Can't load bitmap from a zipfile (PhysFS addon help)

no-reply@allegro.cc (Restful Cargo) — Tue, 03 Nov 2015 17:45:07 +0000

Hello Allegro fans. Allegro newbie and first time poster (please be gentle). I am having trouble getting al_load_bitmap to work with the PhysFS addon. I am using allegro_monolith-debug-5.1.dll from the allegro-msvc2013-x86-5.1.12.zip with PhysFS 2.0.3 and VS2013. I've searched and read the manual and forums threads but without success.

The program is supposed to load a bitmap from a zip file and display it. The code successfully inits everything. It loads the zip file then calls al_set_physfs_file_interface(). Then it proceeds to check if file dodo.bmp exists (which it does). The program then explodes when calling al_load_bitmap(). Visual Studio debugger complains that an access violation exception happened.

I have no idea what I am doing wrong. If anyone could help I'd appreciate it.

#SelectExpand
  1#include 
  2#include 
  3#include 
  4#include 
  5#include 
  6
  7int main(int argc, char *argv[])
  8{
  9  ALLEGRO_DISPLAY *display = NULL;
 10  ALLEGRO_BITMAP *image;
 11  
 12  al_init();
 13  al_init_image_addon();
 14
 15  display = al_create_display(320, 200);
 16  al_clear_to_color(al_map_rgb(0, 0, 0));
 17  
 18  if (PHYSFS_init(argv[0]) != 0)
 19    if (PHYSFS_mount("test.zip","/",0))
 20      al_set_physfs_file_interface();
 21    else
 22      exit(1);
 23  else
 24    exit(1);
 25
 26  if (PHYSFS_exists("dodo.bmp"))  
 27  {
 28    image = al_load_bitmap("dodo.bmp");  // <--- CRASHES HERE
 29
 30  } else {
 31    printf("bmp not found");
 32    exit(1);
 33  }  
 34
 35  al_draw_bitmap(image, 0, 0, 0);
 36  al_flip_display();
 37  al_rest(5);
 38
 39  return 0;
 40}

no-reply@allegro.cc (RPG Hacker) — Tue, 03 Nov 2015 18:55:38 +0000

This is quite a step in the dark... but does "/dodo.bmp" work?
One guess of mine is that you need to add the mount point to the file name when trying to load a file from it.

no-reply@allegro.cc (Arthur Kalliokoski) — Tue, 03 Nov 2015 20:04:18 +0000

I just tried your program on Linux and it worked. Perhaps dodo.bmp is some weird 16 color bitmap that Allegro can't handle? Try loading it without the zipfile stuff.

no-reply@allegro.cc (Restful Cargo) — Tue, 03 Nov 2015 20:17:10 +0000

EDIT: Good to hear it works for someone! I tried it with different files. The 02.bmp from the data folder in allegro, a png file, and a couple other bmp's. They're small images. Nothing huge or special about them. I can load files fine directly from the hard drive but can't get the PHYSFS addon to work properly.

@RPG Hacker: Sorry just tried it. Same results. Thanks anyway. Using the older PHYSFS_addToSearchPath() instead of PHYSFS_mount doesn't make a difference either. I get the same problem with the ex_physfs demo. Maybe it's a problem with my Visual Studio. I don't know.

[SOLUTION]
As suggested in another thread I took a look at the "linker->input->additional dependencies" in my project's properties window. For the program to work physfs.lib has to be declared after allegro_monolith-debug.lib (or whatever you use). At least that fixed it for my case. Thanks RPG Hacker and Arthur Kalliokoski for your attention.

no-reply@allegro.cc (SiegeLord) — Wed, 04 Nov 2015 11:12:11 +0000

I just tried this with my MSVC2013 and it seemed to work fine... I used x86 allegro_monolith-debug.lib too. The change you made doesn't seem to make sense to me, since that dependency should have been already linked in that library...