I am creating a top-down shoot-em-up game where the player is stationary turrets. Enemy come from the top of the screen at random speed (sine movement). I created some obstacle like stones, bunkers so enemy will not be an easy target. the location of obstacle will be changed at random every 5-10 minutes. However enemies ignore all obstacle. They overlap everything.
I have to set every thing to solid and give every enemy the 8-way movement, but this cause the problem. Only 1 high speed enemy, 1 big heavy enemy and 1 bunker, the system is noticeably slow down. (I am planing to have around 8-10 enemies on the screen at a time.) Moreover, the movement when colliding is wired. Sometime they move down around the object, sometime they circle through the back try to reach the apex of sin wave, but they never stop at the collision and converse the course.
So I am not sure that this method is correct or not. Should I use physic or pathfinding instead?