[.. upper level ..]

Tutorial 6

Our last ping-pong game from tutorial 5 uses fixed keyboard keys to move the player-rackets.
Here we add a system-menu, in which we have the possibility to change these keys.

We add a file menu.c with its menu.h.

• Step 1
  
  
  At first we show the modifications in the main-program and player-object.
  
• Step 1.1
  
  
  The individual game structure will get more elements:
  - a pointer to the system-menu structure
  - an integer containing the gamecontroller-/joystick-ID (or 0 = keyboard)
  
  Differences green-highlighted in main.h:

  /* individual game structure */
  struct game {
    struct vg3_window *wstruct;   /* window structure */
    int winw, winh;               /* size of window */
    struct vg3_ofunc *ofstruct;   /* common VgaGames3-object structure */
    struct vg3_quadtree *qdtr;    /* collision-quadtree */
    struct vg3_sysmenu *sysm;     /* system-menu structure */
    int jid;                      /* gamecontroller-/joystick-ID or 0 = keyboard */
    int key_up, key_down;         /* keyboard keys for moving the player-racket */
    struct vg3_nwclient *nwclnt;  /* network structure */
    int endgame;                  /* flag to end the game */
  };
  

• Step 1.2
  
  
  In the main-program we
  - we include the file menu.h
  - call the creation of the system-menu create_menu()
  - replace 0 with game->jid when defining the network keys
  - call the system-menu with VG3_sysmenu_exec() when pressing the escape-key
  - destroy the system-menu when cleaning up
  
  Differences green-highlighted in main.c:
  
  We include the file menu.h
  

  #include <vgagames3.h>
  #include "main.h"
  #include "menu.h"
  

  
  Call the creation of the system-menu create_menu()
  

    /* create collision-quadtree with size of window */
    rect.x = rect.y = 0;
    rect.w = game.winw;
    rect.h = game.winh;
    game.qdtr = VG3_coll_q_new(&rect, 0, 0);
    if (game.qdtr == NULL) { fprintf(stderr, "%s\n", VG3_error()); goto endgame; }
  
    /* define keyboard keys */
    game.key_up = VGAG3_KEY_UCURS;
    game.key_down = VGAG3_KEY_DCURS;
  
    /* create system-menu */
    create_menu(&game);
  
    game.nwclnt = NULL;
    game.endgame = 0;
  

  
  Replace 0 with game->jid when defining the network keys
  

      /* open network */
      game.nwclnt = VG3_nw_open(game.wstruct);
  
      /* define network-keys */
      VG3_nw_addkey(game.nwclnt, game.jid, game.key_up);
      VG3_nw_addkey(game.nwclnt, game.jid, game.key_down);
  
      /* connect to network-server with default port and name = hostname
       * and return own client-number,
       * we only want two players to connect
       */
  

  
  Call the system-menu with VG3_sysmenu_exec() when pressing the escape-key
  

      /* ALT+Q: exit */
      VG3_key_ispressed(game.wstruct, VGAG3_KEY_Q, VGAG3_IS_NEW_PRESSED)
        && VG3_key_ispressed(game.wstruct, VGAG3_KEY_LALT, VGAG3_IS_PRESSED)) { break; }
  
      /* Escape: system-menu */
      if (VG3_key_ispressed(game.wstruct, VGAG3_KEY_ESC, VGAG3_IS_NEW_PRESSED)) {
        if (VG3_sysmenu_exec(game.sysm)) { break; }
        change_nw_keys(&game);  /* eventually actualize network-keys */
      }
  
      /* clear window with halfdark blue background */
  

  
  Destroy the system-menu when cleaning up
  

    /* close network connection */
    VG3_nw_close(game.nwclnt);
  
    /* free system-menu */
    VG3_sysmenu_free(game.sysm);
  
  endgame:
    /* close window and exit */
  

• Step 1.3
  
  
  In the player-object we just replace the 0 with game->jid when checking the pressed keys.
  
  Differences green-highlighted in obj-player.c:

    /* +++ check for key-strokes and set moving direction +++ */
  
    gobj->ydelta = 0;
    if (VG3_nw_key_ispressed(game->nwclnt, gobj->clnr, game->jid, game->key_up, VGAG3_IS_PRESSED)) {
      gobj->ydelta = -100;  /* set moving upwards: full y-direction, no x-direction */
    }
    if (VG3_nw_key_ispressed(game->nwclnt, gobj->clnr, game->jid, game->key_down, VGAG3_IS_PRESSED)) {
      gobj->ydelta = 100;  /* set moving downwards: full y-direction, no x-direction */
    }
  
    /* +++ move player according to moving direction and check for collisions +++ */
  



• Step 2
  
  
  We add the file menu.c with its menu.h.
  
