How to hide Text that is behind the Main Camera,How to hide Ui elements that are behind the camera

Questions & Answers
1

I’m making a 3D racing game and I attached text to my Ai Player that shows their speed,
This is my code for attaching this text to my Player:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class ClampSpeed : MonoBehaviour {

    public Text label;
    public Rigidbody carRigidbody;
	// Update is called once per frame
	void Update ()
    {
        Vector3 labelPos = Camera.main.WorldToScreenPoint(transform.position);
        label.transform.position = labelPos;
        label.text = carRigidbody.velocity.magnitude.ToString("F0") + " U/S";
        if(carRigidbody.velocity.magnitude > 90)
        {
            label.color = Color.red;
        }
        else
        {
            label.color = Color.white;
        }
    }
}

When the Ai Player is in front of me I can see the text just fine:

But when the Ai Player is behind me the text still appear on screen, which I don’t want

So how do I hide this text if it is behind my main camera? (The main camera is attached to my Player)

,I’m making a 3D racing game and I want the Ai Players to have Text showing their speed,
This is my code for attaching a UI text element to the Ai Player.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class ClampSpeed : MonoBehaviour {

    public Text label;
    public Rigidbody carRigidbody;
	// Update is called once per frame
	void Update ()
    {
        Vector3 labelPos = Camera.main.WorldToScreenPoint(transform.position);
        label.transform.position = labelPos;
        label.text = carRigidbody.velocity.magnitude.ToString("F0") + " U/S";
        if(carRigidbody.velocity.magnitude > 90)
        {
            label.color = Color.red;
        }
        else
        {
            label.color = Color.white;
        }
    }
}

When I look at the Ai Player their tag shows just fine:

But when the Ai Player is behind me…

So how do I hide this Text when the Ai player is behind my Camera? (which is attached to my Player)

2

The z value of result of Camera.main.WorldToScreenPoint(transform.position); will be negative if it’s behind the camera.