[.. upper level ..]

Tutorial 2

We create a simple ping-pong game for one player.

Using the keys cursor-up and cursor-down we move the racket.
With space-key we change the color to monochrome and back.
With ALT+Q we exit the game.

When the ball hits a border or the racket a short sound is played.
On exit a game-over sound is played.

• Step 1
  
  
  We create a skeleton main function.
  Object related actions will be put to functions and later explained.
  For simplicity with passing parameters to the functions we declare all related variables globally.
• Step 1.1
  
  At first do initialisations.

  #include <vgagames3.h>
  
  /* for simplicity declare variables globally, which are shared with functions */
  static struct vg3_window *wstruct;  /* window struct */
  static int winw, winh;  /* size of window */
  static int audio_hit, audio_gameover;  /* audio descriptors */
  
  int main(int argc, char **argv) {
    int coldef;
  
    /* open window */
    wstruct = VG3_window_new(argv[0], VGAG3_VGAVERSION_LOW, VGAG3_WINSCALE_BESTSCALE);
    if (wstruct == NULL) { fprintf(stderr, "%s\n", VG3_error()); exit(1); }
  
    /* get the size of the window */
    VG3_window_getsize(wstruct, &winw, &winh);
  
    /* create objects */
    if (!create_objects()) { goto endgame; }
  
    /* set initial color definition for window */
    coldef = VGAG3_COLORDEF_DEFAULT;
  
    /* print infos */
    printf("\n");
    printf("Keys:\n");
    printf("- cursor up, cursor down: move\n");
    printf("- spacebar: color change\n");
    printf("- ALT+Q: exit\n");
  

• Step 1.2
  
  We create the game-loop.

    /* +++ game-loop +++ */
  
    VG3_discard_input(wstruct);
    for (;;) {
      if (VG3_inputevent_update(wstruct) > 0) { break; }
  
      /* ALT+Q: exit */
      if (VG3_key_ispressed(wstruct, VGAG3_KEY_Q, VGAG3_IS_NEW_PRESSED)
        && VG3_key_ispressed(wstruct, VGAG3_KEY_LALT, VGAG3_IS_PRESSED)) { break; }
  
      /* change color to monochrome and vice versa? */
      if (VG3_key_ispressed(wstruct, VGAG3_KEY_SPACE, VGAG3_IS_NEW_PRESSED)) {
        if (coldef == VGAG3_COLORDEF_DEFAULT) {
          coldef = VGAG3_COLORDEF_GREY;
        } else {
          coldef = VGAG3_COLORDEF_DEFAULT;
        }
        VG3_window_attributes(wstruct, NULL, NULL, coldef, NULL);
      }
  
      /* clear window with halfdark blue background */
      VG3_draw_clear(wstruct, NULL, VG3_color_brightness(VGAG3_COLOR_BLUE, 50));
  
      /* move objects and check for interaction with other objects (touching) */
      if (!move_objects()) { break; }
  
      /* draw objects onto the window */
      draw_objects();
  
      /* draw out window-contents */
      VG3_window_update(wstruct, 0, 0);
  
      /* sleep until 30 msec are gone for this game-loop */
      VG3_wait_time(30);
    }
    VG3_discard_input(wstruct);
  

• Step 1.3
  
  After the game-loop we do the cleaning up.

    /* +++ game over +++ */
  
    /* play gameover.wav and wait for finishing */
    VG3_audio_play(wstruct, audio_gameover, 0, 0);
    while (VG3_audio_isplaying(wstruct, audio_gameover)) { VG3_wait_time(100); }
  
    /* clean up */
    VG3_image_unload(wstruct, NULL);
    VG3_audio_unload(wstruct, VG3_audio_group(VGAG3_AUDIO_VOLUME_ALL));
  
  endgame:
    /* close window and exit */
    VG3_window_free(wstruct);
    exit(0);
  }
  



• Step 2
  
  
  Now we have to create the missing functions.
• Step 2.1
  
  At first we declare the rest of the global variables.
  
