world = world or nil
camera = camera or nil

function init()
	-- Set the title of the main window
	Window.set_title("Hello world!")

	-- Create world and camera
	world = Device.create_world()
	local camera_unit = World.spawn_unit(world, "camera")
	camera = Unit.camera(camera_unit, "camera")
	Camera.set_orthographic_metrics(camera, 0, 0, 1280, 720)
end

function update(dt)
	-- Advance the simulation
	World.update(world, dt)

	-- Stop the engine when the 'ESC' key is released
	if Keyboard.button_released(Keyboard.ESCAPE) then
		Device.quit()
	end
end

function render(dt)
	-- Render the world
	Device.render_world(world, camera)
end

function shutdown()
	-- Cleanup
	Device.destroy_world(world)
end

function g_physics_callback(args)
	-- Do nothing
end