bullet.lua

function bullet:enterFrame(e)
	if (self.destroied ) then
		self:destroy()
		return true;
	end
	
	--check self is out of screen
	if ( self:isOut() ) then
		self.destroied = true;
		return true;
	end

	--check existence of target
	if ( not utils.existsObject( self.target ) ) then
		self.destroied = true;
		return true;		
	end
	
	--rotate at target
	self.rotation = utils.getAngle( self.x, self.y, self.target.x, self.target.y )

	--calculate distance between self (bullet) and target
	local distance = utils.getDistance( self.x, self.y, self.target.x, self.target.y );
	
	--if it's less than bullet speed then move to point sharp
	if (distance <= self.speed) then
		self.x = self.target.x
		self.y = self.target.y
	else
		--calculate offset
		self.dx = math.cos( math.rad( self.rotation) ) * self.speed;
		self.dy = math.sin( math.rad( self.rotation) ) * self.speed;
		
		--move
		self.x = self.x + self.dx
		self.y = self.y + self.dy
	end
	
	--check collisions between self and enemies
	self:checkCollision()
end