#ifndef APP_H_
#define APP_H_
+extern long time_msec;
+extern int win_width, win_height;
extern bool opt_gear_wireframe;
+bool app_init();
+void app_cleanup();
+
+void app_display();
+void app_reshape(int x, int y);
+
+void app_keyboard(int key, bool pressed);
+void app_mouse_button(int bn, bool pressed, int x, int y);
+void app_mouse_motion(int x, int y);
+
+// the following functions are implemented by the backend (main.cc)
+void app_quit();
+void app_swap_buffers();
+
#endif // APP_H_