Arrow = Entity:New(x,y)

 function Arrow:New(x,y,rotation,speed)
 	local o = Entity:New(x,y)

 	o.pos = {x = x, y = y}
  o.speed = speed or 0
  o.sprite_rotation = rotation or 0
  o.vel = {
    x = o.speed * math.cos(o.sprite_rotation),
    y = o.speed * math.sin(o.sprite_rotation)
  }
	o.sprite_offset = {x = 13, y = 1}
  o.stuck = false

 	setmetatable(o, self)
 	self.__index = self
  table.insert(LoadedEntities,o)
 	return o
 end

function Arrow:Smart()

end

function Arrow:HandleAnimation()
  self:LoadAnimation(animation.kupo.arrow)
end

function Arrow:DoPhysics()
   -- horizontal collisions
  if not isThereAnyCollisionAt(self.pos.x + self.vel.x, self.pos.y) then
  	self.pos.x = self.pos.x + self.vel.x
  else
    while not isThereCollisionAt(self.pos.x + math.sign(self.vel.x), self.pos.y) do
      self.pos.x = self.pos.x + math.sign(self.vel.x)
    end
    self.stuck = true
  end
    -- vertical collision
  if not isThereAnyCollisionAt(self.pos.x, self.pos.y + self.vel.y) then
    self.pos.y = self.pos.y + self.vel.y
  else
    while not isThereCollisionAt(self.pos.x, self.pos.y + math.sign(self.vel.y)) do
      self.pos.y = self.pos.y + math.sign(self.vel.y)
    end
    self.stuck = true
  end
  -- stuck into collisions
  if self.stuck then
    --lets allow the arrow to tip a bit into the thing
    self.pos.x = self.pos.x + self.vel.x / 5
    self.pos.y = self.pos.y + self.vel.y / 5
    self.vel.x = 0
    self.vel.y = 0
  end
end