  The structure struct object will hold the informations we need for every object:
  - the element img contains the loaded image.
  - the element rect contains the position and size of the object, represented by the image.
  - the sub-elements of rect:
  - - x and y contain the coordinate of the left upper corner
  - - w and h contain the width and height
  
  The objects are:
  - obj_hborder_up: upper horizontal border
  - obj_hborder_down: lower horizontal border
  - obj_vborder: right vertical border
  - obj_ball: moving ball
  - obj_player: player's racket on the left
  
  The variables xball and yball will hold the direction of the moving ball.

  /* structure for objects: borders, ball, player */
  struct object {
    struct vg3_image *img; /* loaded image */
    struct vg3_rect rect;  /* position and size */
  };
  
  /* for simplicity declare variables globally, which are shared with functions */
  static struct vg3_window *wstruct;  /* window struct */
  static int winw, winh;  /* size of window */
  static struct object obj_hborder_up, obj_hborder_down, obj_vborder, obj_ball, obj_player;  /* objects */
  static int xball, yball;  /* moving direction of the ball */
  static int audio_hit, audio_gameover;  /* audio descriptors */
  
  /* static functions */
  static int create_objects(void);
  static int move_objects(void);
  static void draw_objects(void);
  

• Step 2.2
  
  The function create_objects().
  For each object the image is loaded and the initial position is set.

  /* create objects and load audio files */
  static int
  create_objects(void)
  {
    /* +++ create upper horizontal border object +++ */
  
    /* load image */
    obj_hborder_up.img = VG3_image_load(wstruct, "hborder.bmp", 0);
    if (obj_hborder_up.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_hborder_up.img, NULL, &obj_hborder_up.rect.w, &obj_hborder_up.rect.h);
    obj_hborder_up.rect.x = obj_hborder_up.rect.y = 0;
  
    /* +++ create lower horizontal border object +++ */
  
    /* load image */
    obj_hborder_down.img = VG3_image_load(wstruct, "hborder.bmp", 0);
    if (obj_hborder_down.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_hborder_down.img, NULL, &obj_hborder_down.rect.w, &obj_hborder_down.rect.h);
    obj_hborder_down.rect.x = 0;
    obj_hborder_down.rect.y = winh - obj_hborder_down.rect.h;
  
    /* +++ create right vertical border object +++ */
  
    /* load image */
    obj_vborder.img = VG3_image_load(wstruct, "vborder.bmp", 0);
    if (obj_vborder.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_vborder.img, NULL, &obj_vborder.rect.w, &obj_vborder.rect.h);
    obj_vborder.rect.x = winw - obj_vborder.rect.w;
    obj_vborder.rect.y = 0;
  
    /* +++ create ball object +++ */
  
    /* load image */
    obj_ball.img = VG3_image_load(wstruct, "ball.bmp", 0);
    if (obj_ball.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_ball.img, NULL, &obj_ball.rect.w, &obj_ball.rect.h);
    obj_ball.rect.x = (winw - obj_ball.rect.w) / 2;  /* x-position centered */
    obj_ball.rect.y = VG3_nw_get_random(0, winh - obj_ball.rect.h);  /* random y-position */
  
    /* set initial random moving-direction of the ball */
    xball = VG3_nw_get_random(1, 2);
    if (xball == 2) { xball = -1; }
    yball = VG3_nw_get_random(1, 2);
    if (yball == 2) { yball = -1; }
  
    /* +++ create player object +++ */
  
    /* load image */
    obj_player.img = VG3_image_load(wstruct, "player.bmp", 0);
    if (obj_player.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position centered at the left */
    VG3_image_getsize(wstruct, obj_player.img, NULL, &obj_player.rect.w, &obj_player.rect.h);
    obj_player.rect.x = 0;
    obj_player.rect.y = (winh - obj_player.rect.h) / 2;
  
    /* +++ load audio files +++ */
  
    /* audio: hit border and player */
    audio_hit = VG3_audio_load(wstruct, "hit.wav", 100, VGAG3_AUDIO_VOLUME_SOUND);
    if (audio_hit == 0) { fprintf(stderr, "loading hit.wav: %s\n", VG3_error()); return 0; }
  
    /* audio: game over */
    audio_gameover = VG3_audio_load(wstruct, "gameover.wav", 100, VGAG3_AUDIO_VOLUME_SOUND);
    if (audio_gameover == 0) { fprintf(stderr, "loading gameover.wav: %s\n", VG3_error()); return 0; }
  
    return 1;  /* ok */
  }
  

• Step 2.3
  
  The function move_objects().
  Each object is moved and checked against other relevant objects:
  - borders don't move, no check needed
  - the ball moves according to xball and yball and is checked against all objects
  - the player moves according to key-strokes and is checked against both horizontal borders
  

