Efficient way to find nearest object with component

Question

Hello,

So as the title suggests, I'm looking for a way to find the nearest object with a certain component that causes the least lag. Using OverlapSphere causes too much lag if there's too many game objects nearby, and this is due to the fact that I use tiny cubes with colliders as blood. (9 in total).

Is there perhaps a better way to fix this lag problem I'm having?

Code for Detection:

 public void senseEnemiesNearby(float radius){
         if (target == null) {
             Collider[] hitColliders = Physics.OverlapSphere(transform.position, radius);
             senseEnemies = true;
             savedLoc = loc;
             Cube cub = GetClosestEnemy (hitColliders, radius);
             if (cub != null) {
                 if (cub.team != team) {
                     setTarget (cub);
                 }
             }
         }
     }
 
     private Cube GetClosestEnemy(Collider[] enemies, float radius)
     {
         Cube cub = null;
         float minDist = radius;
         Vector3 currentPos = transform.position;
         foreach (Collider c in enemies)
         {
             if (c.gameObject != gameObject) {
                 if (c.gameObject.GetComponent<Cube> () != null && c.gameObject.GetComponent<Cube> ().team != team) {
                     Transform t = c.transform;
                     float dist = Vector3.Distance(t.position, currentPos);
                     if (dist < minDist)
                     {
                         cub = c.gameObject.GetComponent<Cube> ();
                         minDist = dist;
                     }
                 }
             }
         }
         return cub;
     }

Thanks HighlordWeaponry

Answer 1

Here are three general performance boosters to your algorithm:

First of all you may want to use layers. OverlapSphere has an additional layermask parameter.
Next you shouldn't use GetComponent more than once per object. Currently you use GetComponent up to 3 times per object. Just create a local variable inside the foreach loop and get the component once.
Finally when sorting objects based on the distance it's faster to compare sqrMagnitude. It of course doesn't tell your the actual distance but the greater than / lower than relation will stay the same.

So do something like this:

 public LayerMask layers;
 
 public void senseEnemiesNearby(float radius)
 {
     if (target == null)
     {
         Collider[] hitColliders = Physics.OverlapSphere(transform.position, radius, layers);
         senseEnemies = true;
         savedLoc = loc;
         Cube cub = GetClosestEnemy (hitColliders, radius);
         if (cub != null)
         {
             setTarget (cub);
         }
     }
 }
 
 private Cube GetClosestEnemy(Collider[] enemies, float radius)
 {
     Cube cub = null;
     float minDist = radius;
     Vector3 currentPos = transform.position;
     foreach (Collider c in enemies)
     {
         if (c.gameObject == gameObject)
             continue;
         Cube cube = c.GetComponent<Cube>();
         if (cube != null && cube.team != team)
         {
             Transform t = c.transform.position - currentPos;
             float dist = t.x*t.x + t.y*t.y + t.z*t.z;  // Same as "= t.sqrMagnitude;" but faster
             if (dist < minDist)
             {
                 cub = cube;
                 minDist = dist;
             }
         }
     }
     return cub;
 }

Note i removed your second team check in your "senseEnemiesNearby" method. Since your "GetClosestEnemy" method can only return an object that has to be on a different team the null check is enough.

How many objects are there in total and how many are usually in range of the OverlapSphere? I doubt that this actually caused much slowdown. Have you used the Profiler to narrow down your bottleneck?

Efficient way to find nearest object with component

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