Having a problem with ALLEGRO_BITMAP and a vector.

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 16:00:28 +0000

For some reason my head is not on strait and I cannot work this out.

The code below loads the bitmap I do know that and then when adding it to the vector it just crashes. I'm trying to write this so that I can use it over and over again in my project but without even getting the rest added I need to get this fixed.

Any help would be very appreciated.

#SelectExpand
  1#include 
  2#include 
  3
  4#include 
  5#include 
  6
  7std::vector<ALLEGRO_BITMAP*> texture;
  8
  9bool LoadTexture( const char* filename, int id )
 10{
 11  ALLEGRO_BITMAP* temp_bmp = al_load_bitmap( filename );
 12  if ( !temp_bmp )
 13    return false;
 14
 15  if ( id > (signed)texture.size() )
 16    texture.resize( id );
 17
 18  texture[id] = temp_bmp; // Breaks with this line.
 19
 20  printf( "Loaded Texture: %s\n", filename );
 21
 22  return true;
 23}
 24
 25void DeleteAllTextures()
 26{
 27  for ( unsigned int i = 0; i < texture.size(); i++ )
 28  {
 29    if ( texture[i] )
 30    {
 31      al_destroy_bitmap( texture[i] );
 32      printf( "Deleted Texture: #%i\n", i );
 33    }
 34  }
 35}
 36
 37int main()
 38{
 39    al_init();
 40
 41    al_init_image_addon();
 42
 43    if ( !LoadTexture( "media/player.bmp", 0 ) )
 44        printf( "Failed to load Texture!\n" );
 45
 46    DeleteAllTextures();
 47
 48    al_shutdown_image_addon();
 49
 50    return 0;
 51}

no-reply@allegro.cc (Edgar Reynaldo) — Fri, 06 May 2011 16:03:39 +0000

Think about the size of the vector for a second. If you use 'resize(10)' then what is the greatest index you can access of the vector? It's 9, or in your case 'size() - 1'. You need to resize the vector to 'id + 1' so you can access vector[id].

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 16:07:07 +0000

I tried texture.resize( id+1 ); and even tried texture.resize( id+100 );

I still get it crashing

This is why it is confusing me.

Append: Fixed it. It was.

#SelectExpand
 1if ( id > (signed)texture.size() )

And should have been.

#SelectExpand
 1if ( id >= (signed)texture.size() )

no-reply@allegro.cc (Edgar Reynaldo) — Fri, 06 May 2011 16:14:04 +0000

Try this :

   if ( id >= (signed)texture.size() ) {
      texture.resize( id + 1);
   }

Note the >= sign instead of >.

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 16:15:16 +0000

, yea, Thanks. I just realized that though

no-reply@allegro.cc (Edgar Reynaldo) — Fri, 06 May 2011 16:23:14 +0000

Maybe you would like a std::map better?

Then you could lookup textures by their name. Just an idea, it may not suit you.

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 16:27:12 +0000

This is my kind of idea.

#SelectExpand
  1bool SetDisplayMode( int width, int height );
  2bool SetWindowTitle( const char* title );
  3void SyncRate( int rate );
  4bool DoLoop(); // Checks for new events and tells us if we are to redraw.
  5
  6bool LoadTexture( const char* filename, int id );
  7void BlitTexture( int id, int x, int y, int alpha );
  8void SetColorKey( int id, int r, int g, int b );
  9void DeleteTexture( int id );
 10
 11void Sync(); // Updates the display.
 12
 13void CreateSprite( int id );
 14void SetSpriteTexture( int id, int imgid );
 15void SetSpriteCoord( int id, int x, int y );
 16void SetSpriteAlpha( int id, int alpha );
 17void RotateSprite( int id, float angle );
 18void BlitSprite( int id );
 19void MoveSprite( int id, int amount );
 20bool SpriteCollision(  int sprite1, int sprite2 );
 21void DeleteSprite( int id );
 22
 23bool LoadSound( const char* filename, int id );
 24void PlaySound( int id );
 25void LoopSound( int id );
 26void StopSound( int id );
 27void SetSoundSpeed( int id, float speed );
 28void SetSoundGain( int id, float gain );
 29void SetSoundPan( int id, float pan );
 30void DeleteSound( int id );
 31
 32bool LoadFont( const char* filename, int size, int id );
 33void BlitText( const char* text, int x, int y, int r, int g, int b );
 34void BlitCentered( const char* text, int x, int y, int r, int g, int b );
 35void DeleteFont( int id );

This is to make it quicker for making games. There will be a lot more functions but I'm working on the main ones at the moment.

I could use std::map but either way works

no-reply@allegro.cc (Edgar Reynaldo) — Fri, 06 May 2011 16:30:09 +0000

All those ids make me dizzy.

How do you keep track of which id you want to use? I suppose you store it in a class?

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 16:35:14 +0000

To keep track of it would be as you said different classes or you can name the numbers using...

#define PLAYER_TEXTURE = 0
#define ENEMY_TEXTURE = 1
...

This is how DarkGDK works and I like the way it's so basic. Obviously the basic stuff I need to code the more complex stuff first but then when I make games I can just use my own library instead

no-reply@allegro.cc (Audric) — Fri, 06 May 2011 17:38:47 +0000

Something suspicious about the sound API: does id refer to a sound resource, or one instance of a sound being played ? ie: If two long "character babble" sounds are playing at the same time, how does StopSound know which one it should cut ?
Same with SetSoundPan if it's for stereo and SetSoundGain for volume.

no-reply@allegro.cc (Desmond Taylor) — Fri, 06 May 2011 18:53:14 +0000

It will be stored in a struct with the relevant ID. Then to stop it the instance id is taken from the struct.

I shall be adding more commands than just those. That's just a mockup idea not the actual functions.