Folder structure

assets/Scripts/Game/Unit/Enemy/EnemyMover/EnemyMover.ts

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+import { Node } from "cc";
+import { Enemy } from "../Enemy";
+
+export abstract class EnemyMover {
+    protected targetNode: Node;
+    protected enemies: Enemy[] = [];
+
+    public constructor(targetNode: Node) {
+        this.targetNode = targetNode;
+    }
+    public addEnemy(enemy: Enemy): void {
+        this.enemies.push(enemy);
+    }
+
+    public removeEnemy(enemy: Enemy): void {
+        const index: number = this.enemies.indexOf(enemy);
+        if (index != -1) {
+            this.enemies.splice(index, 1);
+        }
+    }
+
+    public abstract gameTick(deltaTime: number): void;
+}

assets/Scripts/Game/Unit/Enemy/EnemyMover/EnemyMover.ts.meta

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+{
+  "ver": "4.0.23",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "179f7bfa-44fc-4f41-9432-4aec4f3991a6",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}

assets/Scripts/Game/Unit/Enemy/EnemyMover/FollowTargetEnemyMover.ts

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+import { Vec3 } from "cc";
+import { EnemyMover } from "./EnemyMover";
+
+export class FollowTargetEnemyMover extends EnemyMover {
+    public gameTick(deltaTime: number): void {
+        this.enemies.forEach((enemy) => {
+            let direction: Vec3 = new Vec3();
+            direction = Vec3.subtract(direction, this.targetNode.worldPosition, enemy.node.worldPosition);
+            enemy.moveBy(direction.normalize(), deltaTime);
+        });
+    }
+}

assets/Scripts/Game/Unit/Enemy/EnemyMover/FollowTargetEnemyMover.ts.meta

@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.23",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "20a3f56b-402d-4639-9629-c90f70f55206",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}

assets/Scripts/Game/Unit/Enemy/EnemyMover/WaveEnemyMover.ts

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+import { Vec3 } from "cc";
+import { Enemy } from "../Enemy";
+import { EnemyMover } from "./EnemyMover";
+
+export class WaveEnemyMover extends EnemyMover {
+    private enemyToDirection: Map<Enemy, Vec3> = new Map<Enemy, Vec3>();
+    private lastTargetPosition: Vec3 = new Vec3();
+    private lastDirection: Vec3 = new Vec3();
+
+    public addEnemy(enemy: Enemy): void {
+        let direction: Vec3 = new Vec3();
+
+        // if the enemy is added soon enough, move as a single group towards one direction
+        if (Vec3.distance(this.lastTargetPosition, this.targetNode.worldPosition) < 10) {
+            direction = this.lastDirection;
+        } else {
+            direction = Vec3.subtract(direction, this.targetNode.worldPosition, enemy.node.worldPosition);
+            this.lastDirection = direction;
+            this.lastTargetPosition = this.targetNode.worldPosition.clone();
+        }
+
+        this.enemyToDirection.set(enemy, direction.normalize());
+        super.addEnemy(enemy);
+    }
+
+    public removeEnemy(enemy: Enemy): void {
+        this.enemyToDirection.delete(enemy);
+        super.removeEnemy(enemy);
+    }
+
+    public gameTick(deltaTime: number): void {
+        for (const enemyAndDirection of this.enemyToDirection) {
+            enemyAndDirection[0].moveBy(enemyAndDirection[1], deltaTime);
+        }
+    }
+}

assets/Scripts/Game/Unit/Enemy/EnemyMover/WaveEnemyMover.ts.meta

@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.23",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "5215f6f3-855e-4d8e-afad-80915ca7b2f2",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}