Check if player is in front of enemy?

Question

I have a script that checks whether the player is in line of sight of an enemy using raycasting, however I always want to only return true if the player is in front of the enemy. How would I do that.

Answer 1

Best Answer

Answer by Eric5h5 · Apr 26, 2010 at 04:39 PM

See this answer, except use Z instead of X.

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StephanK · Apr 26, 2010 at 04:43 PM 0

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That's even easier... ;)

DESTRUKTORR · Aug 01, 2012 at 01:58 AM 0

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That resource is no longer available. Would you $$anonymous$$d directing me to an updated location?

Eric5h5 · Aug 01, 2012 at 02:19 AM 0

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Updated link.

Judgeking · May 11 at 08:23 AM 0

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code from link:

 var otherTransform : Transform;
 ...
 ...
 function Start () {
     var relativePoint = transform.InverseTransformPoint(otherTransform.position);
     if (relativePoint.x < 0.0)
         print ("Object is to the left");
     else if (relativePoint.x > 0.0)
         print ("Object is to the right");
     else
         print ("Object is directly ahead");
 }

Answer 2

Answer by StephanK · Apr 26, 2010 at 04:42 PM

Calculate the angel between your forward vector and the enemy position. If absolute value is bigger than a certain threshold (eg. 90 degrees) it's behind you. To do that there a some very convenient functions:

Vector3 directionToTarget = transform.position - enemy.position;
float angel = Vector3.Angel(transform.forward, directionToTarget);
if (Mathf.Abs(angel) > 90)
    Debug.Log("target is behind me");

Not tested but should work.

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Eric5h5 · Apr 26, 2010 at 11:13 PM 2

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I totally wish there was a Vector3.Angel function. :)

StephanK · Apr 27, 2010 at 05:56 AM 0

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Well, sometimes even wishes come true... http://unity3d.com/support/documentation/ScriptReference/Vector3.Angle.html

Eric5h5 · May 30, 2010 at 04:00 AM 1

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@spree: a month late, but: no, that did not make my wish come true. Read again, more carefully. ;)

StephanK · May 31, 2010 at 02:27 PM 0

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Lol. I see it now... ;)

mrCrush · Oct 19, 2017 at 08:18 PM 0

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Thank you! It helped a lot!

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Answer 3

Answer by asimov · Jun 25, 2012 at 02:54 PM

I know it's been a month since any comments were left on this, but posting as the link in the answer no longer works. So regarding spree 1's code above, for complete 360 degree detection, I think it should be;

     if (Mathf.Abs(angel) > 90 && Mathf.Abs(angel) < 270)
         Debug.Log("target is in front of me"); 

     if (Mathf.Abs(angel) < 90 || Mathf.Abs(angel) > 270)
         Debug.Log("target is behind me");

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Answer 4

Answer by CollosalChris · Aug 06, 2017 at 06:03 AM

Check out InverseTransformPoint as mentioned, but placing code here for better reference:

 public Transform cam;
 public Vector3 cameraRelative;

 void Start()
 {
     cam = Camera.main.transform;
     Vector3 cameraRelative = cam.InverseTransformPoint(transform.position);

     if (cameraRelative.z > 0)
         print("The object is in front of the camera");
     else
         print("The object is behind the camera");
 }

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florinel2102 · Jun 21, 2020 at 03:11 PM 0

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For people who doesn't work as expected , try to adjust (ins$$anonymous$$d of cameraRelative.z > 0 to do something like this cameraRelative.z > 0.15f ) .

Check if player is in front of enemy?

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