Mandelbrot set generator in Lua

generator.lua

return singleton(function()
	local o = {}
	local graphics, surfaces, matrix, bit, complex, color_spaces
	local rad = math.rad

	o.init = function()
	    matrix = math.matrix()
		surfaces = (require 'EngineB/graphics/textures/surface')()
	    graphics = (require 'EngineB/graphics')()
	    complex = require 'utils/complex'
	    bit = require 'bit'
	    color_spaces = (require 'EngineB/graphics/color_spaces')()
	end

	o.quit = function()
	end

	local function genMandelbrot(width, height)
		local mdata = {}
		
		local clamp = function(v, min, max)
			return math.min(math.max(v, min), max)
		end

		local function RGB(r,g,b)
			--print(r,g,b)
			local r,g,b = math.floor(clamp(r, 0, 1.0)*0xFF),math.floor(clamp(g, 0, 1.0)*0xFF),math.floor(clamp(b, 0, 1.0)*0xFF)
			return bit.bor(r, 0x100*g, 0x10000*b)
		end
		local maxIterations = 500

		local function getMBValue(x,y)
			local iterations = 0
			local z = complex {0, 0}
			local c = complex {x, y}
			local sum = complex {0, 0}
			-- y = z^2 + c

			while (z[1]^2 + z[2]^2 < 2*2)  and (iterations < maxIterations) do
				z = z^2 + c
				iterations = iterations + 1 
			end

			local i = 200
			v = math.log((iterations+i)/(maxIterations+i) + 1.0)

			return v
		end

		local vmin, vmax = math.huge, 0
		
		for y=1,height do
			for x=1,width do
				local pos = (y-1)*height + x - 1
				local rx,ry = (x-1)/width, (y-1)/height
				-- <-2, 0.25>
				local x0 = rx*3.0 - 2.0
				local y0 = ry*2.0 - 1.0

				local v = getMBValue(x0, y0)
				if v < vmin then
					vmin = v
				end
				if v > vmax then
					vmax = v
				end

				local clampedV = clamp(v, 0, 1.0)

				mdata[pos+1] = RGB(color_spaces.hsl2rgb(clamp(0.7 - clampedV*2.2, 0, 1.0), 1.0, clamp(0.6 - clampedV, 0, 1)))
			end
		end

		print(vmin, vmax)

		local data = {}
		for i=1, (width*height) do
			local rgb = mdata[i]
			data[i] = bit.tobit(0xFF000000 + rgb)
		end
		return data
	end

	o.mandelbrot = function(texture, width, height)
		local pixelformat = graphics.pixelFormat(SDL.PIXELFORMAT_ABGR8888, true)
		local surface = surfaces.new(width, height, pixelformat)

		surface.update(genMandelbrot(width, height))
		texture.update(0,0, width, height, surface)
	end

	return o
end)