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Simple 2D Target Scanner for Unity
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Simple2DTargetScanner : MonoBehaviour
public float scanFrequency; //in seconds
public float scanRadius = 5; //in world units
private float scanFrequencyCounter = 0; //counter for time between scans
public string[] targetTagArray; //array of tags of GameObjects to include
//delegate event to notify subscribed scripts
public delegate void TargetHit(Transform target);
public event TargetHit OnTargetHit;
public Color editorCircleColor =; //circle colour for editor
public bool scannerEnabled = true; //enable or disable scanner (or you can just enable/disable script if you prefer)
// Update is called once per frame
void FixedUpdate()
//if not enabled, return to stop code below from running.
if (!scannerEnabled)
//counter to track time between scans
scanFrequencyCounter += Time.deltaTime;
//once counter reaches the total time we set between scans, we scan for target and reset counter to zero.
if (scanFrequencyCounter >= scanFrequency)
scanFrequencyCounter = 0;
//using Physics2D we will draw a circle and use a 2d raycast to see what objects are within it.
//Targets must have collider for raycast to return or it won't be detected with this method.
RaycastHit2D[] raycastHit2D = Physics2D.CircleCastAll(this.transform.position, scanRadius, Vector2.right, scanRadius * 2f);
//if we hit any targets, notify listeners that need this info
//make sure to check if OnTargetHit is null or not in case no subscribers (but if no subscribers, why using this at all? ;) )
if (raycastHit2D.Length > 0 && OnTargetHit != null)
for(int i = 0; i < raycastHit2D.Length; i++)
//Important note: if you have a lot of target scanners running at once, for performance it might be better to just scan based on
//layers rather than compare gameobject tags.
for (int t = 0; t < targetTagArray.Length; t++)
if (raycastHit2D[i].transform.CompareTag(targetTagArray[t]))
//delgate event
//break out of both loops after first hit
i = raycastHit2D.Length + 1;
//Unity editor code. Make sure to use hashtag UNITY_EDITOR so this code doesn't compile to non-editor build.
//Draw gizmo wire disc (circle) when GameObject is selected.
//If you want it to always draw, then you can use void OnDrawGizmos() instead
void OnDrawGizmosSelected()
//set gizmo colour.
UnityEditor.Handles.color = editorCircleColor;
//draw wire circle (disc in unity lingo) based on radius variable you set.
UnityEditor.Handles.DrawWireDisc(this.transform.position, this.transform.forward, scanRadius);
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