Camera.ViewportPointToRay

# [Camera](https://docs.unity3d.com/cn/2019.4/ScriptReference/Camera.html).ViewportPointToRay

public [Ray](https://docs.unity3d.com/cn/2019.4/ScriptReference/Ray.html) **ViewportPointToRay** ([Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **pos**);

public [Ray](https://docs.unity3d.com/cn/2019.4/ScriptReference/Ray.html) **ViewportPointToRay** ([Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **pos**, [Camera.MonoOrStereoscopicEye](https://docs.unity3d.com/cn/2019.4/ScriptReference/Camera.MonoOrStereoscopicEye.html) **eye**);

## 参数

| eye | 可选参数，可用于指定要使用的眼睛变换。默认值为 Mono。 |
| ----- | ------------------------------------------------------- |

## 描述

返回从摄像机通过视口点的光线。

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

视口坐标是标准化的、相对于摄像机的坐标。摄像机左下角为 (0,0)，右上角为 (1,1)。

```
// Prints the name of the object camera is directly looking at
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    Camera cam;

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

void Update()
    {
        Ray ray = cam.ViewportPointToRay(new Vector3(0.5F, 0.5F, 0));
        RaycastHit hit;
        if (Physics.Raycast(ray, out hit))
            print("I'm looking at " + hit.transform.name);
        else
            print("I'm looking at nothing!");
    }
}
```