C# How to destroy instantiated objects after a certain distance?

Currently, I have a top down view of my player character with the main camera following said character. I can instantiate multiple shots from my character, but I don't know how to destroy them after a certain distance. Can someone point me in the right direction? I don't want to use box collider attached to the main camera trick because if the camera moves, so will the box collider and the shots will never hit the collider/exit the collider trigger.

 

Code (CSharp):

1. Vector3 v_dir = projectile.transform.position - character.transform.position;
2. if (v_dir.sqrMagnitude > maxDistance * maxDistance) {
3.    Destroy(projectile);
4. }

You might not want to do it every frame, so maybe
execute this every few frames

 

This code was inserted into my projectile's script and it didn't do anything. Same thing for my firing script. Could you explain what is going on? Why maxDistance * maxDistance?

 

You need to fill in what the projectile is and what the character is for this code to work. Generally you can't just copy code into your project from the forum and have it magically work.

maxDistance * maxDistance is used because it is compared to v_dir.sqrMagnitude, or the Square Magnitute of the vector. Square root operations are expensive so some people avoid it by comparing the squares of values.

 

Yes, like Zaladur says , square root operations are expensive, so this is why we use squared times
directly.

You can give a value to maxDistance - its the distance beyond which you want the projectile
to go boom.