【Unity3D游戏开发】基础知识之Tags和Layers (三二)[转]

Tags和Layers分别表示是Unity引擎里面的标签和层，他们都是用来对GameObject进行标识的属性，Tags常用于单个GameObject，Layers常用于一组的GameObject。添加Tags和Layers的操作如下：

"Edit" -> "Project Settings" -> "Tags and Layers"来打开设置面板。

tag可以理解为一类元素的标记，如hero、enemy、apple-tree等。通过设置tag，可以方便地通过GameObject.FindWithTag()来寻找对象。GameObject.FindWithTag()只返回一个对象，要想获取多个tag为某值的对象，GameObject.FindGameObjectsWithTag()。

每个GameObject的Inspector面板最上方都也有个Layer选项，就在Tag旁边，unity已经有了几个层，我们新建个层，也叫UI，点击Add Layer，可以看到从Layer0到Layer7都灰掉了，那是不能用的，从第八个起可以用，Layer和tag还有一个很大的区别就是layer最多只能有32个层。

在使用过程中，使用Culling Mask、Layer Mask的地方实际指的就是layer。下面我们来看一段使用layer来检测碰撞的代码：

 Ray ray1 = nguiCamera.camera.ScreenPointToRay(Input.mousePosition);
 RaycastHit hit1;
 LayerMask mask =  << LayerMask.NameToLayer("UI");
  if (Physics.Raycast(ray1, out hit1, , mask.value))
 {
       return;
 } 

LayerMask的NameToLayer是通过层的名称返回该层的索引，如果是8，然后1<<8换算成LayerMask值，再用LayerMask的value就可以了。注意也必须设置collider才能接收碰撞，这里才能判断到。LayerMask实际上是一个位码操作，在Unity中Layers一共有32层，这个是不能增加或者减少的:     1 << LayerMask.NameToLayer("UI") 这一句实际上表示射线查询只在UI所在这个层级查找是返回的该名字所定义的层的层索引，注意是从0开始。

下面我们来看一个玩家控制的脚本，利用 Physics2D.Linecast检测物体是否碰撞到地面。

 using UnityEngine;
 using System.Collections;

 public class PlayerControl : MonoBehaviour
 {
     [HideInInspector]
     public bool facingRight = true;            // For determining which way the player is currently facing.
     [HideInInspector]
     public bool jump = false;                // Condition for whether the player should jump.

     public float moveForce = 365f;            // Amount of force added to move the player left and right.
     public float maxSpeed = 5f;                // The fastest the player can travel in the x axis.
     public AudioClip[] jumpClips;            // Array of clips for when the player jumps.
     public float jumpForce = 1000f;            // Amount of force added when the player jumps.
     public AudioClip[] taunts;                // Array of clips for when the player taunts.
     public float tauntProbability = 50f;    // Chance of a taunt happening.
     public float tauntDelay = 1f;            // Delay for when the taunt should happen.

     private int tauntIndex;                    // The index of the taunts array indicating the most recent taunt.
     private Transform groundCheck;            // A position marking where to check if the player is grounded.
     private bool grounded = false;            // Whether or not the player is grounded.
     private Animator anim;                    // Reference to the player's animator component.

     void Awake()
     {
         // Setting up references.
         // 在子对象里面找到groundCheck
         groundCheck = transform.Find("groundCheck");
         // 获取当前的动画控制器
         anim = GetComponent<Animator>();
     }

     void Update()
     {
         // 是为能随时检测到groundCheck这个物体，添加一个名叫Ground的Layer，然后把场景中的所有代表地面的物体的Layer设为Ground
         // 这里用到了2D射线检测Physics2D.Linecast()
         // LayerMask实际上是一个位码操作，在Unity3d中Layers一共有32层，这个是不能增加或者减少的:
         // 1 << LayerMask.NameToLayer("Ground") 这一句实际上表示射线查询只在Ground所在这个层级查找 是返回的该名字所定义的层的层索引，注意是从0开始
         // 每个GameObject的Inspector面板最上方都也有个Layer选项，就在Tag旁边，unity3d已经有了几个层，我们新建个层，也叫UI，点击Add Layer，可以看到从Layer0到Layer7都灰掉了，那是不能用的，从第八个起可以用，所以在第八个建个UI的层。
         // 一般情况下我们只用前两个参数，distance表示射线距离，默认是无限远，重点是最后一个参数layerMask，专门处理layer过滤的，是个整型，怎么用呢，是靠layer的二进制位来操作的
         // LayerMask的NameToLayer是通过层的名称返回该层的索引，这里是8，然后1<<8换算成LayerMask值，再用LayerMask的value就可以了。
         // 注意也必须设置collider才能接收碰撞，这里才能判断到。
         grounded = Physics2D.Linecast(transform.position, groundCheck.position,  << LayerMask.NameToLayer("Ground"));  