  /* move objects and check for interaction with other objects (touching) */
  static int
  move_objects(void)
  {
    /* +++ borders don't move +++ */
  
    /* +++ move ball +++ */
  
    /* move 3 pixels */
    obj_ball.rect.x += (xball * 3);
    obj_ball.rect.y += (yball * 3);
  
    /* check ball with upper horizontal border */
    if (obj_ball.rect.x + obj_ball.rect.w > obj_hborder_up.rect.x
    && obj_ball.rect.x < obj_hborder_up.rect.x + obj_hborder_up.rect.w) {
      if (obj_ball.rect.y < obj_hborder_up.rect.y + obj_hborder_up.rect.h) {
        obj_ball.rect.y = obj_hborder_up.rect.y + obj_hborder_up.rect.h + 1;
        yball = -yball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with lower horizontal border */
    if (obj_ball.rect.x + obj_ball.rect.w > obj_hborder_down.rect.x
    && obj_ball.rect.x < obj_hborder_down.rect.x + obj_hborder_down.rect.w) {
      if (obj_ball.rect.y + obj_ball.rect.h > obj_hborder_down.rect.y) {
        obj_ball.rect.y = obj_hborder_down.rect.y - obj_ball.rect.h;
        yball = -yball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with right vertical border */
    if (obj_ball.rect.y + obj_ball.rect.h > obj_vborder.rect.y
    && obj_ball.rect.y < obj_vborder.rect.y + obj_vborder.rect.h) {
      if (obj_ball.rect.x + obj_ball.rect.w > obj_vborder.rect.x) {
        obj_ball.rect.x = obj_vborder.rect.x - obj_ball.rect.w;
        xball = -xball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with player */
    if (obj_ball.rect.y + obj_ball.rect.h > obj_player.rect.y
    && obj_ball.rect.y < obj_player.rect.y + obj_player.rect.h) {
      if (obj_ball.rect.x < obj_player.rect.x + obj_player.rect.w) {
        obj_ball.rect.x = obj_player.rect.x + obj_player.rect.w;
        xball = -xball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball missing player: game over */
    if (obj_ball.rect.x + obj_ball.rect.w - 1 <= 0) { return 0; }
  
    /* +++ move player +++ */
  
    if (VG3_key_ispressed(wstruct, VGAG3_KEY_UCURS, VGAG3_IS_PRESSED)) {
      obj_player.rect.y -= 3;  /* move 3 pixels up */
      /* check player with upper horizontal border */
      if (obj_player.rect.y < obj_hborder_up.rect.y + obj_hborder_up.rect.h) {
        obj_player.rect.y = obj_hborder_up.rect.y + obj_hborder_up.rect.h;
      }
    }
  
    if (VG3_key_ispressed(wstruct, VGAG3_KEY_DCURS, VGAG3_IS_PRESSED)) {
      obj_player.rect.y += 3;  /* move 3 pixels down */
      /* check player with lower horizontal border */
      if (obj_player.rect.y + obj_player.rect.h > obj_hborder_down.rect.y) {
        obj_player.rect.y = obj_hborder_down.rect.y - obj_player.rect.h;
      }
    }
  
    return 1;
  }
  

• Step 2.4
  
  The function draw_objects().
  Each object is drawn onto the window at its new position.

  /* draw objects onto the window */
  static void
  draw_objects(void)
  {
    /* +++ draw borders +++ */
  
    /* upper horizontal border */
    VG3_image_copy(wstruct, NULL, obj_hborder_up.img,
                   obj_hborder_up.rect.x + obj_hborder_up.rect.w / 2,
                   obj_hborder_up.rect.y + obj_hborder_up.rect.h / 2, NULL, 0);
  
    /* lower horizontal border */
    VG3_image_copy(wstruct, NULL, obj_hborder_down.img,
                   obj_hborder_down.rect.x + obj_hborder_down.rect.w / 2,
                   obj_hborder_down.rect.y + obj_hborder_down.rect.h / 2, NULL, 0);
  
