PICO-8 Sliding Movement for PPJJGG

movement.p8

-- function to add characters to the game
-- at any point on the map
function add_character(_x, _y)
	local p = {
		x = _x,
		y = _y,
		direction = 5,
		doReplaceOldTile = false,
		replaceTileId = 0
	}
	-- set it's tile to the player tile
	mset(p.x, p.y, 4)
	-- add it to the collection
	add(characters, p)
end

function _init()

	-- have a direction table that shows how to move 
	-- on x and y to get to the next tile in said direction
	-- it is always mapped to the buttons, so 0 is left, 1 is right
	-- 2 is up, 3 is down, 4 is neutral
	directionTable = {
		{-1, 0}, {1, 0}, {0, -1}, {0, 1}, {0, 0}
	}
	characters = {}
	add_character(4,4)
	add_character(10,4)
	add_character(4,10)
	add_character(10,10)
end

function _update()
	-- check movement for each character
	for i=1,#characters do
		update_player(i)
	end
end

function update_player(_index)
	local character = characters[_index]

	-- save pressed direction for character
	-- only count if the character is already stopped
	if character.direction == 5 then
		if btnp(0) then character.direction = 1 end
		if btnp(1) then character.direction = 2 end
		if btnp(2) then character.direction = 3 end
		if btnp(3) then character.direction = 4 end
	end

	-- see if next tile in that direction is walkable
	local nextTile = mget(character.x + directionTable[character.direction][1], character.y + directionTable[character.direction][2])

	-- if it is not empty void
	-- move the character there
	-- 0 is void, 2 is wall for now
	if (nextTile != 0) and (nextTile != 2) and (nextTile != 4) then
		local oldPosX, oldPosY = character.x, character.y
		local newPosX, newPosY = character.x + directionTable[character.direction][1], character.y + directionTable[character.direction][2]
		-- if the player was on a normal tile, reset it to that (1)
		-- if the player was on a directional tile and has it's replace
		-- flag set, then fetch the directional tile that I need to replace
		-- this is what will preserve the arrow tiles instead of just replacing them with
		-- normal empty tiles
		local tileToReset = character.doReplaceOldTile and character.replaceTileId or 1
		-- if I have fetched the new reset tile, then turn off the flag for it
		if tileToReset != 1 then character.doReplaceOldTile = false end
		
		-- move the character
		character.x, character.y = newPosX, newPosY
		-- check if new tile is redirectional
		if (nextTile > 47) and (nextTile < 52) then
			-- arrow tiles are 48,49,50,51
			-- if I substract 47 then I conver the
			-- tileId to the direction it represents
			character.direction = nextTile - 47

			-- set the flag so the character remembers to set it back
			character.doReplaceOldTile = true
			-- save what needs to be reset
			character.replaceTileId = nextTile
		end
		-- reset the tile the character was on
		mset(oldPosX, oldPosY, tileToReset)
		-- this is what sets the character
		mset(newPosX, newPosY, 4)
	else
		-- if movement is not possible do to void(0), wall(2) 
		-- or another player(4) then stop movement
		character.direction = 5
	end

end

function _draw()
	cls()
	map()
	for character in all(characters) do
		--print("웃", character.x*8, character.y*8, 7)
	end
end

Made for: https://ko-fi.com/post/PPJJGG-1--The-basics-of-the-basics-C0C4ZGCAL