         // If the jump button is pressed and the player is grounded then the player should jump.
         // 如果点击了跳的按键，并且已经着陆，那么就可以跳起来
         if(Input.GetButtonDown("Jump") && grounded)
             jump = true;
     }

     // 因为主角游戏对象要使用到刚体力，所以一定要写在FixedUpdate里面，不能放在Update上
     void FixedUpdate ()
     {
         // Cache the horizontal input.
         // 换取水平方向的移动距离
         float h = Input.GetAxis("Horizontal");

         // The Speed animator parameter is set to the absolute value of the horizontal input.
         // 设置动画的速度变量
         anim.SetFloat("Speed", Mathf.Abs(h));

         // 给物体添加一个水平的力，让它移动的时候会产生惯性的效果
         // If the player is changing direction (h has a different sign to velocity.x) or hasn't reached maxSpeed yet...
         // 如果速度小于最大的速度
         if(h * rigidbody2D.velocity.x < maxSpeed)
             // ... add a force to the player.
             rigidbody2D.AddForce(Vector2.right * h * moveForce);

         // If the player's horizontal velocity is greater than the maxSpeed...
         if(Mathf.Abs(rigidbody2D.velocity.x) > maxSpeed)
             // ... set the player's velocity to the maxSpeed in the x axis.
             rigidbody2D.velocity = new Vector2(Mathf.Sign(rigidbody2D.velocity.x) * maxSpeed, rigidbody2D.velocity.y);

         // 转身
         // If the input is moving the player right and the player is facing left...
         if(h >  && !facingRight)
             // ... flip the player.
             Flip();
         // Otherwise if the input is moving the player left and the player is facing right...
         else if(h <  && facingRight)
             // ... flip the player.
             Flip();

         // If the player should jump...
         if(jump)
         {
             // Set the Jump animator trigger parameter.
             // 触发跳的动画
             anim.SetTrigger("Jump");

             // Play a random jump audio clip.
             int i = Random.Range(, jumpClips.Length);
             AudioSource.PlayClipAtPoint(jumpClips[i], transform.position);

             // Add a vertical force to the player.
             // 添加一个垂直的力
             rigidbody2D.AddForce(new Vector2(0f, jumpForce));

             // Make sure the player can't jump again until the jump conditions from Update are satisfied.
             jump = false;
         }
     }

     // 转身
     void Flip ()
     {
         // Switch the way the player is labelled as facing.
         facingRight = !facingRight;

         // Multiply the player's x local scale by -1.
         Vector3 theScale = transform.localScale;
         theScale.x *= -;
         transform.localScale = theScale;
     }

     public IEnumerator Taunt()
     {
         // Check the random chance of taunting.
         float tauntChance = Random.Range(0f, 100f);
         if(tauntChance > tauntProbability)
         {
             // Wait for tauntDelay number of seconds.
             yield return new WaitForSeconds(tauntDelay);

             // If there is no clip currently playing.
             if(!audio.isPlaying)
             {
                 // Choose a random, but different taunt.
                 tauntIndex = TauntRandom();

                 // Play the new taunt.
                 audio.clip = taunts[tauntIndex];
                 audio.Play();
             }
         }
     }

     int TauntRandom()
     {
         // Choose a random index of the taunts array.
         int i = Random.Range(, taunts.Length);

         // If it's the same as the previous taunt...
         if(i == tauntIndex)
             // ... try another random taunt.
             return TauntRandom();
         else
             // Otherwise return this index.
             return i;
     }
 }

原文链接：http://www.cnblogs.com/linzheng/p/3991375.html