height_map = {}

function height_map.toNormalMap(heightMap, strength)
	local imgData = heightMap:getData()
	local imgData2 = love.image.newImageData(heightMap:getWidth(), heightMap:getHeight())
	local red, green, blue, alpha
	local x, y
	local matrix = {}
	matrix[1] = {}
	matrix[2] = {}
	matrix[3] = {}
	strength = strength or 1.0

	for i = 0, heightMap:getHeight() - 1 do
		for k = 0, heightMap:getWidth() - 1 do
			for l = 1, 3 do
				for m = 1, 3 do
					if k + (l - 1) < 1 then
						x = heightMap:getWidth() - 1
					elseif k + (l - 1) > heightMap:getWidth() - 1 then
						x = 1
					else
						x = k + l - 1
					end

					if i + (m - 1) < 1 then
						y = heightMap:getHeight() - 1
					elseif i + (m - 1) > heightMap:getHeight() - 1 then
						y = 1
					else
						y = i + m - 1
					end

					local red, green, blue, alpha = imgData:getPixel(x, y)
					matrix[l][m] = red
				end
			end

			red = (255 + ((matrix[1][2] - matrix[2][2]) + (matrix[2][2] - matrix[3][2])) * strength) / 2.0
			green = (255 + ((matrix[2][2] - matrix[1][1]) + (matrix[2][3] - matrix[2][2])) * strength) / 2.0
			blue = 192

			imgData2:setPixel(k, i, red, green, blue)
		end
	end

	return love.graphics.newImage(imgData2)
end

return height_map