📚 Doxygen: added codebase overview page

doc/doxygen/Doxyfile.conf.in

@@ -762,6 +762,7 @@ WARN_LOGFILE           =
 # Note: If this tag is empty the current directory is searched.
 
 INPUT                  = @DOXYGEN_SOURCE_DIR@/MainPage.h \
+                         @DOXYGEN_SOURCE_DIR@/Overview.h \
                          @PROJECT_SOURCE_DIR@/source
 
 # This tag can be used to specify the character encoding of the source files

doc/doxygen/Overview.h

@@ -0,0 +1,22 @@
+/*!
+ * @page Codebase overview
+ *
+ * # The application
+ * 
+ * Rigs of Rods is a monolithic C++ program with it's own main input/rendering loop.
+ * The entry point is a standard main() function which performs all initialization, message processing and cleanup.
+ * 
+ * # Input handling
+ * Inputs are received via OIS library's listener mechanism.
+ * Class RoR::AppContext is the sole listener for all inputs and serves as a dispatcher between various subsystems.
+ * Gameplay inputs are defined by enum events and handled by InputEngine. RoR::InputEngine also reads input configuration files '*.map', the default being 'input.map'.
+ *
+ * # Rendering
+ * Graphical output is done via OGRE 3D rendering engine (not to be confused with game engine).
+ * Startup is done by RoR::AppContext::SetUpRendering().
+ * Window events are handled by RoR::AppContext via OGRE's OgreBites::WindowEventListener. Note Ogre::FrameListener interface is not used, we roll our own rendering loop in main().
+ * 
+ * 
+ *
+ *
+ */