Allegro 5 file system

Ariesnl

Since the native file dialog doesn't look so nice and also crashes the Windows version of my game. I wanted to make a save/ load screen with a list of slots.
I thought the allegro 5 file system was a nice feature to use for that.
However I saw a "warning" not to use the file's path but the ALLEGRO_FS_ENTRY itself to open the file ? How would I do that ?

Correction.. the Dialog wasn't the problem.. it seems you cannot load a file in windows that was saved in linux for some reason... strange.. looking up the version number just went fine??

RPG Hacker

Ariesnl said:

However I saw a "warning" not to use the file's path but the ALLEGRO_FS_ENTRY itself to open the file ? How would I do that

Is this what you're looking for?

Quote:

it seems you cannot load a file in windows that was saved in linux for some reason... strange.. looking up the version number just went fine??

How exactly are you saving the data? Are you just putting a pointer of a struct into a file stream? In that case, yeah, the save file won't be platform-independent. Every compiler has different rules for packing of structs and every architecture has its own endianness. Those and probably some more things influence how the data written to the file will be interpreted when read back. If you want truley platform-independent save files, you'll have to work at a byte level. Only write singular bytes to the file stream and do the conversion (multiple bytes <-> actual data type) yourself. Note that this is a lot slower and you're probably better just having platform-dependent save files, for the sake of the game. In my opinion, sharing save files between different platforms isn't really that important, anyways.

Ariesnl

Partly it is.. however, trying to be "modern" all my load and save routines use C++ filestream... I'm afraid that won't map to a filepointer system ?
It serializes the current game engine contents and after that the complete universe to an opened filestream.

By the way: g_pUniverse->StoreSector stores the Game engine contents into the current sector.( like the number of ships of a certain kind etc.)

#SelectExpand
  1void SaveGame()
  2{
  3    ALLEGRO_FILECHOOSER * dlg = NULL;
  4    ALLEGRO_PATH        * pSavePath  = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
  5
  6    al_append_path_component(pSavePath, "Save");
  7
  8    dlg = al_create_native_file_dialog(        al_path_cstr(pSavePath,ALLEGRO_NATIVE_PATH_SEP),
  9
 10                                        "Save Game...",
 11
 12                                        "*.uni",
 13
 14                                        ALLEGRO_FILECHOOSER_SAVE);
 15
 16    if (al_show_native_file_dialog(g_pDisplay,dlg))
 17
 18    {
 19
 20        ofstream SaveFile(al_get_native_file_dialog_path(dlg, 0),ios::out | ios::binary);
 21
 22        if (SaveFile)
 23
 24        {
 25
 26            g_pUniverse->StoreSector(g_pEnterprise->m_nSectorPositionX,g_pEnterprise->m_nSectorPositionY,g_pEngine);
 27
 28            g_pEngine->Save(SaveFile);
 29
 30            g_pUniverse->Save(SaveFile);
 31
 32            SaveFile.close();
 33
 34        }
 35
 36        else
 37
 38        {
 39
 40            // handle error
 41
 42        }
 43
 44
 45
 46    }
 47
 48
 49
 50    al_destroy_native_file_dialog(dlg);
 51
 52}

RPG Hacker

Ariesnl said:

I'm afraid that won't map to a filepointer system ?

Well, not mapping to a file pointer is kind of the point of Allegro 5's filesystem. It's meant to just provide the data for you and abstract the actual interface so that you don't have to care where the data comes from. It could come from a native file, from a ZIP file or even from a completely different filesystem (like a network filesystem, for example) if you provide the interfaces for that. If you want something that maps to a native file pointer, Allegro's file I/O is probably what you want instead of filesystem (and even then that's probably using platform-dependent C file interfaces under the hood, not C++ interfaces).

As for your save function

#SelectExpand
 1g_pUniverse->StoreSector(g_pEnterprise->m_nSectorPositionX,g_pEnterprise->m_nSectorPositionY,g_pEngine);
 2g_pEngine->Save(SaveFile);
 3g_pUniverse->Save(SaveFile);

These are really the functions that matter. I need to see how exactly you write some of that data to the actual file stream to know what goes wrong.

Ariesnl

This is what I have now. But it is not very efficient.
and won't work nice with allegro's file system...
sGameObject is a big struct containing everything a unit (sprite) could have...

