DamageScript

Question

Why does this script only work with a rigidbody? And how can I make it work without a rigidbody? I don't want to use a rigidbody because my AI reacts poorly when a rigidbody is attached.

 var hitPoints = 100.0;
 function ApplyDamage (damage : float) 
 {
     if (hitPoints <= 0.0)
         return;
         
     hitPoints -= damage;
     if (hitPoints <= 0.0) 
     {
         BroadcastMessage ("Detonate");
     }
 }
 
 function Detonate () 
 {
     Destroy(gameObject);
 }

Rocket Launcher Script

 var projectile : Rigidbody;
 var initialSpeed = 20.0;
 var reloadTime = 0.5;
 var ammoCount = 20;
 private var lastShot = -10.0;
 var damage = 5.0;
 
 function Fire () 
 {
     var direction = transform.TransformDirection(Vector3.forward);
     var hit : RaycastHit;
     
     // Did the time exceed the reload time?
     if (Time.time > reloadTime + lastShot && ammoCount > 0) 
     {
         // create a new projectile, use the same position and rotation as the Launcher.
         var instantiatedProjectile : Rigidbody = Instantiate (projectile, transform.position, transform.rotation);
             
         // Give it an initial forward velocity. The direction is along the z-axis of the missile launcher's transform.
         instantiatedProjectile.velocity = transform.TransformDirection(Vector3 (0, 0, initialSpeed));
 
         // Ignore collisions between the missile and the character controller
         Physics.IgnoreCollision(instantiatedProjectile.collider, transform.root.collider);
         
         lastShot = Time.time;
         ammoCount--;
     }
 }

Rocket Script

 // The reference to the explosion prefab
 var explosion : GameObject;
 var timeOut = 3.0;
 
 // Kill the rocket after a while automatically
 function Start () {
     Invoke("Kill", timeOut);
 }
 
 
 function OnCollisionEnter (collision : Collision) {
     // Instantiate explosion at the impact point and rotate the explosion
     // so that the y-axis faces along the surface normal
     var contact : ContactPoint = collision.contacts[0];
     var rotation = Quaternion.FromToRotation(Vector3.up, contact.normal);
     Instantiate (explosion, contact.point, rotation);
 
     // And kill our selves
     Kill ();    
 }
 
 function Kill () {
     // Stop emitting particles in any children
     var emitter : ParticleEmitter= GetComponentInChildren(ParticleEmitter);
     if (emitter)
         emitter.emit = false;
 
     // Detach children - We do this to detach the trail rendererer which should be set up to auto destruct
     transform.DetachChildren();
         
     // Destroy the projectile
     Destroy(gameObject);
 }

Answer 1

In the FPS tutorial the explosion prefab that is instantiated when the rocked hits any collider, its script searches for rigidbodys near it so the forces can be applied to them, if there is any rigidbody near it, then it applies force and then it calls for ApplyDamage function in them. The reason why your enemy cube is not destroyed when you fire the rocket is because its not a rigidbody.

To solve the problem do this :

tag all the enemies as "enemy" using the tag manager

in the script attached to the explosion prefab, there are these statements

  for (var hit in colliders) {
         if (!hit)
             continue;
         
         if (hit.rigidbody) {   
             hit.rigidbody.AddExplosionForce(explosionPower, explosionPosition, explosionRadius, 3.0);
                         
             var closestPoint = hit.rigidbody.ClosestPointOnBounds(explosionPosition);
             var distance = Vector3.Distance(closestPoint, explosionPosition);
 
             // The hit points we apply fall decrease with distance from the hit point
             var hitPoints = 1.0 - Mathf.Clamp01(distance / explosionRadius);
             hitPoints *= explosionDamage;
 
             // Tell the rigidbody or any other script attached to the hit object 
             // how much damage is to be applied!
             hit.rigidbody.SendMessageUpwards("ApplyDamage", hitPoints, SendMessageOptions.DontRequireReceiver);
         }

Here you can see that there are 2 if statements , they are : if(!hit) AND if(hit.rigidbody). Add these statements inside the for loop along with them.

 if(hit.gameObject.tag == "enemy"){
     hit.gameObject.SendMessageUpwards("ApplyDamage", hitPoints, SendMessageOptions.DontRequireReceiver);
 
 }

This makes sure that ApplyDamage function is called in enemies that are without rigidbody components.

Hope this helps! Tell me if you have any problems.

DamageScript

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