    /* right vertical border */
    VG3_image_copy(wstruct, NULL, obj_vborder.img,
                   obj_vborder.rect.x + obj_vborder.rect.w / 2,
                   obj_vborder.rect.y + obj_vborder.rect.h / 2, NULL, 0);
  
    /* +++ draw ball +++ */
  
    VG3_image_copy(wstruct, NULL, obj_ball.img,
                   obj_ball.rect.x + obj_ball.rect.w / 2,
                   obj_ball.rect.y + obj_ball.rect.h / 2, NULL, 0);
  
    /* +++ draw player +++ */
  
    VG3_image_copy(wstruct, NULL, obj_player.img,
                   obj_player.rect.x + obj_player.rect.w / 2,
                   obj_player.rect.y + obj_player.rect.h / 2, NULL, 0);
  }
  



• Putting together
  
  
  Finally we got the following file (main.c):

  #include <vgagames3.h>
  
  /* structure for objects: borders, ball, player */
  struct object {
    struct vg3_image *img; /* loaded image */
    struct vg3_rect rect;  /* position and size */
  };
  
  /* for simplicity declare variables globally, which are shared with functions */
  static struct vg3_window *wstruct;  /* window struct */
  static int winw, winh;  /* size of window */
  static struct object obj_hborder_up, obj_hborder_down, obj_vborder, obj_ball, obj_player;  /* objects */
  static int xball, yball;  /* moving direction of the ball */
  static int audio_hit, audio_gameover;  /* audio descriptors */
  
  /* static functions */
  static int create_objects(void);
  static int move_objects(void);
  static void draw_objects(void);
  
  
  int main(int argc, char **argv) {
    int coldef;
  
    /* open window */
    wstruct = VG3_window_new(argv[0], VGAG3_VGAVERSION_LOW, VGAG3_WINSCALE_BESTSCALE);
    if (wstruct == NULL) { fprintf(stderr, "%s\n", VG3_error()); exit(1); }
  
    /* get the size of the window */
    VG3_window_getsize(wstruct, &winw, &winh);
  
    /* create objects */
    if (!create_objects()) { goto endgame; }
  
    /* set initial color definition for window */
    coldef = VGAG3_COLORDEF_DEFAULT;
  
    /* print infos */
    printf("\n");
    printf("Keys:\n");
    printf("- cursor up, cursor down: move\n");
    printf("- spacebar: color change\n");
    printf("- ALT+Q: exit\n");
  
    /* +++ game-loop +++ */
  
    VG3_discard_input(wstruct);
    for (;;) {
      if (VG3_inputevent_update(wstruct) > 0) { break; }
  
      /* ALT+Q: exit */
      if (VG3_key_ispressed(wstruct, VGAG3_KEY_Q, VGAG3_IS_NEW_PRESSED)
        && VG3_key_ispressed(wstruct, VGAG3_KEY_LALT, VGAG3_IS_PRESSED)) { break; }
  
      /* change color to monochrome and vice versa? */
      if (VG3_key_ispressed(wstruct, VGAG3_KEY_SPACE, VGAG3_IS_NEW_PRESSED)) {
        if (coldef == VGAG3_COLORDEF_DEFAULT) {
          coldef = VGAG3_COLORDEF_GREY;
        } else {
          coldef = VGAG3_COLORDEF_DEFAULT;
        }
        VG3_window_attributes(wstruct, NULL, NULL, coldef, NULL);
      }
  
      /* clear window with halfdark blue background */
      VG3_draw_clear(wstruct, NULL, VG3_color_brightness(VGAG3_COLOR_BLUE, 50));
  
      /* move objects and check for interaction with other objects (touching) */
      if (!move_objects()) { break; }
  
      /* draw objects onto the window */
      draw_objects();
  
      /* draw out window-contents */
      VG3_window_update(wstruct, 0, 0);
  
      /* sleep until 30 msec are gone for this game-loop */
      VG3_wait_time(30);
    }
    VG3_discard_input(wstruct);
  
    /* +++ game over +++ */
  
    /* play gameover.wav and wait for finishing */
    VG3_audio_play(wstruct, audio_gameover, 0, 0);
    while (VG3_audio_isplaying(wstruct, audio_gameover)) { VG3_wait_time(100); }
  