#SelectExpand
   1bool TEngine::Save(ofstream & a_SaveStream)
   2{
char szVersion[18]="CURRENT_SECTOR_V1";
  a_SaveStream.write((char*)szVersion,sizeof (szVersion));
   5
   6
std::list<TSprite *>::const_iterator p=m_lstItems.begin();
int m_nObjects = CountSaveObjects();
a_SaveStream.write((char*)&m_nObjects,sizeof (int));
while (p!=m_lstItems.end())
{
      if ( (!(*p)->m_blDestroyed) && ((*p)->m_ID != ID_NONE) && ((*p)->m_ID != ID_SMOKE))
      {
          sGameObject object;
          memset(&object, 0, sizeof(sGameObject));
          object.m_ID = (*p)->m_ID;
          object.m_Member = (*p)->m_Member;
          object.m_dX = (*p)->m_dX;
          object.m_dY = (*p)->m_dY;
          object.m_nZ = (*p)->m_nZ;
          object.m_dAngle = (*p)->m_dAngle;
          object.m_blCanFind = (*p)->m_blCanFind;
          object.m_dSpeed = (*p)->m_dSpeed;
  24
  25
          if ((*p)->m_ID>ID_BULLET_BOTTOM && (*p)->m_ID<ID_BULLET_TOP)
          {
             // sprite is a bullet
             object.m_nLife  = ((TBullet*)(*p))->m_nLife;
             object.m_nCount = ((TBullet*)(*p))->m_nWait;
          }
          else if ((*p)->m_ID>ID_PLANET_BOTTOM && (*p)->m_ID<ID_STAR_TOP)
          {
              // sprite is a planet or a star
  35
          }
  37
          if ((*p)->m_ID == ID_EXPLOSION)
          {
              // sprite is an explosion
              object.m_nLife = ((TExplosion*)(*p))->m_nFrame;
              object.m_nCount = ((TExplosion*)(*p))->m_nWait;
          }
  44
          if ((*p)->m_ID == ID_SMOKE)
          {
              object.m_nLife = ((TSmoke*)(*p))->m_nFrame;
              object.m_nCount = ((TSmoke*)(*p))->m_nWait;
          }
  50
          if (((*p)->m_ID>ID_SHIP_BOTTOM)&&((*p)->m_ID<ID_BASE_TOP))
          {
              //sprite is a ship or a starbase
  54
              object.m_blDocked               = ((TShip *)(*p))->m_blDocked;
              object.m_blDocking              = ((TShip *)(*p))->m_blDocking;
              object.m_blReleasing            = ((TShip *)(*p))->m_blReleasing;
              object.m_blMustBeDestroyed      = ((TShip *)(*p))->m_blMustBeDestroyed;
              object.m_blMustSurvive          = ((TShip *)(*p))->m_blMustSurvive;
  60
              object.m_blMustReachPosition    = ((TShip *)(*p))->m_blMustReachPosition;
              object.m_blDock                 = ((TShip *)(*p))->m_blDock;
              object.m_blNoRelease            = ((TShip *)(*p))->m_blNoRelease;
              object.m_blCanFind              = ((TShip *)(*p))->m_blCanFind;
              object.m_dWaypointX             = ((TShip *)(*p))->m_dWaypointX;
  66
              object.m_dWaypointY             = ((TShip *)(*p))->m_dWaypointY;
              object.m_nTorpedoes             = ((TShip *)(*p))->m_nTorpedoes;
              object.m_nRepairItem            = ((TShip *)(*p))->m_nRepairItem;
              object.m_nCrew                  = ((TShip *)(*p))->m_nCrew;
              object.m_nEnergy                = ((TShip *)(*p))->m_nEnergy;
  72
              object.m_nShieldEnergy          = ((TShip *)(*p))->m_nShieldEnergy;
              object.m_nPhaserEnergy          = ((TShip *)(*p))->m_nPhaserEnergy;
              object.m_nPreferedTarget        = ((TShip *)(*p))->m_nPreferedTarget;
              object.m_nPhaserPower           = ((TShip *)(*p))->m_nPhaserPower;
              object.m_blCanCloak             = ((TShip *)(*p))->m_blCanCloak;
  78
              object.m_blCanFind              = ((TShip *)(*p))->m_blCanFind;
              object.m_blPhaserOn             = ((TShip *)(*p))->m_blPhaserOn;
              object.m_nCloakCharge           = ((TShip *)(*p))->m_nCloakCharge;
              object.m_nCloakCounter          = ((TShip *)(*p))->m_nCloakCounter;
              object.m_nPhotonTimer           = ((TShip *)(*p))->m_nPhotonTimer;
  84
              object.m_nTranslucency          = ((TShip *)(*p))->m_nTranslucency;
              object.m_nTask                  = ((TShip *)(*p))->m_nTask;
