How are maps stored?

[Tissemand]

In the most basic sense, how are maps stored for UO?
I'm trying to write a program to render maps using C, and UltimaSDK is way out of my head to even concentrate on.

 

[Jeff]

http://www.fallingdownstairs.net/uo/maps.html

 

[Tissemand]

http://www.fallingdownstairs.net/uo/maps.html

OH. Thanks and bookmarked that site!

 

[Tissemand]

Am I doing this correctly (sorta pseudocoded in C#)?

            BinaryReader reader = new BinaryReader(File.Open(@"\Program Files (x86)\EA Games\Ultima Online 2D Client\map0.mul", FileMode.Open));

            while (reader.BaseStream.CanRead)
            {
                Block block;
                block.header = reader.ReadInt32();
                block.cells = new Cell[8,8];
                for( int i = 0; i < 8; i++ )
                {
                    for ( int j = 0; j < 8; j++ )
                    {
                        block.cells[i, j].tileId = reader.ReadInt16();
                        block.cells[i, j].z = reader.ReadSByte();
                    }
                }
            }
            reader.Close();

Then to get the image, I should just search up each block tile id's on the land art?

 

[Jeff]

Looks right, but testing it is the only way you will find out for sure.

 

[Tissemand]

How are the CellY and CellX calculated?

 

[Jeff]

How are the CellY and CellX calculated?

Please explain more.... i have no idea what you are talking about, what calculation?

 

[Tissemand]

Please explain more.... i have no idea what you are talking about, what calculation?

Looking at: http://www.fallingdownstairs.net/uo/maps.html

From there, the offset to a certain cell is:
((CellY * 8) + CellX) * 3

 

[Jeff]

Block:
int header; // Unknown
Cells...
Each block contains 64 cells, treated as an 8x8 matrix loaded left to right, top to bottom.

so

for(int x = 0; x < 8; x++)
for(int y = 0; y < 8; y++)
{
    int cellX = x;
    int cellY = y;
}

EDIT: You had that code already

                for( int i = 0; i < 8; i++ )
                {
                    for ( int j = 0; j < 8; j++ )
                    {
                        block.cells[i, j].tileId = reader.ReadInt16();
                        block.cells[i, j].z = reader.ReadSByte();
                    }
                }

 

[Tissemand]

so

for(int x = 0; x < 8; x++)
for(int y = 0; y < 8; y++)
{
    int cellX = x;
    int cellY = y;
}

EDIT: You had that code already

                for( int i = 0; i < 8; i++ )
                {
                    for ( int j = 0; j < 8; j++ )
                    {
                        block.cells[i, j].tileId = reader.ReadInt16();
                        block.cells[i, j].z = reader.ReadSByte();
                    }
                }

Bah, I meant, if I have the character's coords, (and I fseek to the proper block) how can I get the position in the block?

 

[Jeff]

To get the block they are on, take player x,y and divide by 8.
To get the cell within the block, take player x,y modulus of 8.

 

[Tissemand]

To get the block they are on, take player x,y and divide by 8.
To get the cell within the block, take player x,y modulus of 8.

d'oh, thanks. I feel dumb now.

 

[Jeff]

d'oh, thanks. I feel dumb now.

Don't feel dumb, we all have our moments

 

[Tissemand]

There seems to be something odd happening:

I tried seeking to 123x123, and it gave me item ids ranging from 3-6, with z's of 0.
Do you see anything that's wrong by chance?

maps.c

Block getBlock( FILE * file, uint32_t x, uint32_t y, uint32_t block_height )
{
  long filePos = ((x * block_height) + y) * 196;
  Block block;

  fseek( file, filePos, SEEK_SET );
  getNextBlock( file, &block );

  return block;
}

void getNextBlock( FILE * mapFile, Block * block )
{
  int i, j;
  //Block block;

  // read 32 bits
  fread( &(block->header), sizeof(int32_t), 1, mapFile );

  // loop through to fill the 8x8 matrix
  for( i = 0; i < 8; i++ )
  {
    for( j = 0; j < 8; j++ )
    {
      // read 16 bits, and use htons to fix endian issue
      int16_t tile;
      fread( &tile, sizeof(int16_t), 1, mapFile );
      (block->cells[i][j].tileId) = htons( tile );

      // read 8 bits
      fread( &(block->cells[i][j].z), sizeof(int8_t), 1, mapFile );
    }
  }
}

main.c

      Block block = getBlock( mapFile, 123, 123, 512 );
      int i, j;
      for( i = 0; i < 8; i++ )
      {
        for( j = 0; j < 8; j++ )
        {
          printf( "%i %i", block.cells[i][j].tileId, block.cells[i][j].z );
        }
      }