bitmap loading problems

Fworg64

Ive had trouble with this function since i first started using allegro 5 (a month ago ).
It seems that al_load_bitmap refuses to load a bitmap for me, i had gotten it to work for a while but then after i changed a couple lines somewhere it stopped,
heres my code

#SelectExpand
   1
   2#include <stdio.h>
   3#include <allegro5/allegro.h>
   4#include <allegro5/allegro_image.h>
   5#include <time.h>
   6#include <cstdlib>
   7
   8const int SCREEN_W = 640;
   9const int SCREEN_H = 480;
  10const int FPS = 60;
  11const int OBJECTD = 16;
  12const float UPR=1;
  13const float UPL=2;
  14const float DNR=3;
  15const float DNL=0;
  16int num_of_enemy;
  17
  18class Game
  19{
  20    public:
  21        ALLEGRO_DISPLAY *display;
  22        ALLEGRO_EVENT_QUEUE *event_queue;
  23        ALLEGRO_TIMER *timer;
  24        bool Init();
  25};
  26
  27bool Game::Init()
  28{
  29    if (!al_init()) {fprintf(stderr,"failed to initialize allegro!\n");return false;}
  30    if (!al_install_keyboard()) {fprintf(stderr,"failed to install keyboard drivers!\n");return false;}
  31    if (!al_init_image_addon()) {fprintf(stderr,"failed to initialize image addon\n");return false;}
  32
  33    display = al_create_display(SCREEN_W,SCREEN_H);
  34    event_queue = al_create_event_queue();
  35    timer = al_create_timer(1.0/FPS);
  36
  37    if (!display) {fprintf(stderr,"failed to create display!\n"); return false;}
  38    if (!event_queue) {fprintf(stderr,"failed to create event queue!\n"); al_destroy_display(display); return false;}
  39    if (!timer) {fprintf(stderr,"failed to create timer!\n"); al_destroy_display(display); al_destroy_event_queue(event_queue);return false;}
  40
  41    al_register_event_source(event_queue, al_get_display_event_source(display));
  42    al_register_event_source(event_queue, al_get_timer_event_source(timer));
  43    al_register_event_source(event_queue, al_get_keyboard_event_source());
  44
  45    return true;
  46}
  47
  48class Object
  49{
  50    int x;
  51    int y;
  52    int d;
  53    ALLEGRO_BITMAP *bitmap;
  54    public:
  55        Object(bool player);
  56        Object();
  57        void Move(ALLEGRO_KEYBOARD_STATE *state);
  58        void Move();
  59        void Draw();
  60        bool Collide(Object victim);
  61};
  62
  63Object::Object(bool player)
  64{
  65    if (player)
  66    {
  67        x = (SCREEN_W - OBJECTD)/2;
  68        y = (SCREEN_H - OBJECTD)/2;
  69        bitmap = al_load_bitmap("playerball.bmp");
  70        if (bitmap == NULL) printf("erroer loding bitmap\n"); //displays this, meaning bitmap failed to load
  71        al_convert_mask_to_alpha(bitmap,al_map_rgb(255,255,255)); // actually crashes on this line, most likely because the bitmap is null
  72    }
  73}
  74
  75Object::Object()
  76{
  77        d = rand() % 4;
  78        x = rand() %SCREEN_H;
  79        y = rand() %SCREEN_W;
  80        bitmap = al_load_bitmap("cpuball.bmp");
  81        al_convert_mask_to_alpha(bitmap,al_map_rgb(255,255,255));
  82}
  83
  84void Object::Move(ALLEGRO_KEYBOARD_STATE *state)
  85{
  86    printf("1 ");
  87    if ((al_key_down(state,ALLEGRO_KEY_UP) || al_key_down(state,ALLEGRO_KEY_W)) && y>0) y--;
  88    printf("2 ");
  89    if ((al_key_down(state,ALLEGRO_KEY_DOWN) || al_key_down(state,ALLEGRO_KEY_S)) && (y+OBJECTD)<SCREEN_H) y++;
  90    printf("3 ");
  91    if ((al_key_down(state,ALLEGRO_KEY_LEFT) || al_key_down(state,ALLEGRO_KEY_A)) && x>0) x--;
  92    printf("4 ");
  93    if ((al_key_down(state,ALLEGRO_KEY_RIGHT) || al_key_down(state,ALLEGRO_KEY_D)) && (x+OBJECTD)<SCREEN_W) x++;
  94    printf("5 \n");
  95}
  96
  97void Object::Move()
  98{
  99    if (x==0 && d==UPL) {d=UPR;}
 100    if (x==0 && d==DNL) {d=DNR;}
 101    if (x==(SCREEN_W-OBJECTD) && d==DNR) {d=DNL;}
 102    if (x==(SCREEN_W-OBJECTD) && d==UPR) {d=UPL;}
 103    if (y==0 && d==UPL) {d=DNL;}
 104    if (y==0 && d==UPR) {d=DNR;}
 105    if (y==(SCREEN_H-OBJECTD) && d==DNR) {d=UPR;}
 106    if (y==(SCREEN_H-OBJECTD) && d==DNL) {d=UPL;}
 107    if (d == UPR) {y--;x++;}
 108    if (d == UPL) {y--;x--;}
 109    if (d == DNR) {y++;x++;}
 110    if (d == DNL) {y++;x--;}
 111}
 112
 113void Object::Draw()
 114{
 115    printf("object.draw\n");
 116    al_draw_bitmap(bitmap,x,y,0);
 117}
 118
 119bool Object::Collide(Object victim)
 120{
 121
 122}
 123
 124int main()
 125{
 126    srand(time(NULL));
 127
 128    Game Sally;
 129    if (!Sally.Init()) {printf("Your Screwed\n"); return -1;}
 130
 131    Object Billy(true);
 132    num_of_enemy = 5;
 133    Object *Enemy;
 134    Enemy = new Object[num_of_enemy];
 135    bool redraw = true;
 136
 137    al_set_target_bitmap(al_get_backbuffer(Sally.display));
 138    al_set_window_title(Sally.display,"TITLE");
 139    al_clear_to_color(al_map_rgb(250,100,19));
 140    al_flip_display();
 141
 142    al_start_timer(Sally.timer);
 143
 144    printf("starting loop\n");
 145
 146    ALLEGRO_KEYBOARD_STATE *ret_state;
 147    ret_state = new ALLEGRO_KEYBOARD_STATE;
 148
 149    while (true)
 150    {
 151        ALLEGRO_EVENT ev;
 152        al_wait_for_event(Sally.event_queue,&ev);
 153
 154        if (ev.type == ALLEGRO_EVENT_TIMER)
 155        {
 156            printf("timer\n");
 157            Billy.Move(ret_state);
 158            for (int a=0;a<num_of_enemy;a++)
 159            {
 160                Enemy[a].Move();
 161            }
 162            redraw = true;
 163        }
 164
 165        else if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
 166        {
 167            printf("keypressfghjiulkyjrtyuiiuytrtyuiuiy\n");
 168            al_get_keyboard_state(ret_state);
 169        }
 170
 171        else if (ev.type == ALLEGRO_EVENT_KEY_UP)
 172        {
 173            printf("keyrelaesesfghjiulkyjrtyuiiuytrtyuiuiy\n");
 174            al_get_keyboard_state(ret_state);
 175        }
 176
 177        else if (ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
 178        {
 179            printf("close\n");
 180            al_destroy_timer(Sally.timer);
 181            al_destroy_display(Sally.display);
 182            al_destroy_event_queue(Sally.event_queue);
 183            return 0;
 184        }
 185
 186        if (redraw && al_is_event_queue_empty(Sally.event_queue))
 187        {
 188            printf("redraw\n");
 189            al_clear_to_color(al_map_rgb(50,50,50));
 190            Billy.Draw();
 191            for (int a=0;a<num_of_enemy;a++)
 192            {
 193                Enemy[a].Draw();
 194            }
 195            al_flip_display();
 196            redraw = false;
 197        }
 198    }
 199
 200    return 0;
 201}

