How to show a trigger only when pointing to it directly? - unity3d

Question

I created a transparent cube trigger and I placed it in front of closed doors, so whenever the player walks near the door a message appears saying "this door is locked".
However, I want the message to be gone whenever the player is Not pointing to the door. currently, it shows even when I turn around, the player needs to walk away from the door to make the message disappear.
Here is my code:
public class DoorsTrigger : MonoBehaviour
{
public GameObject partNameText;
private void OnTriggerEnter(Collider other)
{
if (other.CompareTag("Player"))
{
partNameText.SetActive(true);
}
}
private void OnTriggerExit(Collider other)
{
if (other.CompareTag("Player"))
{
partNameText.SetActive(false);
}
}
}
How can I modify it to achieve my goal?

Answer 1

Here is a simple example using Vector3.Angle() to get the direction the player is facing relative to that trigger.
public class DoorsTrigger : MonoBehaviour
{
public GameObject partNameText;
private void OnTriggerEnter(Collider other)
{
if (other.CompareTag("Player"))
{
//Assuming 'other' is the top level gameobject of the player,
// or a child of the player and facing the same direction
Vector3 dir = (this.transform.position - other.gameObject.transform.position);
//Angle will be how far to the left OR right you can look before it doesn't register
float angle = 40f;
if (Vector3.Angle(other.gameObject.transform.forward, dir) < angle) {
partNameText.SetActive(true);
}
}
}
private void OnTriggerExit(Collider other)
{
//Make sure the text is actually showing before trying to disable it again
if (other.CompareTag("Player") && partNameText.activeSelf)
{
partNameText.SetActive(false);
}
}
}
Alternatively, you can keep your trigger mostly as is, and do a ray cast from the player to see if they are looking at the door.
//Put this snippet in a function and call it inside the player's Update() loop
RaycastHit hit;
Ray ray = new Ray(this.transform.position, this.transform.forward);
if(Physics.Raycast(ray, out hit))
{
//Tag the gameObject the trigger is on with "Door"
if(hit.collider.isTrigger && hit.collider.CompareTag("Door"))
{
//Here is where you would call a function on the door trigger to activate the text.
// Or better would be to just have that code be on the player.
// That way you can avoid unnecessary calls to another gameObject just for a UI element!
}
}