Vector3.Dot

# [Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html).Dot

public static float **Dot** ([Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **lhs**, [Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **rhs**);

## 描述

两个向量的点积。

点积是一个浮点值，它等于 将两个向量的大小相乘，然后乘以向量之间角度的余弦值。

对于 [normalized](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3-normalized.html) 向量，如果它们指向完全相同的方向，Dot 返回 1； 如果它们指向完全相反的方向，返回 -1；如果向量彼此垂直，则 Dot 返回 0。

```
// detects if other transform is behind this object

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public Transform other;

void Update()
    {
        if (other)
        {
            Vector3 forward = transform.TransformDirection(Vector3.forward);
            Vector3 toOther = other.position - transform.position;

if (Vector3.Dot(forward, toOther) < 0)
            {
                print("The other transform is behind me!");
            }
        }
    }
}
```