math.randomseed(os.time())

local MOONS = {}
local t_moon = nil
for i = 1, 10 do
	local color = {math.random(200),math.random(100),math.random(200)}
	local moon = {500+math.random(400)-200,200+math.random(400)-200,math.random(10)+1,color}
	table.insert(MOONS, moon)
	if moon[2] > 50 and (not t_moon or math.random()>0.5) then
		t_moon = moon
	end
end

local function generate_planet_canvas ()
	local canvas = love.graphics.newCanvas()
	local shader = love.graphics.newShader([[
		vec4 effect( vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords )
        {
            vec4 texcolor = Texel(texture, texture_coords);
			if (color.r == 0.8 && color.g == 1 && color.b == 0.5) {
				float dist = sqrt(pow(screen_coords.x-500, 2)+pow(screen_coords.y-100, 2));
				return vec4(0.8, 1, 0.5, 1) * min(1, 0.05*(208-dist));
			} else if (color.r == 1 && color.g == 1 && color.b == 1 && screen_coords.y<100 && (pow(screen_coords.x-500, 2)+pow(screen_coords.y-100, 2) < 200*200)) {
				return vec4(0, 0, 0, 0);
			} else {
            	return texcolor * color;
			}
        }
	]])
	love.graphics.setCanvas(canvas)
	love.graphics.setShader(shader)
		love.graphics.setColor(255*0.8,255*1,255*0.5,255)
		love.graphics.circle("fill", 500, 100, 200)
		love.graphics.setColor(255,255,255,50)
		for i = 1, 40 do
			love.graphics.ellipse("line", 500, 125, 300-i, 50-i*1/6 )
		end
		for _, moon in ipairs(MOONS) do
			love.graphics.setColor(moon[4])
			love.graphics.circle("fill",moon[1],moon[2],moon[3])
		end
	love.graphics.setShader()
	love.graphics.setCanvas()
	return canvas
end

--------------------------------------------------------------------------------

local PLANET = generate_planet_canvas()

local SCREENS = {}

SCREENS[1] = function (t)
	t = t * 0.1
	love.graphics.draw(PLANET)

	love.graphics.setColor(255,255,255,255)
	love.graphics.circle("fill", 400*(1-t)+t_moon[1]*t, 600*(1-t)+t*t_moon[2], math.min(0, 50*(t-1)))
end

local screen_id = 1
local time = 0

--------------------------------------------------------------------------------

function love.load ()

end

function love.update (dt)
	time = time + dt
end

function love.draw ()
	SCREENS[screen_id](time)
end