OpenEuphoria

1. Tile-Based Map Editor Dilemma

• Posted by Aen Aen <Fist1000 at AOL.COM> Nov 07, 1998
• 358 views

Hey Euphorians,

Here's a puzzle for you:

I'm working on an option for tile-based map editor to import an image, chop it
up into tiles, and create a map layer with it. The catch is, I need it to be
able to eliminate duplicate tiles in the tile bay while still maintaining the
'visual order' of the map. This is something that proves useful for people
importing snapshots from console emulators and the like.

It's in mode 19 and all the tiles are 16x16, stored sequentially in one large
array. Something like this:

  integer numtiles
  numtiles = 100

  atom vsp -- tile bay
  vsp = allocate(256 * numtiles)

The map data is stored similarly:

  integer mapwide, mapdeep
  mapwide = 100
  mapdeep = 100

  atom map
  map = allocate(mapwide * mapdeep)

Each byte in the map data is basically an index to the appropriate tile to
display from the tile bay. So, given a tile index, you'd find its starting
point in the tile bay by doing something like: map + (tile * 256).

At the moment I basically just load in the image, and divide the dimensions by
16 to get the number of whole tiles that I can extract along the width and
height. Then I create a temporary tile bay that's (width * height * 256) bytes
and patch all the whole tiles into the temporary tile bay. Then I just destroy
and reallocate the layer and stuff in all the tiles from the temporary tile
bay on after the other. I figured that might somehow be simpler than checking
for duplicates while grabbing from the image? It's all just a muddle in my
brain. :)

I'm unsure how to create a list of unique tile indexes and then go about
removing duplicates without disrupting things. For example, if I delete all
the duplicates of one tile from the tilebay, the tile indexes in the map data
that were correct before are then rendered incorrect. I'd need to adjust the
indexes, of course, but I find it very difficult to solve.

If you need further information, go right ahead and ask. I'm coding this in C,
but I intend on porting it over to EUPHORIA after it's all finished. For fun,
and for the learning experience.

You don't necessarily need to throw an entire coded solution at me, I just
need a little direction as to how I get from point A to point B without a
hernia. :)

Thanks,
aen