Vector3.MoveTowards

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

public static [Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **MoveTowards** ([Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **current**, [Vector3](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.html) **target**, float **maxDistanceDelta**);

## 参数

| current          | 移动的开始位置。                    |
| ------------------ | ------------------------------------- |
| target           | 移动的目标位置。                    |
| maxDistanceDelta | 每次调用移动 `current` 的距离。 |

## 返回

**Vector3** 新位置。

## 描述

计算 `current` 指定的点与 `target` 指定的点之间的位置，移动距离不超过 `maxDistanceDelta` 指定的距离。

使用 [MoveTowards](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3.MoveTowards.html) 成员将 `current` 位置处的对象移向 `target` 位置。通过使用此函数计算的位置来更新每个帧的对象位置，您可以平滑地将其移向目标。使用 `maxDistanceDelta` 参数来控制移动的速度。如果 `current` 位置相比 [maxDistanceDelta](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3-maxDistanceDelta.html) 更靠近 `maxDistanceDelta`，则返回值等于 `maxDistanceDelta`；新位置不会过冲 `maxDistanceDelta`。要确保对象速度与帧率无关，请将 `maxDistanceDelta` 值乘以 [Time.deltaTime](https://docs.unity3d.com/cn/2019.4/ScriptReference/Time-deltaTime.html)（或者 FixedUpdate 循环中的 [Time.fixedDeltaTime](https://docs.unity3d.com/cn/2019.4/ScriptReference/Time-fixedDeltaTime.html)）。

请注意，如果将 [maxDistanceDelta](https://docs.unity3d.com/cn/2019.4/ScriptReference/Vector3-maxDistanceDelta.html) 设置为负值，则该函数将返回与 `target` 相反方向的位置。

```
using UnityEngine;
using System.Collections;

// Vector3.MoveTowards example.

// A cube can be moved around the world. It is kept inside a 1 unit by 1 unit
// xz space. A small, long cylinder is created and positioned away from the center of
// the 1x1 unit. The cylinder is moved between two locations. Each time the cylinder is
// positioned the cube moves towards it. When the cube reaches the cylinder the cylinder
// is re-positioned to the other location. The cube then changes direction and moves
// towards the cylinder again.
//
// A floor object is created for you.
//
// To view this example, create a new 3d Project and create a Cube placed at
// the origin. Create Example.cs and change the script code to that shown below.
// Save the script and add to the Cube.
//
// Now run the example.

public class Example : MonoBehaviour
{
    // Adjust the speed for the application.
    public float speed = 1.0f;

// The target (cylinder) position.
    private Transform target;

void Awake()
    {
        // Position the cube at the origin.
        transform.position = new Vector3(0.0f, 0.0f, 0.0f);

// Create and position the cylinder. Reduce the size.
        GameObject cylinder = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
        Camera.main.transform.position = new Vector3(0.85f, 1.0f, -3.0f);

// Grab cylinder values and place on the target.
        target = cylinder.transform;
        target.transform.localScale = new Vector3(0.15f, 1.0f, 0.15f);
        target.transform.position = new Vector3(0.8f, 0.0f, 0.8f);

// Position the camera.
        Camera.main.transform.position = new Vector3(0.85f, 1.0f, -3.0f);
        Camera.main.transform.localEulerAngles = new Vector3(15.0f, -20.0f, -0.5f);

// Create and position the floor.
        GameObject floor = GameObject.CreatePrimitive(PrimitiveType.Plane);
        floor.transform.position = new Vector3(0.0f, -1.0f, 0.0f);
    }

void Update()
    {
        // Move our position a step closer to the target.
        float step =  speed * Time.deltaTime; // calculate distance to move
        transform.position = Vector3.MoveTowards(transform.position, target.position, step);

// Check if the position of the cube and sphere are approximately equal.
        if (Vector3.Distance(transform.position, target.position) < 0.001f)
        {
            // Swap the position of the cylinder.
            target.position *= -1.0f;
        }
    }
}
```