C# Convert Vector3[] to Vector2[]

Perhaps using extension methods in combination with Array.ConvertAll will be more close to your needs:

Add this extension to your script:

 public static class MyVector3Extension
 {
     public static Vector2[] toVector2Array (this Vector3[] v3)
     {
         return System.Array.ConvertAll<Vector3, Vector2> (v3, getV3fromV2);
     }
         
     public static Vector2 getV3fromV2 (Vector3 v3)
     {
         return new Vector2 (v3.x, v3.y);
     }
 }

and use it like:

 Vector2[] v2 = v3.toVector2Array ();

Here is an example enclosed:

 using UnityEngine;
 using System.Collections;
 
 public class TestVectorConvert : MonoBehaviour
 {
     // Use this for initialization
     void Start ()
     {
         Vector3[] v3 = new Vector3[5];
         for (int i = 0; i < 5; i++) {
             v3 [i] = new Vector3 (0.5f, 0.4f, 1.0f);
         }
 
         Vector2[] v2 = v3.toVector2 ();
         for (int i = 0; i < 5; i++) {
             Debug.Log (v2 [i].ToString ());
         }
     }
     
     // Update is called once per frame
     void Update ()
     {
     
     }
 }
 
 public static class MyVector3Extension
 {
     public static Vector2[] toVector2 (this Vector3[] v3)
     {
         return System.Array.ConvertAll<Vector3, Vector2> (v3, getV3fromV2);
     }
         
     public static Vector2 getV3fromV2 (Vector3 v3)
     {
         return new Vector2 (v3.x, v3.y);
     }
 }

There probably isn't any so you can do you own:

 Vector2[] ConvertArray(Vector3[] v3){
     Vector2 [] v2 = new Vector2[v3.Length];
     for(int i = 0; i <  v3.Length; i++){
         Vector3 tempV3 = v3[i];
         v2[i] = new Vector2(tempV3.x, tempV3.y);
     }
     return v2;
 }

 

the one liner way using linq library.

   using System.Linq;
          List<Vector3> v3positions = new List<Vector3>();
     
     
            List<Vector2> v2Positions => v3positions.Select((v3) => (Vector2)v3).ToList();