kill dead code

_helpers.lua

@@ -45,3 +45,67 @@ function readFromSource(relPath)
 	end
 	return love.filesystem.read(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 a sprite are non-empty, for multi-cell collision shapes.
+function getCellsFromSprite(sprite)
+	local w, h = sprite:getWidth(), sprite: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 img = sprite:getData()
+	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