Pixel Projectiles

ID:1306462
 
Jun 28 2013, 3:46 pm (Edited on Jun 28 2013, 3:52 pm)
(See the best response by Magnum2k.)
Code:
// Credit: Lummox JR
atom/var/Owner
atom/movable/proc/PixelMove(dx, dy)
    var/d = 0
    if(dx) d |= (dx>0) ? EAST : WEST
    if(dy) d |= (dy>0) ? NORTH : SOUTH
    if(abs(dx) >= abs(dy)*2) d &= 3
    else if(abs(dy) >= abs(dx)*2) d &= 12
    Move(loc, d, step_x+dx, step_y+dy)

atom/movable
    projectiles
        parent_type = /obj
        var dx
        var dy
        var speed = 1

        Ball
            icon = 'Effects.dmi'
            icon_state = "Ball"

            New(var/atom/movable/_owner, var/atom/loc, var/atom/clicked)
                src.loc = loc
                src.step_x = (64 - _owner.bound_width) / 2
                src.step_y = _owner.step_y
                src.Owner = _owner

                var/dx = clicked.x - _owner.x
                var/dy = clicked.y - _owner.y

                var/r = sqrt(dx * dx + dy * dy)

                var/vx = dx / r * speed
                var/vy = dy / r * speed

                for(var/i in 1 to 30)
                    src.PixelMove(dx+vx, dy+vy)
                    sleep(world.tick_lag)
                del(src)

            Crossed(var/atom/movable/target_crossed) //this doesn't work.
                del(target_crossed)
                if(src.Owner == target_crossed) return 1
                // src.collide_with(target_crossed)

atom/movable/Click(location, control, params)
    if(!location) return
    new/atom/movable/projectiles/Ball(usr, usr.loc, location)


Problem description: The projectile isn't firing in the right angle. If you fire on the tile right below you, the projectile will be slowly moving to the left. Offsetting is all wrong. This is my first pixel projectile attempt, and it's difficult.
Jun 28 2013, 4:27 pm (Edited on Jun 28 2013, 7:31 pm)
Best response
You could get the angle between the two vectors, which would be the owner's position and the target's(the tile you clicked) position. Once the angle between the two vectors is established, you can then fire the projectile in that angle. The formula for finding the angle is arccos(u * v / magnitude(u) * magnitude(v)), where u and v are vectors--in your case, it would be the owner's position and the target's position.

Or, if you don't want to go through that, you can just use Fireking's pixel projectiles implementation. Your current method isn't actually getting the angle, it's just getting the distance between the two atoms, which you can already do using get_dist() and bounds_dist(), so I'm not entirely sure why you redefined it.