Camera.ScreenPointToRay

描述

返回从摄像机通过屏幕点的光线。

产生的光线位于世界空间中，从摄像机的近平面开始，并通过屏幕上 位置的 (x,y) 像素坐标（忽略 position.z）。

屏幕空间以像素定义。屏幕的左下角为 (0,0)，右上角为 (pixelWidth -1,pixelHeight -1)。

//Attach this script to your Camera
//This draws a line in the scene view going through a point 200 pixels from the lower-left corner of the screen
//To see this, enter Play Mode and switch to the Scene tab. Zoom into your Camera's position.
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);
    }
}