chroma_solstice/_helpers.lua

function constrain(val, low, high)
	if val > high then 
		return high
	elseif val < low then 
		return low
	else 
		return val
	end
end

function map(value, inMin, inMax, outMin, outMax)
	local inPercent = value / (inMax - inMin)
	return (outMax - outMin) * (inPercent) + outMin
end

function lerp(a, b, amount)
	return (1 - amount) * a + (amount * b)
end

local function sourceRoots()
	local roots = {}
	local seen = {}
	local function add(root)
		if type(root) == "string" and root ~= "" and not seen[root] then
			table.insert(roots, root)
			seen[root] = true
		end
	end
	add("/home/happy/code/chroma_solstice")
	if love and love.filesystem then
		if love.filesystem.getSource then add(love.filesystem.getSource()) end
	end
	return roots
end

local function readFromRoot(root, relPath)
	local file = io.open(root .. "/" .. relPath, "r")
	if not file then return nil end
	local contents = file:read("*a")
	file:close()
	return contents
end

local function pathExists(path)
	local file = io.open(path, "r")
	if file then
		file:close()
		return true
	end
	return false
end

-- Write to the project tree itself (not LÖVE's save dir) so edits persist in the
-- repo during dev. Packaged games still fall back to love.filesystem.write.
function writeToSource(relPath, contents)
	for _, base in ipairs(sourceRoots()) do
		local path = base .. "/" .. relPath
		local file, err = io.open(path, "w")
		if file then
			file:write(contents)
			file:close()
			print("Saved source: " .. path)
			return true
		end
		print("Save source failed: " .. path .. " (" .. tostring(err) .. ")")
	end
	print("Save failed: did not write fallback for " .. relPath)
	return false
end

-- The editor occasionally needs to rename a source level after it has written
-- the replacement.  Keep that operation alongside writeToSource so packaged
-- games still fall back to LÖVE's writable save directory.
function removeFromSource(relPath)
	for _, base in ipairs(sourceRoots()) do
		local path = base .. "/" .. relPath
		local file = io.open(path, "r")
		if file then
			file:close()
			return os.remove(path)
		end
	end
	return love.filesystem.remove(relPath)
end

-- Runtime saves live in LÖVE's write directory.  This deliberately uses only
-- love.filesystem operations: they cannot delete files from the source tree.
function clearRuntimeSaveData(roomName)
	local removed = 0
	if roomName then
		-- love.filesystem.remove only affects the writable save directory, never
		-- the shipped/source room with the same path.
		if love.filesystem.remove("rooms/" .. roomName .. ".sav") then removed = 1 end
		return removed
	end

	local function removeTree(path)
		local info = love.filesystem.getInfo(path)
		if info and info.type == "directory" then
			for _, child in ipairs(love.filesystem.getDirectoryItems(path)) do
				removeTree(path .. "/" .. child)
			end
		end
		if love.filesystem.remove(path) then removed = removed + 1 end
	end

	-- These are the only files this game writes through love.filesystem: room
	-- autosaves and the generated asset cache. Source levels are read-only to
	-- this API and cannot be removed here.
	removeTree("rooms")
	if love.filesystem.remove("assets.prop") then removed = removed + 1 end
	return removed
end

-- Read from the project tree directly so a stale copy in LÖVE's save directory
-- can't shadow the real source file. This mirrors writeToSource's root order.
function readFromSource(relPath)
	for _, base in ipairs(sourceRoots()) do
		local contents = readFromRoot(base, relPath)
		if contents then return contents end
	end
	return love.filesystem.read(relPath)
end

function getSourceDirectoryItems(relPath)
	for _, base in ipairs(sourceRoots()) do
		local dir = base .. "/" .. relPath
		if pathExists(dir) then
			local ok, proc = pcall(io.popen, "find " .. string.format("%q", dir) .. " -maxdepth 1 -mindepth 1 -printf '%f\n'")
			local items = {}
			if ok and proc then
				for item in proc:lines() do table.insert(items, item) end
				proc:close()
			end
			return items
		end
	end
	return love.filesystem.getDirectoryItems(relPath)
end

-- Cached image loader. The filesystem is the source of truth for art, so every
-- sprite is loaded on demand by path (deduped here) rather than from a
-- hand-maintained central table.
local spriteCache = {}
function loadSprite(path)
	if not spriteCache[path] then
		spriteCache[path] = love.graphics.newImage(path)
	end
	return spriteCache[path]
end

function cellShapeFromBox(box)
	local cells = {}
	for i = 1, box.w do
		for j = 1, box.h do
			table.insert(cells, {x = i, y = j})
		end
	end
	return cells
end

-- Which 16x16 cells of an image are non-empty, for multi-cell collision
-- shapes. LÖVE 11 no longer exposes Image:getData(), so inspect ImageData
-- directly instead of creating a GPU Image first.
function getCellsFromSprite(spritePath)
	local img = love.image.newImageData(spritePath)
	local w, h = img:getWidth(), img:getHeight()
	local box = {w = w / 16, h = h / 16}
	local boxCells = cellShapeFromBox(box)
	if box.w < 1 or box.h < 1 then
		return boxCells
	end

	local cellsToRemove = {}

	for _, cell in pairs(boxCells) do
		local startPixel = {x = (cell.x - 1) * 16, y = (cell.y - 1) * 16}
		local endPixel = {x = (cell.x * 16) - 1, y = (cell.y * 16) - 1}
		local empty = true

		for i = startPixel.x, endPixel.x do
			for j = startPixel.y, endPixel.y do
				local r, g, b, a = img:getPixel(i, j)
				if a > 0 and (r > 0 or g > 0 or b > 0) then
					empty = false
				end
			end
		end

		if empty then
			cellsToRemove[cell] = cell
		end
	end

	local i = 1
	while i <= #boxCells do
		if boxCells[i] == cellsToRemove[boxCells[i]] then
			table.remove(boxCells, i)
		else
			i = i + 1
		end
	end

	return boxCells
end