lines 69-71 are where it crashes

as a side note i double checked the spelling and the image file is in fact next to the .exe, Ive also attached the two image files.

Matthew Leverton

Throw a fprintf in Game::init to make sure Allegro is being initialized before any bitmaps are loaded.

It could also be a path issue. al_filename_exists() will return true if the file is where it should be.

someone972

If Allegro isn't being initialized first I'd try changing Object Billy(true); to Object* Billy = new Object(true); and see if that works.

Edgar Reynaldo

Make sure your game is being run from the same directory that it is in, otherwise relative paths will not work correctly.

Fworg64

After following your guys's advice i found it must be a path issue, allegro is initialized judging by the al_is_system_installed() function i added right before the al_load_bitmap. It must then be a path error which i cant grasp why, the file is named how it should and is right next to the .exe. the only modifications ive made to the program is now Object::Object(bool player) is as follows.

Object::Object(bool player)
{
    if (player)
    {
        x = (SCREEN_W - OBJECTD)/2;
        y = (SCREEN_H - OBJECTD)/2;
        if (al_is_system_installed()) printf("allegro is installed\n");// true
        if (!al_filename_exists("playerball.bmp")) printf("it doesnt exist\n");// the file does not exist
        bitmap = al_load_bitmap("playerball.bmp");
        if (bitmap == NULL) printf("erroer loding bitmap\n");// the pointer is null
        al_convert_mask_to_alpha(bitmap,al_map_rgb(255,255,255));
    }
}

not much changed (nothing functionally at least)

EDIT::Found the problem, was in fact a Path problem but not my fault,
my IDE code::blocks which i was running my program from, uses the project folder to look for resources and files, not the debug folder that holds the .exe where most would assume. The program runs when launched normally but will only function when launched from the IDE if the resources are in the main project folder! 8-)

Edgar Reynaldo

You can fix this by setting the execution working directory of each build type of your project. Go to Project->Properties->Build Targets and set that to the directory where your program is built. You can see this by looking slightly up to the Output Filename textbox :

{"name":"604019","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/5\/c5d1dbcc351316d031ee7874dec1ebaf.png","w":702,"h":483,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/5\/c5d1dbcc351316d031ee7874dec1ebaf"}

Thread #607141. Printed from Allegro.cc