The most common use of a Ray from the camera is to perform a raycast out into the scene. A raycast sends an imaginary “laser beam” along the ray from its origin until it hits a collider in the scene. Information is then returned about the object and the point that was hit in a RaycastHit object. This is a very useful way to locate an object based on its onscreen image. For example, the object at the mouse position can be determined with the following code:
using UnityEngine;
using System.Collections;
public class ExampleScript : MonoBehaviour {
public Camera camera;
void Start(){
RaycastHit hit;
Ray ray = camera.ScreenPointToRay(Input.mousePosition);
if (Physics.Raycast(ray, out hit)) {
Transform objectHit = hit.transform;
// Do something with the object that was hit by the raycast.
}
}
}