• Step 2.1
  
  
  menu.h:

  #ifndef MENU_H_
  #define MENU_H_
  
  void create_menu(struct game *);
  void change_nw_keys(struct game *);
  
  #endif /* MENU_H_ */
  

• Step 2.2
  
  
  Instead of dealing with real key-definitions (VGAG3_KEYS) we use an abstract enumeration (KEY_UP, KEY_DOWN).
  create_menu():
  We create a system-menu and insert an exit-menu, a volume-menu and a keyboard-menu.
  The keyboard-menu has submenus for each defined key, here we install two of them, where KEY_UP and KEY_DOWN refer to.
  change_nw_keys():
  When the system-menu was called we check for changed keys comparing the new ones with our saved previous.
  
  menu.c:

  #include <vgagames3.h>
  #include "main.h"
  
  void create_menu(struct game *);
  void change_nw_keys(struct game *);
  
  /* set enumeration for keyboard keys in struct game: key_up and key_down */
  enum { KEY_UP, KEY_DOWN };
  
  
  /* create system-menu */
  void
  create_menu(struct game *game)
  {
    struct vg3_text stxt;
    struct vg3_sysmenu_submenu *inputmenu, *submenu;
  
    game->sysm = VG3_sysmenu_new(game->wstruct, NULL, VG3_color_brightness(VGAG3_COLOR_GREEN, 50), VGAG3_COLOR_GREEN);
  
    /* insert exit-menu */
    VG3_sysmenu_simple_exitmenu(game->sysm, NULL, "Exit game");
  
    /* insert volume-menu with only main-, sound- and music-volume */
    VG3_sysmenu_simple_volumemenu(game->sysm, NULL, "Main volume", "Sound volume", NULL, NULL);
  
    /* insert a sub-menu for input-settings */
    VGAG3_TEXT_ATTRIBUTES_SET(&stxt, NULL, 0, 0, "Input settings");
    inputmenu = VG3_sysmenu_insert_menuentry(game->sysm, NULL, &stxt);
  
    /* insert keyboard-menu into input settings sub-menu */
    submenu = VG3_sysmenu_simple_keyboardmenu(game->sysm, inputmenu);
  
    /* add key-settings KEY_UP and KEY_DOWN to keyboard-menu */
    game->jid = 0;  /* keyboard */
    game->key_up = VGAG3_KEY_UCURS;
    game->key_down = VGAG3_KEY_DCURS;
    VG3_sysmenu_simple_keyboardentry(game->sysm, submenu, KEY_UP, "move upwards", game->key_up, "Upwards moving");
    VG3_sysmenu_simple_keyboardentry(game->sysm, submenu, KEY_DOWN, "move downwards", game->key_down, "Downwards moving");
  }
  
  
  /* if keyboard keys were changed, actualize network-structure */
  void
  change_nw_keys(struct game *game)
  {
    int keyidx;
  
    /* KEY_UP has been changed? */
    keyidx = VG3_sysmenu_getkeyval(game->sysm, game->jid, KEY_UP);  /* get actual key for KEY_UP */
    if (keyidx != game->key_up) {
      VG3_nw_changekey(game->nwclnt, game->jid, game->key_up, keyidx);  /* replace network-key */
      game->key_up = keyidx;
    }
  
    /* KEY_DOWN has been changed? */
    keyidx = VG3_sysmenu_getkeyval(game->sysm, game->jid, KEY_DOWN);  /* get actual key for KEY_DOWN */
    if (keyidx != game->key_down) {
      VG3_nw_changekey(game->nwclnt, game->jid, game->key_down, keyidx);  /* replace network-key */
      game->key_down = keyidx;
    }
  }
  



• Step 3
  
  
  Now we enhance our system-menu to replace the keyboard with a gamecontroller/joystick if one exits.
  
