Drawing a box around a world object transform postion via canvas screen overlay

Hi Guys,

I am working on a targeting system for a little fun project i am making, I would like it to display a "image" cross hair on my overlay canvas around an object depended on there position in the world. Currently i have it half working, where i can track a enemy's ship but the issue is i only want it to be tracked if it is with in the Camera's current FOV. Right now it will show up if its directly behind me or in front of me, where i just want it to show when it's in front of me with in the FOV of the camera.

This is what i have so far

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.UI;
5.  
6. public class CanvasBox : MonoBehaviour {
7.  
8.     public Transform FollowThis;
9.     public PlayerInfo pi;
10.     public Image image;
11.  
12.     private void Start()
13.     {
14.    
15.         //Don't show on load.
16.         image.enabled = false;
17.     }
18.  
19.     void Update()
20.     {
21. //If the player currently has a target
22.         if (pi.GetHasTarget())
23.         {
24. //set the enemys target to the transform to track
25.             FollowThis = pi.GetTarget().transform;
26. //enable the image (might be bad practice to do in a update loop)  Should add to player controller bool check targeted later.
27.             image.enabled = true;
28. //if there is a target.
29.             if (FollowThis == null)
30.             {
31.                 return;
32.             }
33. //Get the vector 2 of the position of the enemy via world space
34.             Vector2 sp = Camera.main.WorldToScreenPoint(FollowThis.position);
35. //edit the transform to match the world postion
36.             this.transform.position = sp;
37.         }
38.     }
39.  
40. //setter of if it has a target
41.     public void NoTarget()
42.     {
43.         image.enabled = false;
44.     }
45. //make sure there is a game object in our hierarchy selected
46.     void OnEnable()
47.     {
48.         if (gameObject.activeInHierarchy)
49.         {
50.             Update();
51.         }
52.     }
53. }
54.  

effectively it will show if either its directly in front of me or behind me and track it's movements. I presume this is simple but i am having a bit of a block at the moment. Presume it will be something like.

//Sudo Code
If Camera.fov has Target in its view.. then show image, else don't.

Thanks in advance!

 

Ow my bad i got it, just realized what i was doing wrong, I should also have been checking the Z axis to see if it was >= 0, to see if it was in front or behind me.

if (Camera.main.WorldToViewportPoint(FollowThis.position).z >= 0)
{
//In front of the camera!
}

Thanks anyway guys.

 

If you want additional insight on this topics I suggest looking up quill18creates selecting units on YouTube.

 

Thanks for the suggestion, I made a few improvements to my system if you would like to see it let me know, added the ability to track target's off screen etc.

Here is a little clip of where i got to with it today, just messing around a bit for fun