Camera.ScreenPointToRay

설명

Returns a ray going from camera through a screen point.

Resulting ray is in world space, starting on the near plane of the camera and going through position's (x,y) pixel coordinates on the screen (position.z is ignored).

Screenspace is defined in pixels. The bottom-left of the screen is (0,0); the right-top is (pixelWidth,pixelHeight).

// Draws a line in the scene view going through a point 200 pixels
// from the lower-left corner of the screen
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    Camera cam;

    void Start()
    {
        cam = GetComponent<Camera>();
    }

    void Update()
    {
        Ray ray = cam.ScreenPointToRay(new Vector3(200, 200, 0));
        Debug.DrawRay(ray.origin, ray.direction * 10, Color.yellow);
    }
}