PICO-8 load maps from strings

map-strings.p8

-- For this I whipped up my good ol’ reliable approach of having the following functions:
-- export the currently drawn map to the clipboard
-- I used this in copied .p8 files to draw levels,
-- run them and copy the given string into this main
-- file's map collection
function export_map()
    -- start with empty string
    local mapString = ""
    -- loop over the map tile by tile
    -- and append tile numbers by , after each other
    -- this will give back a string similar to what
    -- you can see later in the map collection
    for x=0,15 do
   	 for y=0,15 do
   		 mapString = mapString..mget(x,y)..","
   	 end
    end
    -- paste the string onto the clipboard
    printh(mapString, '@clip')
end

-- With this you can setup a collection inside init that is holding all your map string one by-one.

map_collection = {
   	 "0,0,0,0,0,0,36,0,0,21,18,45,14,18,47,14,0,36,0,0,0,0,0,0,0,21,61,18,18,45,18,18,0,0,0,1,19,14,14,0,0,0,5,5,18,18,14,14,0,0,0,2,12,19,18,0,36,0,0,0,18,18,18,18,0,0,0,14,19,62,18,0,0,0,0,4,18,18,61,18,0,37,0,62,19,19,18,0,0,0,21,18,45,18,18,47,0,0,0,2,19,14,18,0,0,0,21,18,47,18,45,18,0,0,0,14,19,14,18,0,0,0,21,18,18,18,18,14,0,0,0,2,19,19,18,0,0,36,21,18,14,18,18,18,0,0,0,2,14,19,18,0,0,0,21,18,18,18,18,61,0,36,0,45,19,19,14,0,0,0,21,18,14,18,14,18,0,0,0,2,14,30,18,0,0,0,6,18,14,14,18,18,0,0,0,3,45,19,14,0,0,21,18,14,18,18,14,14,0,0,0,0,0,0,0,0,0,21,18,18,18,61,18,14,0,0,0,0,0,0,0,0,0,21,47,18,18,45,18,14,0,0,37,0,0,0,0,36,0,21,18,18,14,18,18,18,",
   	 "0,0,0,0,0,0,36,0,0,21,18,45,14,18,47,14,0,36,0,0,0,0,0,0,0,21,61,18,18,45,18,18,0,0,0,0,0,0,0,0,0,0,5,5,18,18,14,14,0,0,0,18,18,30,14,0,36,0,0,0,18,18,18,18,0,0,0,2,14,2,14,0,0,0,0,4,18,18,61,18,0,37,0,2,12,2,18,0,0,0,21,18,45,18,18,47,0,0,0,14,19,19,14,0,0,0,21,18,47,18,45,18,0,0,0,0,0,0,0,0,0,0,21,18,18,18,18,14,0,0,0,0,36,0,0,0,0,36,21,18,14,18,18,18,0,0,0,0,0,0,0,0,0,0,21,18,18,18,18,61,0,36,0,14,14,18,30,0,0,0,21,18,14,18,14,18,0,0,0,14,2,14,2,0,0,0,6,18,14,14,18,18,0,0,0,2,12,18,62,0,0,21,18,14,18,18,14,14,0,0,0,14,19,45,18,0,0,21,18,18,18,61,18,14,0,0,0,0,0,0,0,0,0,21,47,18,18,45,18,14,0,0,37,0,0,0,0,36,0,21,18,18,14,18,18,18,",
 }

-- The long strings basically contain every tile of the first screen (0,0) - (15,15)
-- where we draw all our maps (the very first one screen region of the map-editor).
-- Having this string your only need is to setup a level variable and then the following two functions:

-- load map from a string. This string is stored in map-collection
-- and mapIndex is the passed level counter number.
function load_map(mapIndex)

    -- fetch the mapIndex-th element of the map collection
    local mapString = map_collection[mapIndex]
    -- init x,y
    local x,y = 0,0
    -- split the fetched string into numbers, so now it is {1,2,3,4,5} array
    -- instead of "1,2,3,4,5" string
    for tileId in all(split(mapString,",")) do
   	 -- iterate through each tileId (1,2,34, etc..)
   	 -- and handle them correctly
   	 -- the only tiles which we use as specials
   	 -- are gonna be the spirits = 12
   	 -- the mushrooms and the flips for the mushrooms
   	 if tileId == SPIRIT_TILE then
   		 -- if it is a spirit, spawn one on the coords
   		 -- and reset the tile to a grass (entities)
   		 -- I draw with sprites instead of tiles
   		 add_character(x, y)
   		 mset(x, y, 18)
   	 elseif tileId == MUSHROOM_ON_TILE then
   		 -- spawn a grown mushroom
   		 add_mushroom(x, y, true)
   		 mset(x, y, 18)
   	 elseif tileId == MUSHROOM_OFF_TILE then
   		 -- spawn an ungrown mushroom
   		 add_mushroom(x, y, false)
   		 mset(x, y, 18)
   	 else
   		 -- just set the tile accordingly
   		 mset(x, y, tileId)
   	 end
   	 -- iterate y first because most double for
   	 -- cycles read in as column by column
   	 y+=1
   	 if y > 15 then
   		 y = 0
   		 x += 1
   	 end
    end
end

-- The pair of this function is the unload, that handles deleting everything you do
-- not want to bring over to the new stage, which are usually the actors, particles.

function unload_map()
    -- empty all the arrays
    character = {}
    particleCollection = {}
    mushroomCollection = {}
    -- reset all the tiles on the
    -- screen
    for x=0,15 do
   	 for y=0,15 do
   		 mset(x,y,0)
   	 end
    end
end

-- With this all setup we just need to modify our code a little bit. 
-- When you win a stage, instead of going to the menu, we unload the map,
-- add one to the level counter, call load_map(level) and set the state to game so we can play again!

-- I now can duplicate my .p8 files, so I have level_1.p8, level_2.p8,
-- draw the according level in the cart, run it (as export is run during _init()
-- in my case but you can do it in button press) and paste the new string into my map_collection.
-- And bam, as many levels as you can fit into the string limit!

More PICO-8 Tutorials: https://github.com/Achie72/kofi-articles/blob/main/README.md#pico-8-tutorials