I need to add a force to an object based on the local vector of the object that is hitting it and not the world coordinates or local coordinates of the object being hit.

Question

I have the following script attached the the "projectile" I thought that the "direction" variable take the vector3 of the owner of the script but it did not. I am a novice and I appreciate any help.`using UnityEngine; using System.Collections;

public class Projectile : MonoBehaviour

{ public float power; private Vector3 direction;

 void OnTriggerEnter(Collider other)
 {
     direction = Vector3.forward;
     other.rigidbody.AddRelativeForce(direction * power);
 }

}`

Thanks!

Answer 1

Answer by Baste · Nov 11, 2014 at 10:14 AM

Vector3.forward is the global forward (Z-axis, (0,0,1)) Vector. If you want the local forward, you need to use the transform's forward, helpfully named transform.forward.

So your code would be:

 void OnTriggerEnter(Collider other)
 {
     direction = transform.forward;
     other.rigidbody.AddRelativeForce(direction * power);
 }

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robertbu · Nov 11, 2014 at 05:21 PM 0

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@Baste - AddRelativeForce() takes a local coordinate, not a world coordinate.

Bunny83 · Nov 11, 2014 at 05:24 PM 0

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That doesn't make much sense ;) AddRelativeForce expects a Vector in local space. transform.forward is actually a worldspace vector. Using it like a localspace vector of another object will result in some strange direction. The solution is to not use localspace at all. Use the normal AddForce and use a worldspace vector like transform.forward of the object you want.

amcgoo · Nov 11, 2014 at 05:27 PM 0

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Thank you Baste I have used transform.forward as you see below and it works pretty well.

    public float power;

    public Transform direction;
 
     void OnTriggerEnter(Collider other)
     {
         Vector3 localForward= power*direction.forward;
         other.rigidbody.AddRelativeForce(localForward);
         Destroy(gameObject, 1f);
     }
 }

this way the force goes with the projectile. thanks again.

I need to add a force to an object based on the local vector of the object that is hitting it and not the world coordinates or local coordinates of the object being hit.

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