    /* clean up */
    VG3_image_unload(wstruct, NULL);
    VG3_audio_unload(wstruct, VG3_audio_group(VGAG3_AUDIO_VOLUME_ALL));
  
  endgame:
    /* close window and exit */
    VG3_window_free(wstruct);
    exit(0);
  }
  
  
  /* create objects and load audio files */
  static int
  create_objects(void)
  {
    /* +++ create upper horizontal border object +++ */
  
    /* load image */
    obj_hborder_up.img = VG3_image_load(wstruct, "hborder.bmp", 0);
    if (obj_hborder_up.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_hborder_up.img, NULL, &obj_hborder_up.rect.w, &obj_hborder_up.rect.h);
    obj_hborder_up.rect.x = obj_hborder_up.rect.y = 0;
  
    /* +++ create lower horizontal border object +++ */
  
    /* load image */
    obj_hborder_down.img = VG3_image_load(wstruct, "hborder.bmp", 0);
    if (obj_hborder_down.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_hborder_down.img, NULL, &obj_hborder_down.rect.w, &obj_hborder_down.rect.h);
    obj_hborder_down.rect.x = 0;
    obj_hborder_down.rect.y = winh - obj_hborder_down.rect.h;
  
    /* +++ create right vertical border object +++ */
  
    /* load image */
    obj_vborder.img = VG3_image_load(wstruct, "vborder.bmp", 0);
    if (obj_vborder.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_vborder.img, NULL, &obj_vborder.rect.w, &obj_vborder.rect.h);
    obj_vborder.rect.x = winw - obj_vborder.rect.w;
    obj_vborder.rect.y = 0;
  
    /* +++ create ball object +++ */
  
    /* load image */
    obj_ball.img = VG3_image_load(wstruct, "ball.bmp", 0);
    if (obj_ball.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position */
    VG3_image_getsize(wstruct, obj_ball.img, NULL, &obj_ball.rect.w, &obj_ball.rect.h);
    obj_ball.rect.x = (winw - obj_ball.rect.w) / 2;  /* x-position centered */
    obj_ball.rect.y = VG3_nw_get_random(0, winh - obj_ball.rect.h);  /* random y-position */
  
    /* set initial random moving-direction of the ball */
    xball = VG3_nw_get_random(1, 2);
    if (xball == 2) { xball = -1; }
    yball = VG3_nw_get_random(1, 2);
    if (yball == 2) { yball = -1; }
  
    /* +++ create player object +++ */
  
    /* load image */
    obj_player.img = VG3_image_load(wstruct, "player.bmp", 0);
    if (obj_player.img == NULL) { fprintf(stderr, "%s\n", VG3_error()); return 0; }
  
    /* get width and height of image and set position centered at the left */
    VG3_image_getsize(wstruct, obj_player.img, NULL, &obj_player.rect.w, &obj_player.rect.h);
    obj_player.rect.x = 0;
    obj_player.rect.y = (winh - obj_player.rect.h) / 2;
  
    /* +++ load audio files +++ */
  
    /* audio: hit border and player */
    audio_hit = VG3_audio_load(wstruct, "hit.wav", 100, VGAG3_AUDIO_VOLUME_SOUND);
    if (audio_hit == 0) { fprintf(stderr, "loading hit.wav: %s\n", VG3_error()); return 0; }
  
    /* audio: game over */
    audio_gameover = VG3_audio_load(wstruct, "gameover.wav", 100, VGAG3_AUDIO_VOLUME_SOUND);
    if (audio_gameover == 0) { fprintf(stderr, "loading gameover.wav: %s\n", VG3_error()); return 0; }
  
    return 1;  /* ok */
  }
  
  
  /* move objects and check for interaction with other objects (touching) */
  static int
  move_objects(void)
  {
    /* +++ borders don't move +++ */
  
    /* +++ move ball +++ */
  
    /* move 3 pixels */
    obj_ball.rect.x += (xball * 3);
    obj_ball.rect.y += (yball * 3);
  
