Pico-8 aiming at target proof of concept

I'm working on creating enemies that aim at the player and shoot in my current game project next so I put together this little proof of concept to make sure I understood how to do it. 

You can check out the current release of the project this poc was made for here:  https://eschmiel.itch.io/pov-there-is-a-bug-in-your-house

The poc is interative. Arrow keys move the target and 'z' shoot a projectile at it.

I'm posting all of the code for this project below but you can also look at it in this github repo: https://github.com/eschmiel/aiming-proof-of-concept---pico8

Follow me on Twitter: https://x.com/eschmiel

function _init()
    origin = {30,30}
    target = {80,80}
    vector = get_vector(origin,target)
    calc_target = {
        origin[1]+vector[1],
        origin[2]+vector[2]
       }
    unit_vector = get_unit_vector(vector)
    projectiles={}
end
function _update()
    vector = get_vector(origin,target)
    calc_target = {
        origin[1]+vector[1],
        origin[2]+vector[2]
    }
    unit_vector = get_unit_vector(vector)
    for p in all(projectiles) do
        p:update()
    end
    if(btnp(4)) mk_projectile()
    if(btn(0)) target[1]-=1
    if(btn(1)) target[1]+=1
    if(btn(2)) target[2]-=1
    if(btn(3)) target[2]+=1
end
function _draw()
    cls()
    rectfill(
        origin[1],
        origin[2],
        origin[1],
        origin[2],
        8
    )
    rectfill(
        target[1],
        target[2],
        target[1],
        target[2],
        7
    )
    print('origin: '..origin[1]..', '..origin[2],
    10,70)
    print('target: '..target[1]..', '..target[2],
    10,80)
    print('vector: '..vector[1]..', '..vector[2],
    10,90)
    print('calculated target: '..calc_target[1]..', '..calc_target[2],
    10,100)
    print('unit vector to target: ',
    10,110)
    print(unit_vector[1]..', '..unit_vector[2],
    10,120)
    for p in all(projectiles) do
        p:draw()
    end
end
function get_vector(o,t)
    return {t[1]-o[1],t[2]-o[2]}
end
function get_unit_vector(v)
    magnitude = sqrt(v[1]*v[1] + v[2]*v[2])
    return {v[1]/magnitude, v[2]/magnitude}
end
function mk_projectile()
    local v = get_vector(origin,target)
    local uv = get_unit_vector(v)
    add(projectiles,
        {
            speed=2,
            x=origin[1],
            y=origin[2],
            direction=uv,
            update=function(self)
                self.x+=self.direction[1]*self.speed
                self.y+=self.direction[2]*self.speed
            end,
            draw=function(self)
                rectfill(self.x,self.y,self.x,self.y,9)
            end
        }
    )
end