Quickly added Enemy_4

Assets/__Scripts/Enemy_4.cs

@@ -2,17 +2,66 @@ 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
 {
-    // Start is called before the first frame update
+    [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;
+            }
+        }
     }
 
-    // Update is called once per frame
-    void Update()
-    {
-        
+    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
     }
 }

Assets/__Scripts/Weapon.cs

@@ -0,0 +1,34 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+/// <summary>
+/// This is an enum of the various possible weapon types.
+/// It also includes a "shield" type to allow a shield power-up.
+/// Items marked [NI] below are Not Implemented in the IGDPD book.
+/// </summary>
+
+public enum WeaponType {
+    none,       // The default / no weapon
+    blaster,    // A simple blaster
+    spread,     // Two shots simultaneously
+    phaser,     // [NI] Shots that move in waves
+    missile,    // [NI] Homing missiles
+    laser,      // [NI]Damage over time
+    shield      // Raise shieldLevel
+}
+
+public class Weapon : MonoBehaviour
+{
+    // Start is called before the first frame update
+    void Start()
+    {
+        
+    }
+
+    // Update is called once per frame
+    void Update()
+    {
+        
+    }
+}

Assets/__Scripts/Weapon.cs.meta

@@ -0,0 +1,11 @@
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