Camera.ScreenPointToRay

Description

Возвращает луч, идущий от камеры через точку на экране.

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).

Размеры экрана определяется в пикселях. Левая нижняя часть экрана имеет координаты (0,0); правая верхняя (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);
    }
}