space-shmup/Assets/__Scripts/Enemy_4.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// Enemy_4 will start offscreen and then pick a random point on screen to
///   move to. Once it has arrived, it will pick another random point and
///   continue until the player has shot it down.
/// </summary>

[System.Serializable]
public class Part {
    // These three fields need to be defined in the Inspector pane
    public string name;
    public float health;
    public string[] protectedBy;
    [HideInInspector]
    public GameObject go;
    [HideInInspector]
    public Material mat;
}

public class Enemy_4 : Enemy
{
    [Header("Set in Inspector: Enemy_4")]
    public Part[] parts;
    private Vector3 p0, p1; // The two points to interpolate
    private float timeStart; // Birth time for this Enemy_4
    private float duration = 4; // Duration of movement

    void Start()
    {
        // There is already an initial position chosen by Main.SpawnEnemy()
        //  so add it to points as the initial p0 & p1
        p0 = p1 = pos;
        InitMovement();
        Transform t;
        foreach(Part prt in parts) {
            t = transform.Find(prt.name);
            if (t != null) {
                prt.go = t.gameObject;
                prt.mat = prt.go.GetComponent<Renderer>().material;
            }
        }
    }

    void InitMovement() {
        p0 = p1; // Set p0 to the old p1
        // Assign a new on-screen location to p1
        float widMinRad = bndCheck.camWidth - bndCheck.radius;
        float hgtMinRad = bndCheck.camHeight - bndCheck.radius;
        p1.x = Random.Range(-widMinRad, widMinRad);
        p1.y = Random.Range(-hgtMinRad, hgtMinRad);
        // Reset the time
        timeStart = Time.time;
    }
    public override void Move() {
        // This completely overrides Enemy.Move() with a linear interpolation
        float u = (Time.time - timeStart) / duration;
        if (u >= 1) {
            InitMovement();
            u = 0;
        }
        u = 1 - Mathf.Pow(1 - u, 2); // Apply East Out easing to u
        pos = (1 - u) * p0 + u*p1; // Simple linear interpolation
    }
}