• Step 3.1
  
  
  create_menu():
  We check whether exactly one gamecontroller/joystick is connected,
  if yes, we use it instead of the keyboard.
  change_nw_keys():
  No changes needed.
  
  menu.c:

  #include <vgagames3.h>
  #include "main.h"
  
  void create_menu(struct game *);
  void change_nw_keys(struct game *);
  
  /* set enumeration for keyboard keys in struct game: key_up and key_down */
  enum { KEY_UP, KEY_DOWN };
  
  
  /* create system-menu */
  void
  create_menu(struct game *game)
  {
    struct vg3_text stxt;
    struct vg3_sysmenu_submenu *inputmenu, *submenu;
    int *fjid;
  
    game->sysm = VG3_sysmenu_new(game->wstruct, NULL, VG3_color_brightness(VGAG3_COLOR_GREEN, 50), VGAG3_COLOR_GREEN);
  
    /* insert exit-menu */
    VG3_sysmenu_simple_exitmenu(game->sysm, NULL, "Exit game");
  
    /* insert volume-menu with only main-, sound- and music-volume */
    VG3_sysmenu_simple_volumemenu(game->sysm, NULL, "Main volume", "Sound volume", NULL, NULL);
  
    /* insert a sub-menu for input-settings */
    VGAG3_TEXT_ATTRIBUTES_SET(&stxt, NULL, 0, 0, "Input settings");
    inputmenu = VG3_sysmenu_insert_menuentry(game->sysm, NULL, &stxt);
  
    /* get number of found gamecontrollers/joysticks */
    VG3_gamecontroller_getall(game->wstruct, &fjid);
    if (fjid[0] == 1) {  /* exactly one gamecontroller/joystick found */
      game->jid = fjid[1];
    } else {  /* no or more than one gamecontrollers/joysticks found: we use keyboard */
      game->jid = 0;
    }
    free(fjid);
  
    /* insert keyboard-menu or gamecontroller-/joystick-menu if exactly one is found */
    if (game->jid > 0) {  /* gamecontroller/joystick */
      struct vg3_gamecontroller gcs;
  
      /* insert gamecontroller-/joystick-menu into input settings sub-menu */
      submenu = VG3_sysmenu_simple_gcmenu(game->sysm, inputmenu);
  
      /* get information about connected gamecontroller/joystick */
      VG3_gamecontroller_getinfo(game->wstruct, game->jid, &gcs);
  
      /* add KEY_UP to gamecontroller-/joystick-menu */
      if (gcs.is_gamecontroller) {  /* gamecontroller */
        game->key_up = VGAG3_GC_AXIS_RIGHTY_UP;
      } else {  /* joystick */
        game->key_up = 1;  /* just an unknown key */
      }
      VG3_sysmenu_simple_gcentry(game->sysm, submenu, game->jid, KEY_UP, "move upwards", game->key_up, "Upwards moving");
  
      /* add KEY_DOWN to gamecontroller-/joystick-menu */
      if (gcs.is_gamecontroller) {  /* gamecontroller */
        game->key_down = VGAG3_GC_AXIS_RIGHTY_DOWN;
      } else {  /* joystick */
        game->key_down = 2;  /* just an unknown key */
      }
      VG3_sysmenu_simple_gcentry(game->sysm, submenu, game->jid, KEY_DOWN, "move downwards", game->key_down, "Downwards moving");
    } else {  /* keyboard */
      /* insert keyboard-menu into input settings sub-menu */
      submenu = VG3_sysmenu_simple_keyboardmenu(game->sysm, inputmenu);
  
      /* add key-settings KEY_UP and KEY_DOWN to keyboard-menu */
      game->key_up = VGAG3_KEY_UCURS;
      game->key_down = VGAG3_KEY_DCURS;
      VG3_sysmenu_simple_keyboardentry(game->sysm, submenu, KEY_UP, "move upwards", game->key_up, "Upwards moving");
      VG3_sysmenu_simple_keyboardentry(game->sysm, submenu, KEY_DOWN, "move downwards", game->key_down, "Downwards moving");
    }
  }
  
  
  /* if keyboard keys were changed, actualize network-structure */
  void
  change_nw_keys(struct game *game)
  {
    int keyidx;
  
    /* KEY_UP has been changed? */
    keyidx = VG3_sysmenu_getkeyval(game->sysm, game->jid, KEY_UP);  /* get actual key for KEY_UP */
    if (keyidx != game->key_up) {
      VG3_nw_changekey(game->nwclnt, game->jid, game->key_up, keyidx);  /* replace network-key */
      game->key_up = keyidx;
    }
  
    /* KEY_DOWN has been changed? */
    keyidx = VG3_sysmenu_getkeyval(game->sysm, game->jid, KEY_DOWN);  /* get actual key for KEY_DOWN */
    if (keyidx != game->key_down) {
      VG3_nw_changekey(game->nwclnt, game->jid, game->key_down, keyidx);  /* replace network-key */
      game->key_down = keyidx;
    }
  }
  



• Putting together
  
  
  See the files in example-games/tutorial6/


• Executing the system-menu
  
  
  

  Main menu
  

  Input menu
  

  Found gamecontrollers
  

  Setting for gamecontroller