Make shiny souls move towards and orbit around the an object.

Soul.lua

function Soul:update(dt)

	local target_x, target_y = self.target_x, self.target_y

	-- do we already have a target?
	if (not target_x) and (not target_y) then
		-- figure out the hook position
		local hook_angle = math.pi*2/(#self.master.souls)*self.index + love.timer.getTime()*3
		target_x = self.master.x + math.cos(hook_angle)*32
		target_y = self.master.y + math.sin(hook_angle)*32
  	end

	-- pull towards hook
	local ddx, ddy = target_x - self.x, target_y - self.y
	self.dx = self.dx + ddx*dt*10
	self.dy = self.dy + ddy*dt*10
	
	-- on target?
	local dist2 = ddx*ddx + ddy*ddy
	if self.onTarget and (dist2 < 25) then
		self:onTarget()
		self.purge = true
	else
		-- update soul position
		GameObject.update(self, dt)
	end
end