Question Make a GameObject appear when AR Camera gets at a specific distance from it

Hi!

I am utilizing ARFoundation in Unity and being trying to make an object appear, at a specific camera distance or less, from it. What is the best practice/approach to achieve this, taking into consideration possible offset(s) that need to be applied for better fine tuning during ray-casting process (to increase accuracy)?

This is the code I've written, the script is attached to an empty GameObject with a Collider, thus with a successful hit at the predefined distance value (or less), the required GameObject appears...


Transform hitTransform;

void Update()
{
Ray ray = Camera.main.ViewportPointToRay(gameObject.transform.position);
RaycastHit hit;

if (Physics.Raycast(ray, out hit))
{
hitTransform = hit.transform;
POI_DistancefromCamera = Vector3.Distance(Camera.main.transform.position, gameObject.transform.position);

if (POI_DistancefromCamera <= 1)
RayCastHitTrigger = true;
}

if (RayCastHitTrigger)
{
RequiredGameObject.SetActive(true);
}


Thank you!

 

Code (CSharp):

1. Ray ray = Camera.main.ViewportPointToRay(gameObject.transform.position);

This would be your first issue. The position of the GameObject is not a position in the Viewport (ScreenSpace) but a position in the Scene (WorldSpace).

If your goal is to enable the GameObject if the camera is within a certain distance, and looking in its direction, the easiest way would be to skip raycasting altogether.

The distance can be retrieved as you are doing above (Vector3.Distance(A, B)).
The 'Look-Direction' can be calculated by comparing the direction to the GameObject (GameObject.position - Camera.position) with the Forward-Direction of the Camera (Camera.main.transform.forward). Both of these will be in World-Space (they are both directions though, so both have the Camera-position at (0,0,0)).

Vector3.Angle(CameraForward, GameObjectDirection) will give you the (unsigned) angle between the two directions.

 

Thank you! But skipping Raycasting is not what I had in mind, what would then be the actual code, needed to be implemented in the UPDATE function?

 

From: https://docs.unity3d.com/ScriptReference/Camera.ViewportToWorldPoint.html
Viewport space is normalized and relative to the camera. The bottom-left of the viewport is (0,0); the top-right is (1,1).
So the center of the screen is (0.5, 0.5)