src/core/main.c

   1 /*!@file
   2   \brief   engine entry
   3   \details initializes necessary subsystems before invoking the preloader,
   4            which loads initial game data, before finally invoking the
   5            main loop gameloop(void)
   6   \author  K
   7   \date    2016
   8 ------------------------------------------------------------------------------*/
   9 #ifdef __EMSCRIPTEN__
  10 /* Web Environment */
  11 #define main em_main
  12 #include <SDL_ttf.h>
  13 #include <emscripten/emscripten.h>
  14 #else
  15 /* Traditional Environment */
  16 #ifdef __Win32
  17 #include <windows.h>
  18 #endif //__Win32
  19 #include <SDL2/SDL_ttf.h>
  20 #endif
  21 /* ENVIRONMENT-AGNOSTIC DEFINES */
  22 #include <SDL2/SDL.h>
  23 #include <SDL2/SDL_image.h>
  24 #include <stdint.h>
  25 #include <setjmp.h>
  26 #include <stdio.h>
  27 #define TRIGGERS quit_trigger
  28 #include <core/trigger.h>
  29 #include <core/engine.h>
  30
  31 /* private functions */
  32 static int main_init(void);
  33
  34 /* exposed functions */
  35 void main_loop(void);
  36
  37 /* unexposed externs *
  38 extern int         state_init(void);
  39 extern void        state_tick(uint32_t delta_ticks);
  40 extern const char* state_get_error(void);
  41 extern void        state_quit(void);
  42 extern void        state_handle_event(SDL_Event event);
  43 extern int         io_init(void);
  44 extern const char* io_get_error(void);
  45 extern void        io_quit(void);*/
  46 /* main jump buffer */
  47 jmp_buf jmp_main;
  48
  49 /* Main Entry
  50
  51    initializes subsystems and calls main_loop(void)
  52
  53    main sets a jump buffer for its primary switch, which may be jumped to
  54    at any time.  Jumping with a 0 return value is equivalent to calling
  55    setjmp directly, which initializes the system and begins the main loop.
  56    Jumping with any other value will process one of the directives associated
  57    with the exit codes in core.h
  58 *******************************************************************************/
  59 #ifdef __EMSCRIPTEN__
  60 #define main_loop()\
  61   emscripten_set_main_loop(main_loop,0,0);\
  62   TRIGGER_SET(quit_trigger, emscripten_cancel_main_loop);\
  63   return 0;
  64 int
  65 main (int argc, char** argv)
  66 { switch(setjmp(jmp_main))
  67     { case 0:
  68         if (main_init())
  69           return -1;
  70         main_loop();
  71       case EXIT_GRACEFUL:
  72         break;
  73       default:
  74       case EXIT_PANIC:
  75         //dump some debug info
  76         break;
  77     }
  78   TRIGGER(quit_trigger);
  79   return 0;
  80 }
  81
  82 #undef main_loop
  83 #endif //EMSCRIPTEN
  84
  85 /** subsystem initializer
  86     Calling main_init() bootstraps the system, and may be called multiple
  87     times to cause a system-wide reboot.
  88   @return 0 if successful, -1 SDL, -2 IMG, -3 TTF, -4 STATE.
  89   SDL and logging is available after this is called
  90  ******************************************************************************/
  91 #define INIT(_subsys_id,_cond,_errorstring,_quit)\
  92   if (_cond)\
  93     { fprintf(stderr, #_cond " failed: %s\n", _errorstring());\
  94       return -_subsys_id;\
  95     }\
  96   TRIGGER_SET(quit_trigger, _quit)
  97
  98 #define SDL_FLAGS SDL_INIT_EVERYTHING & ~(SDL_INIT_TIMER | SDL_INIT_HAPTIC)
  99
 100 static
 101 int
 102 main_init()
 103 { static char bInitialized = 0;
 104   if (bInitialized++)
 105     { TRIGGER(quit_trigger);
 106       SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Resetting [%d]\n",
 107                   bInitialized);
 108     }
 109
 110   INIT(1, SDL_Init(SDL_FLAGS) < 0, SDL_GetError, SDL_Quit);
 111   INIT(2, IMG_Init(IMG_INIT_PNG) != IMG_INIT_PNG, IMG_GetError, IMG_Quit);
 112   INIT(3, TTF_Init() == -1, TTF_GetError, TTF_Quit);
 113
 114 /*TODO:
 115   INIT(4, io_init(), io_get_error, io_quit);
 116   INIT(5, state_init(), state_get_error, state_quit);
 117 */
 118
 119   SDL_Log("Initialization Complete.");
 120   return 0;
 121 }
 122
 123 /** main loop.
 124  *******************************************************************************/
 125 void
 126 main_loop()
 127 { static uint32_t main_loop_last_ticks = 0;
 128   SDL_Event event;
 129   uint32_t delta_ticks;
 130
 131 #ifdef LOOP_YIELD_OPTIONAL
 132 loop:
 133 #endif
 134   /* Poll events (user/system inputs) */
 135   while (SDL_PollEvent(&event))
 136     //state_handle_event(&event);
 137     ;
 138
 139   /* change in time since last loop */
 140   delta_ticks = SDL_GetTicks() - main_loop_last_ticks;
 141
 142   /* handle breakpoints (long pause likely a breakpoint) */
 143   if (delta_ticks > 1000)
 144     { SDL_LogWarn(SDL_LOG_CATEGORY_SYSTEM, "Recovering from long pause.");
 145       delta_ticks = TARGET_DT;
 146     }
 147
 148   /* tick the state manager forward by the change in time */
 149   //state_tick(delta_ticks);
 150   main_loop_last_ticks = SDL_GetTicks();
 151
 152   /* render the scene to backbuffer */
 153 ////TODO: state_tick(delta_ticks);
 154   /* swap in the backbuffer for display */
 155 ////TODO: state_render();
 156
 157 #ifdef LOOP_YIELD_OPTIONAL
 158 #define DIV_UP(x,y) ((x + (y / 2)) / y)
 159
 160   /* cap the framerate if we're handling the loop mechanism directly, but only
 161      yield if we have a substantial portion of time to yield (1/10th of the
 162      target delta) */
 163   delta_ticks = SDL_GetTicks() - main_loop_last_ticks;
 164   if ((delta_ticks + DIV_UP(TARGET_DT, 10)) < TARGET_DT)
 165     SDL_Delay(TARGET_DT - delta_ticks);
 166
 167   goto loop;
 168 #endif
 169 }
 170