koobas.hobune.stream
Moving an object left and right
Hi all, I'm trying to get an object to move left to a certain point and then once it reaches that point it moves right until a certain point.
I've got the object to move left, but can't get it to move right as it seems to freeze once it's reached the position I want.
void Update () {
transform.Translate(Vector3.left * speed * Time.deltaTime);
if (transform.position.x <= -4)
{
transform.Translate(Vector3.right * speed * Time.deltaTime);
Debug.Log("Working!");
}
The object goes left, and reaches to -4 on the x Axis but then freezes and doesn't move, any ideas?
Thanks!
that's because your first translate had never ignored. furthermore, it makes more sense you declare one speed, starting negative and once the left end condition is met you change the speed to positive until the opposite condition is met.
Think how this method works, step by step:
1. move the object left
2. check if reached the target on the left
3. if yes, then move the object right
So, when your object reaches the target spot on the left, you're moving it both left and right at the same time, in result not moving it at all.
Add a flag to check whether you're still moving left or right, then based on its value move in the direction you want:
private bool movingLeft;
void Start() {
movingLeft = true;
}
void Update() {
if (movingLeft == true) {
// move left
if (transform.position.x <= -4) movingLeft = false;
} else {
// move right
}
}
Looks like we gave the same solution at the same time lol. The performance addict in me makes me point out that using bools for this and an extra if is rather wasteful. A float comparison is not so slow as to need to only occur conditionally, and in the meantime you might get mispredictions and lose a few precious nanoseconds.
Obviously this isn't super important or anything, you would never really see that slowdown, I'm mostly just have a hyperactive olfactory sense when it comes for sniffing out micro-optimizations.
Yeah, nice ti$$anonymous$$g! :) I wrote it this way to not complicate the code more than needed to get a basic solution to the problem. I'm guessing it will be rewritten multiple times to fit the changing needs of the game anyway.
The issue here is that, when you do reach -4, you nudge it to the right and then you're no longer
//Up at the top with your variables:
private Vector3 dir = Vector3.left;
//Your Update function
void Update(){
transform.Translate(dir*speed*Time.deltaTime);
if(transform.position.x <= -4){
dir = Vector3.right;
}else if(transform.position.x >= 4){
dir = Vector3.left;
}
}
The important things to note here are:
The direction persists between frames. It only changes in very specific cases
It's generally a good idea to only do 1 translate call per frame and store your direction in a variable anyway. Explicitly setting the direction and speed is much more predictable and you always know why something moves the way it does.
I'm assuming you wanted it going from -4 to 4, although really you should store these in variables. Firstly, you can see these in the inspector, but secondly, the numbers -4 and 4 on their own don't mean anything on their own. On the other hand, 'leftExtent' and 'rightExtent' might be -4 and 4, but are much more meaningful and, if you use these extents for other things, you don't have to change these magic numbers everywhere.
