Omnimaga

General Discussion => Technology and Development => Computer Programming => Topic started by: Munchor on October 22, 2011, 02:06:01 pm

Title: Reading tilemap algorithm
Post by: Munchor on October 22, 2011, 02:06:01 pm

I have an issue that's been annoying me for some time now. I have to read a file to an bi-dimensional array.

The file looks like this:

Code: [Select]

1111111111111111111111111
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1000000000000000000000001
1111111111111111111111111

I am using the C library ('stdio.h') to read the file, and this is what I have so far.

Code: [Select]

int map[26][24];
int map_width = 26;
int map_height = 24;
int x;
int y;
FILE *map_file = fopen("map.txt", "r");
for (x = 0; x < map_width; x++)
{
  for (y = 0; y map_height; y++)
  {
     fscanf(map_file, "%d", &map[x][y]);
  }
  fscanf(map_file, "\n"); // Skip newlines
}

However, it doesn't really seem to be working, since I'm printing the array right after and it doesn't look like the file:

Code: [Select]

for (x = 0; x < map_width; x++)
{
  for (y = 0; y < map_height; y++)
  {
    printf("%d", map[x][y]);
  }
}

Thanks for the help!

Title: Re: Reading tilemap algorithm
Post by: Scipi on October 22, 2011, 02:13:18 pm

Are you casting to an int after you read from the file? Because that might be the problem.

In Daemons I read from a binary file and I read to a memblock equal to the size of the file - 2 bytes for size data.

I then copy that memblock to a vector for use in the game. ;)

Perhaps you could try that. (Is this only going to be C or C++?)

EDIT: Here's my code:

Code: [Select]

fstream map;
    string map_path;//Holds the path to the files

    try
    {


        map_path = "data/maps/visual/" + mapID;

        map.open(map_path.c_str(), ios::in|ios::binary);
        char memblock[2];
        //char* mapblock;
        if(map.is_open())
        {
            //memblock = new char [2];
            //map.seekg(0, ios::beg);
            map.read(memblock, 2);

            MapWidth = memblock[0];
            MapHeight = memblock[1];
            //delete[] memblock;
            char mapblock[MapWidth * MapHeight];
            MapData.resize(MapWidth * MapHeight);
            //map.seekg(2, ios::beg);
            map.read(mapblock, MapWidth * MapHeight);
            for(int i = 0; i < (MapWidth * MapHeight); i++)
                MapData[i] = (int)mapblock[i];
            //cout << MapData[0];
            //cout << map_path.c_str();

            map.close();
        }

}
    catch(exception& e)
        {cout << e.what() << "\n";}
    return;


Title: Re: Reading tilemap algorithm
Post by: Munchor on October 22, 2011, 02:18:58 pm

Quote from: HOMER-16 on October 22, 2011, 02:13:18 pm

Are you casting to an int after you read from the file? Because that might be the problem.

In Daemons I read from a binary file and I read to a memblock equal to the size of the file - 2 bytes for size data.

I then copy that memblock to a vector for use in the game. ;)

Perhaps you could try that. (Is this only going to be C or C++?)

EDIT: Here's my code:

Code: [Select]

fstream map;
    string map_path;//Holds the path to the files

    try
    {


        map_path = "data/maps/visual/" + mapID;

        map.open(map_path.c_str(), ios::in|ios::binary);
        char memblock[2];
        //char* mapblock;
        if(map.is_open())
        {
            //memblock = new char [2];
            //map.seekg(0, ios::beg);
            map.read(memblock, 2);

            MapWidth = memblock[0];
            MapHeight = memblock[1];
            //delete[] memblock;
            char mapblock[MapWidth * MapHeight];
            MapData.resize(MapWidth * MapHeight);
            //map.seekg(2, ios::beg);
            map.read(mapblock, MapWidth * MapHeight);
            for(int i = 0; i < (MapWidth * MapHeight); i++)
                MapData[i] = (int)mapblock[i];
            //cout << MapData[0];
            //cout << map_path.c_str();

            map.close();
        }

}
    catch(exception& e)
        {cout << e.what() << "\n";}
    return;


Actually, the program is C++, but I thought C would be better for this, due to speed and size issues, I want map loading to be fast.

What do you mean by "Are you casting to an int after you read from the file? Because that might be the problem."?

Title: Re: Reading tilemap algorithm
Post by: Scipi on October 22, 2011, 02:23:44 pm

You are reading from a text file, so what you are reading is going to be a char data type. However, the array is an int so there's going to be issues there. I use the code:

Code: [Select]

MapData[i] = (int)mapblock[i];

to fix that in my file loading as it changes the char to an int. (Also, the function posted above is quite fast, speed won't be a problem between C/C++) ;)

Title: Re: Reading tilemap algorithm
Post by: lkj on October 22, 2011, 02:26:46 pm

It should be

Code: [Select]

int map[24][26]; instead of your

Code: [Select]

int map[26][24];.
Also there's a typo: for (y = 0; y < map_height; y++)
And I think you have to exchange the x and the y loop.
Correct me if I'm wrong.