ARKit-如何放置物体而不将其附着在表面上？

Question

Using ARKit I can place an object on the surface by tapping on the screen. Is it possible to place an object "in the air" instead?

For example, I want to open a portal in front of me. So when I tap on the screen I want the portal to appear at this location, but I don't want it to be attached to any surface.

Probably I have to use coordinates of my finger tap and axes of my device, but for z-axis (distance between me and the portal) I want to use some predefined value, like 1 meter for example.

How can it be made in C# (for ARKit in Unity)?

Answer 1

ScreenToWorldPoint() will do what you want. This simple example places a cube 1 meter in front of the camera. Just replace the GameObject.CreatePrimitive() part and Instantiate() your "portal" prefab instead:

public class PlaceObject : MonoBehaviour {

  float objDist = 1.0f;

  void Update() {
    if (Input.touchCount == 1 && Input.GetTouch(0).phase == TouchPhase.Began ) {
      Vector3 touchPos = Input.GetTouch (0).position;
      touchPos.z = objDist;
      Vector3 objPos = Camera.main.ScreenToWorldPoint (touchPos);

      GameObject myObj = GameObject.CreatePrimitive(PrimitiveType.Cube);
      myObj.transform.position = objPos;
      myObj.transform.localScale = new Vector3(0.1f, 0.1f, 0.1f);
    }
  }
}