Simple Perception System (Unity, C#)

Here is a very simple perception C# code that I used my lecture today for Unity.

Function that can be added to the Enemy class to check if the enemy sees the player object or not (the code for other functionality can be found on the post /2011/10/29/intro-to-gameplay-programming-with-unity/). With this code, an enemy can perceive player object farther away if the player object is front and when rear on the side perseption range is more limited.There is also very simple line-of-sight checking functionality.

The features of the perception system can be controlled via class variables

public float frontRange = 10.0f;
public float frontAngle = 30.0f; // if angle between forward and los is less than this, the target is at front
public float closeRange = 2.0f;

Then the function actually handling the if enemy can see the player object or not.

public bool IsPlayerWithinPerceptionRange()  {
   RaycastHit hit;
   bool playerWithinPerceptionRange = false;
   if(Physics.Linecast(transform.position, GameAgents.GetPlayer().transform.position, out hit)) {
        if(hit.transform == GameAgents.GetPlayer().transform) {
            if(hit.distance <= closeRange) {
                 playerWithinPerceptionRange = true;
                 Debug.DrawLine(transform.position, hit.transform.position,;
            else if(hit.distance <= frontRange) {
                 if(Vector3.Angle(transform.forward,hit.transform.position - transform.position) <= frontAngle) {
                     playerWithinPerceptionRange = true;
                     Debug.DrawLine(transform.position, hit.transform.position,;

    return playerWithinPerceptionRange;

One thought on “Simple Perception System (Unity, C#)

  1. Pingback: Perception System Explained « Beyond Skin

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