no-reply@allegro.cc (Jefferson Almeida) — Thu, 17 Mar 2011 08:28:31 +0000

I based the tutorial which is on the wiki!
Files for download: http://www.megaupload.com/?d=YRXGH41L

This compiles fine without errors but when "Build and Run" show the message of the code: "Failed to load sword image!"

#SelectExpand
   1/*
   2======================================
   3
   4Tela inicial com alguns testes do meu aprendizado.
   5Autor: Jefferson [allos_nerelin]
   6
   7======================================
   8*/
   9
  10#include 
  11#include 
  12#include 
  13#include 
  14
  15const float FPS = 60;
  16const int SCREEN_W = 640;
  17const int SCREEN_H = 480;
  18const int BOUNCER_SIZE = 32;
  19
  20
  21
  22int main(int argc, char **argv)
  23{
  24   ALLEGRO_DISPLAY *display = NULL;
  25   ALLEGRO_EVENT_QUEUE *event_queue = NULL;
  26   ALLEGRO_TIMER *timer = NULL;
  27   ALLEGRO_BITMAP *sword;
  28   ALLEGRO_MOUSE_CURSOR *cursor;
  29   float bouncer_x = SCREEN_W / 2.0 - BOUNCER_SIZE / 2.0;
  30   float bouncer_y = SCREEN_H / 2.0 - BOUNCER_SIZE / 2.0;
  31   bool redraw = true;
  32
  33   if(!al_init()) {
  34      fprintf(stderr, "failed to initialize allegro!\n");
  35      return -1;
  36   }
  37
  38   if(!al_install_mouse()) {
  39      fprintf(stderr, "failed to initialize the mouse!\n");
  40      return -1;
  41   }
  42
  43   if(!al_init_primitives_addon()) {
  44      fprintf(stderr, "Failed to initialize the primitives addon!\n");
  45      return -1;
  46   }
  47
  48   if (!al_init_image_addon()) {
  49       fprintf(stderr, "Failed to initialize the image addon!\n");
  50       return -1;
  51   }
  52
  53
  54   timer = al_create_timer(1.0 / FPS);
  55   if(!timer) {
  56      fprintf(stderr, "failed to create timer!\n");
  57      return -1;
  58   }
  59
  60   display = al_create_display(SCREEN_W, SCREEN_H);
  61   if(!display) {
  62      fprintf(stderr, "failed to create display!\n");
  63      al_destroy_timer(timer);
  64      return -1;
  65   }
  66
  67   sword = al_load_bitmap("sword.bmp");
  68   if(!sword) {
  69      fprintf(stderr, "Failed to load sword image!\n");
  70      return -1;
  71   }
  72
  73   cursor = al_create_mouse_cursor(sword, 16, 16);
  74   if(!cursor) {
  75      fprintf(stderr, "Failed to load the cursor!\n");
  76      return -1;
  77   }
  78
  79   al_clear_to_color(al_map_rgb(255, 0, 255));
  80
  81   al_set_target_bitmap(al_get_backbuffer(display));
  82
  83   event_queue = al_create_event_queue();
  84   if(!event_queue) {
  85      fprintf(stderr, "failed to create event_queue!\n");
  86      al_destroy_display(display);
  87      al_destroy_timer(timer);
  88      return -1;
  89   }
  90
  91   al_register_event_source(event_queue, al_get_display_event_source(display));
  92
  93   al_register_event_source(event_queue, al_get_timer_event_source(timer));
  94
  95   al_register_event_source(event_queue, al_get_mouse_event_source());
  96
  97   al_clear_to_color(al_map_rgb(0,0,0));
  98
  99   al_flip_display();
 100
 101   al_start_timer(timer);
 102
 103   while(1)
 104   {
 105      ALLEGRO_EVENT ev;
 106      al_wait_for_event(event_queue, &ev);
 107
 108      if(ev.type == ALLEGRO_EVENT_TIMER) {
 109         redraw = true;
 110      }
 111      else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) {
 112         break;
 113      }
 114      else if(ev.type == ALLEGRO_EVENT_MOUSE_AXES ||
 115              ev.type == ALLEGRO_EVENT_MOUSE_ENTER_DISPLAY) {
 116
 117         bouncer_x = ev.mouse.x;
 118         bouncer_y = ev.mouse.y;
 119      }
 120      else if(ev.type == ALLEGRO_EVENT_MOUSE_BUTTON_UP) {
 121          break;
 122      }
 123
 124      if(redraw && al_is_event_queue_empty(event_queue)) {
 125         redraw = false;
 126
 127         al_clear_to_color(al_map_rgb(0,0,0));
 128
 129         al_flip_display();
 130      }
 131   }
 132
 133   al_destroy_timer(timer);
 134   al_destroy_display(display);
 135   al_destroy_event_queue(event_queue);
 136
 137   return 0;
 138}

no-reply@allegro.cc (Matthew Leverton) — Thu, 17 Mar 2011 09:02:24 +0000

Site notes:

use tags when posting source code
use the built-in file attachment functionality instead of third party sites

Regarding the problem at hand:

Does the image exist on your file system?
If so, then the working directory isn't set properly.

Solutions:

Use an absolute path for the file name. (temporary solution)
Use al_get_standard_path() and related functions to switch to the appropriate location where the file is located before loading it.

no-reply@allegro.cc (Neil Walker) — Thu, 17 Mar 2011 18:37:56 +0000

That's the second image load error due to relative/working paths I've seen this week.

Perhaps on the next document update, somebody could mention this in the load methods?

I can see a helper method something like:
al_load_bitmap_relative("resources/sword.bmp", ALLEGRO_EXENAME_PATH)

being quite useful in the wiki.

no-reply@allegro.cc (Matthew Leverton) — Thu, 17 Mar 2011 23:36:39 +0000

EXENAME is not the proper constant to use. It would break on OS X bundles. RESOURCES is the place to look for bundled data.

You would need a function for each loader and saver... it's better to understand what's going on. Note that you really probably only need to do this:

ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);

// ... append the media component to path

al_change_directory(al_path_cstr(path));

al_load_bitmap("foo.png");

I assume that works if you are using the standard I/O functions.

My code work but no load the sword.bmp image