        Mixer::manager().update();
-
         Rendering::manager().draw();
-    }
 
     ///
     /// UI TERMINATE