Find all objects inside box collider

Question

Hello, how to make table with all objects inside box collider which is trigger, alternatively find the nearest one? I tried something like this:

   private void OnTriggerStay(Collider[] col)

but Collider[] does not work with OnTriggerStay

Answer 1

Answer by hexagonius · Apr 27, 2018 at 04:40 PM

If you want to know that at a certain point in time, just use an OverlapBox:
https://docs.unity3d.com/ScriptReference/Physics.OverlapBox.html

Add comment · Show 1 · Share

Wenon · Apr 27, 2018 at 07:31 PM 0

Share

I need object with box collider because rotation and scale and position of collider are dynamic in my project and I need to see this box does it work as it should

Answer 2

Answer by Harinezumi · Apr 27, 2018 at 12:31 PM

This is not necessarily the best solution, but the simplest that comes to my mind: when a Collider enters a trigger that has this script, it is added to a list, when it exits, it is removed from the list. You can get the current list by calling GetColliders() (just don't modify the contents):

 public class ColliderContainer : MonoBehaviour {
 
     private List<Collider> colliders = new List<Collider>();
     public List<Collider> GetColliders () { return colliders; }
 
     private void OnTriggerEnter (Collider other) {
         if (!colliders.Contains(other)) { colliders.Add(other); }
     }
 
     private void OnTriggerExit (Collider other) {
         colliders.Remove(other);
     }
 
 }

Add comment · Show 5 · Share

TreyH · Apr 27, 2018 at 04:20 PM 0

Share

@Wenon did this work for you?

Wenon TreyH · Apr 27, 2018 at 07:28 PM 0

Share

Yes, it works, I found this earlier but I thought there is simpler way

Chrism24747 · Sep 27, 2020 at 11:54 PM 0

Share

It worked thank you so much

zosichd · Aug 06, 2021 at 01:37 PM 0

Share

but what if this collider was turned off all this time, and when I turn it on, I already need this list?

rage_co zosichd · Aug 06, 2021 at 01:56 PM 0

Share

OnTriggerStay is what you're looking for....just simply do this...

 void OnTriggerStay(Collider other)
 {
   if(!colliders.Contains(other))
   {
     colliders.Add(other);
   }
 }

this will also check if the object is already in list so there shouldn't be duplication problems either....hope this helps

Answer 3

Answer by timothygao8710 · Mar 02, 2021 at 04:16 AM

Adding on the Harinezumi, a HashSet can be used rather than a list, which would yield a lower time complexity(make your code run faster). While the .Remove() and .Contains() method for List runs in O(N^2) and O(N) respectively, the .Remove() and .Contains() for HashSet are both O(1). This can make a huge difference if you're dealing with many objects. Also the code is simpler:

 public class ColliderContainer : MonoBehaviour {
  
      private HashSet<Collider> colliders = new HashSet<Collider>();
 
      public HashSet<Collider> GetColliders () { return colliders; }
  
      private void OnTriggerEnter (Collider other) {
          colliders.Add(other); //hashset automatically handles duplicates
      }
  
      private void OnTriggerExit (Collider other) {
          colliders.Remove(other);
      }
  
  }

Add comment · Share

Answer 4

First one tells whether Vector3 point resides within the BoxCollider.

Second one gives all Collider[] within the BoxCollider using a layer mask.

 ///<summary>
 ///returns true if the point is within our BoxCollider
 ///</summary>
 public static bool IsWithinBoxBounds(Vector3 point, BoxCollider boxCollider) {
      point = boxCollider.transform.InverseTransformPoint( point ) - boxCollider.center;
      
      float halfX = (boxCollider.size.x * 0.5f);
      float halfY = (boxCollider.size.y * 0.5f);
      float halfZ = (boxCollider.size.z * 0.5f);
      if( point.x < halfX && point.x > -halfX && 
         point.y < halfY && point.y > -halfY && 
         point.z < halfZ && point.z > -halfZ )
          return true;
      else
          return false;
 } //end func IsWithinBoxBounds

 ///<summary>
 ///returns all colliders within BoxCollider
 ///</summary>
 public static Collider[] BoxColliderOverlaps(BoxCollider target, int layerMask, bool hitTriggers) {

     return Physics.OverlapBox(target.transform.position + target.center, target.size * 0.5f, target.transform.rotation, layerMask, hitTriggers ? QueryTriggerInteraction.Collide : QueryTriggerInteraction.Ignore);
 
 } //end func BoxColliderOverlaps

Find all objects inside box collider

4 Replies

Your answer

Follow this Question

Related Questions