              object.m_nCloakState            = ((TShip *)(*p))->m_nCloakState;
  88
              // store health
              for (size_t i=0; i< ((TShip *)(*p))->m_lstHealth.size();i++)
              {
                  object.m_nHealth[(HEALTH)i]=((TShip *)(*p))->m_lstHealth[(HEALTH)i];
              }
  94
              if ((*p)->m_ID==ID_PLAYER)
              {
                  // player specific ! sprite is the player
                  object.m_nSectorPositionX = ((TEnterprise *) (*p))->m_nSectorPositionX;
                  object.m_nSectorPositionY = ((TEnterprise *) (*p))->m_nSectorPositionY;
                  object.m_nWarpFactor      = ((TEnterprise *) (*p))->m_nWarpFactor;
                  object.m_nProbes          = ((TEnterprise *) (*p))->m_nProbes;
              }
          }
 104
          a_SaveStream.write((char*)&object,sizeof (sGameObject));
     }
   ++p;
}
return true;
 110}
 111
 112
 113
 114
 115
 116
 117
 118bool TEngine::Load(ifstream & a_LoadStream)
 119{
Clear(false);
char szVersion[18];
a_LoadStream.read((char *)szVersion,sizeof(char)*18);
 123
int m_nObjects;
a_LoadStream.read((char *)&m_nObjects,sizeof(int));
 126
for (int i=0;i<m_nObjects;i++)
{
     sGameObject object;
     memset(&object, 0, sizeof(sGameObject));
 131
   a_LoadStream.read((char *)&object,sizeof(object));
     TSprite * pSprite=NULL;
 134
   if ((object.m_ID>=ID_CLASS_A)&&(object.m_ID<ID_BLACK_HOLE))
   {
     pSprite = new TSpaceObject(object.m_ID);
 138
   }
   if (object.m_ID == ID_PROBE)
     {
         pSprite = new TProbe(object.m_dX ,
                        object.m_dY,
              object.m_dSpeed,
              object.m_dAngle,
              object.m_nZ,g_pEnterprise);
     }
   else if ((object.m_ID>ID_BULLET_BOTTOM)&&(object.m_ID<ID_BULLET_TOP))
   {
     pSprite = new TBullet( object.m_dX ,
                          object.m_dY,
                object.m_dSpeed,
                object.m_dAngle,
                object.m_nZ,
                object.m_ID,
                object.m_Member);
 157
          ((TBullet *)pSprite)->m_nLife = object.m_nLife;
          ((TBullet *)pSprite)->m_nWait = object.m_nCount;
   }
   else if (object.m_ID == ID_EXPLOSION)
     {
          pSprite = new TExplosion(object.m_dX,
                                   object.m_dY,
                                   object.m_dSpeed,
                   object.m_dAngle,
                   object.m_nZ);
 168
 169
     }
     else if (object.m_ID>ID_SHIP_BOTTOM)
   {
    switch (object.m_ID)
    {
        case ID_PLAYER:
                 {
                      pSprite = new TEnterprise();
                      g_pEnterprise = (TEnterprise *)pSprite;
                      g_pEnterprise->m_nSectorPositionX = object.m_nSectorPositionX;
                      g_pEnterprise->m_nSectorPositionY = object.m_nSectorPositionY;
                      g_pEnterprise->m_nWarpFactor      = object.m_nWarpFactor;
                      g_pEnterprise->m_nProbes          = object.m_nProbes;
                 }
 184
 185
      break;
 187
      case ID_GALAXYCLASS:
                   pSprite = new TFederation_Ship();
 190
      break;
 192
      case ID_KLINGONBC:
        {
          pSprite = new TKlingonBC();
 196
 197
 198
        }
      break;
 201
      case ID_KLINGONBOP:
           {
               pSprite = new TKlingonBOP();
           }
 206
      break;
 208
      case ID_ROMULANBOP:
        {
          pSprite = new TRomulanBop();
 212
 213
 214
        }
      break;
 217
      case ID_FEDERATIONBASE:
      {
            pSprite = new TStarbase(ID_FEDERATIONBASE);
 221
        }
      break;
 224
      case ID_ROMULAN_BASE:
      {
            pSprite = new TStarbase(ID_ROMULAN_BASE);
 228
      }
      break;
 231
 232
      default:
          throw A5Exception("Unknown shiptype");
      break;
 236
 237
    }
 239
    if (pSprite !=NULL)
          {
              // save TShip specific
              ((TShip *)pSprite)->m_nCrew               = object.m_nCrew;
