Camera.ScreenPointToRay

Description

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）。

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);
    }
}