add health controller

Project/Assets/ML-Agents/Examples/FPS_Game/Prefabs/Projectile.prefab

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Project/Assets/ML-Agents/Examples/FPS_Game/Scenes/FPS_Game.unity

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+  currentHealth: 100
+  damagePerHit: 5
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Project/Assets/ML-Agents/Examples/FPS_Game/Scripts/AgentHealth.cs

+using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
-    public float currentHealth;
+    public float currentHealth = 100;
-    public float damagePerHit;
+    public float damagePerHit = 5;
 
     // Start is called before the first frame update
     void Start()
 
     }
 
-
+    private void OnCollisionEnter(Collision col)
+    {
+        if (col.transform.CompareTag("projectile"))
+        {
+            currentHealth -= damagePerHit;
+        }
+    }
 }