    /* check ball with upper horizontal border */
    if (obj_ball.rect.x + obj_ball.rect.w > obj_hborder_up.rect.x
    && obj_ball.rect.x < obj_hborder_up.rect.x + obj_hborder_up.rect.w) {
      if (obj_ball.rect.y < obj_hborder_up.rect.y + obj_hborder_up.rect.h) {
        obj_ball.rect.y = obj_hborder_up.rect.y + obj_hborder_up.rect.h + 1;
        yball = -yball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with lower horizontal border */
    if (obj_ball.rect.x + obj_ball.rect.w > obj_hborder_down.rect.x
    && obj_ball.rect.x < obj_hborder_down.rect.x + obj_hborder_down.rect.w) {
      if (obj_ball.rect.y + obj_ball.rect.h > obj_hborder_down.rect.y) {
        obj_ball.rect.y = obj_hborder_down.rect.y - obj_ball.rect.h;
        yball = -yball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with right vertical border */
    if (obj_ball.rect.y + obj_ball.rect.h > obj_vborder.rect.y
    && obj_ball.rect.y < obj_vborder.rect.y + obj_vborder.rect.h) {
      if (obj_ball.rect.x + obj_ball.rect.w > obj_vborder.rect.x) {
        obj_ball.rect.x = obj_vborder.rect.x - obj_ball.rect.w;
        xball = -xball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball with player */
    if (obj_ball.rect.y + obj_ball.rect.h > obj_player.rect.y
    && obj_ball.rect.y < obj_player.rect.y + obj_player.rect.h) {
      if (obj_ball.rect.x < obj_player.rect.x + obj_player.rect.w) {
        obj_ball.rect.x = obj_player.rect.x + obj_player.rect.w;
        xball = -xball;
        VG3_audio_play(wstruct, audio_hit, 0, 0);  /* play hit.wav */
      }
    }
  
    /* check ball missing player: game over */
    if (obj_ball.rect.x + obj_ball.rect.w - 1 <= 0) { return 0; }
  
    /* +++ move player +++ */
  
    if (VG3_key_ispressed(wstruct, VGAG3_KEY_UCURS, VGAG3_IS_PRESSED)) {
      obj_player.rect.y -= 3;  /* move 3 pixels up */
      /* check player with upper horizontal border */
      if (obj_player.rect.y < obj_hborder_up.rect.y + obj_hborder_up.rect.h) {
        obj_player.rect.y = obj_hborder_up.rect.y + obj_hborder_up.rect.h;
      }
    }
  
    if (VG3_key_ispressed(wstruct, VGAG3_KEY_DCURS, VGAG3_IS_PRESSED)) {
      obj_player.rect.y += 3;  /* move 3 pixels down */
      /* check player with lower horizontal border */
      if (obj_player.rect.y + obj_player.rect.h > obj_hborder_down.rect.y) {
        obj_player.rect.y = obj_hborder_down.rect.y - obj_player.rect.h;
      }
    }
  
    return 1;
  }
  
  
  /* draw objects onto the window */
  static void
  draw_objects(void)
  {
    /* +++ draw borders +++ */
  
    /* upper horizontal border */
    VG3_image_copy(wstruct, NULL, obj_hborder_up.img,
                   obj_hborder_up.rect.x + obj_hborder_up.rect.w / 2,
                   obj_hborder_up.rect.y + obj_hborder_up.rect.h / 2, NULL, 0);
  
    /* lower horizontal border */
    VG3_image_copy(wstruct, NULL, obj_hborder_down.img,
                   obj_hborder_down.rect.x + obj_hborder_down.rect.w / 2,
                   obj_hborder_down.rect.y + obj_hborder_down.rect.h / 2, NULL, 0);
  
    /* right vertical border */
    VG3_image_copy(wstruct, NULL, obj_vborder.img,
                   obj_vborder.rect.x + obj_vborder.rect.w / 2,
                   obj_vborder.rect.y + obj_vborder.rect.h / 2, NULL, 0);
  
    /* +++ draw ball +++ */
  
    VG3_image_copy(wstruct, NULL, obj_ball.img,
                   obj_ball.rect.x + obj_ball.rect.w / 2,
                   obj_ball.rect.y + obj_ball.rect.h / 2, NULL, 0);
  
    /* +++ draw player +++ */
  
    VG3_image_copy(wstruct, NULL, obj_player.img,
                   obj_player.rect.x + obj_player.rect.w / 2,
                   obj_player.rect.y + obj_player.rect.h / 2, NULL, 0);
  }
  



• Running
  
  
  

  Running the game