      ((TShip *)pSprite)->m_nRepairItem         = object.m_nRepairItem;
      ((TShip *)pSprite)->m_nTorpedoes          = object.m_nTorpedoes;
      ((TShip *)pSprite)->m_nShieldEnergy       = object.m_nShieldEnergy;
      ((TShip *)pSprite)->m_nPhaserEnergy       = object.m_nPhaserEnergy;
 248
      ((TShip *)pSprite)->m_nPreferedTarget     = object.m_nPreferedTarget;
      ((TShip *)pSprite)->m_nPhaserPower        = object.m_nPhaserPower;
      ((TShip *)pSprite)->m_dWaypointX          = object.m_dWaypointX;
            ((TShip *)pSprite)->m_dWaypointX          = object.m_dWaypointY;
      ((TShip *)pSprite)->m_blDocked            = object.m_blDocked;
 254
      ((TShip *)pSprite)->m_blDocking           = object.m_blDocking;
      ((TShip *)pSprite)->m_blReleasing         = object.m_blReleasing;
      ((TShip *)pSprite)->m_blMustBeDestroyed   = object.m_blMustBeDestroyed;
      ((TShip *)pSprite)->m_blMustSurvive       = object.m_blMustSurvive;
      ((TShip *)pSprite)->m_blMustReachPosition = object.m_blMustReachPosition;
 260
      ((TShip *)pSprite)->m_blNoRelease         = object.m_blNoRelease;
      ((TShip *)pSprite)->m_blCanFind           = object.m_blCanFind;
      ((TShip *)pSprite)->m_blCanCloak          = object.m_blCanCloak;
              ((TShip *)pSprite)->m_blCanFind           = object.m_blCanFind;
              ((TShip *)pSprite)->m_blPhaserOn          = object.m_blPhaserOn;
 266
              ((TShip *)pSprite)->m_nCloakCharge        = object.m_nCloakCharge;
              ((TShip *)pSprite)->m_nCloakCounter       = object.m_nCloakCounter;
              ((TShip *)pSprite)->m_nPhotonTimer        = object.m_nPhotonTimer;
              ((TShip *)pSprite)->m_nTranslucency       = object.m_nTranslucency;
              ((TShip *)pSprite)->m_nTask               = object.m_nTask;
 272
              ((TShip *)pSprite)->m_nCloakState         = object.m_nCloakState;
 274
      for (size_t i=0;i<((TShip *)pSprite)->m_lstHealth.size();i++)
      {
          ((TShip *)pSprite)->m_lstHealth[i]=object.m_nHealth[i];
      }
          }
      }
 281
      if (pSprite !=NULL)
          {
              // save TSprite specific
              pSprite->m_dX              = object.m_dX;
          pSprite->m_dY              = object.m_dY;
          pSprite->m_nZ              = object.m_nZ;
      pSprite->m_dSpeed          = object.m_dSpeed;
      pSprite->m_dAngle          = object.m_dAngle;
              pSprite->m_Member         = object.m_Member;
              pSprite->m_ID             = object.m_ID;
              Add(pSprite);
          }
 294
   }
 296
 297std::list<TSprite *>::const_iterator p=m_lstItems.begin();
 298while (p!=m_lstItems.end())
 299{
if (((*p)->m_ID>ID_SHIP_BOTTOM)&&(((TShip *)(*p))->m_blDocked))
{
  ((TShip *)(*p))->m_blCanFind = false;
  ((TShip *)(*p))->m_blDocking=false;
  ((TShip *)(*p))->m_blReleasing = false;
  ((TShip *)(*p))->m_dSpeed=0;
  ((TShip *)(*p))->m_pBaseTarget=(TShip *) Seekstarbase(((TShip *)(*p))->m_Member,false,100000,((TShip *)(*p))->m_dX,((TShip *)(*p))->m_dY);
  ((TShip *)(*p))->m_pTarget = ((TShip *)(*p))->m_pBaseTarget;
}
else if (((*p)->m_ID>ID_SHIP_BOTTOM)&&(((TShip *)(*p))->m_blDocking))
{
  ((TShip *)(*p))->m_blDocking=true;
  ((TShip *)(*p))->m_blReleasing = false;
  ((TShip *)(*p))->m_pBaseTarget=(TShip *) Seekstarbase(((TShip *)(*p))->m_Member,false,100000,((TShip *)(*p))->m_dX,((TShip *)(*p))->m_dY);
  ((TShip *)(*p))->m_pTarget = ((TShip *)(*p))->m_pBaseTarget;
}
 316
++p;
 318}
 319
 320
 321return true;
 322
 323}

Audric

If you want cross-platform behavior, you need to save your structures one field at a time. Choose an endianness for the file format, and save every multi-byte integer with the specific function for its size (short : 16, long: 32).

al_fwrite16le(saveFile, object.m_dX);
al_fwrite16le(saveFile, object.m_dY);

Same when you reload them :

object.m_dX = al_fread16le(saveFile);
object.m_dY = al_fread16le(saveFile);

Thread #616442. Printed from Allegro.cc