Unity | Tag、Layer常量类生成工具

        在项目开发中我们可以对诸如Layer、Tag等编辑器数据进行常量生成，来代替在代码中通过输入字符串生成常量的形式以提高开发效率。

        Layer的生成可以通过LayerMask.LayerToName获取层名称（也可以从TagManager.asset中获得 ），Tag的生成可以手动将预制Tag标签写入常量列表，其他的自定义Tag可以从TagManager.asset中获得。

一、基本知识

1.unity预制Tag标签

        TagManager.asset文件如下方所示。unity预制的Tag标签（如Respawn、Finish、EditorOnly等6个Tag）并没有在TagManager.asset文件中。

%YAML 1.1
%TAG !u! tag:unity3d.com,2011:
--- !u!78 &1
TagManager:
  serializedVersion: 2
  tags:
  - Test
  layers:
  - Default
  - TransparentFX
  - Ignore Raycast
  - 
  - Water
  - UI
  - TestLayer
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  - 
  m_SortingLayers:
  - name: Default
    uniqueID: 0
    locked: 0

2.Layer层

        在Unity中，Layer机制是固定的，最多只能有32个Layer。这是由Unity的底层设计决定的，因为Layer是用一个32位的整型来表示的，每一位表示一个Layer。

二、工具

using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
using UnityEngine;

public class LayerManager : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        var sb = new StringBuilder();                         //准备模板生成
        sb.AppendLine("public class _Const");
        sb.AppendLine("{");

        for (int i = 0; i < 32; i++)                         //遍历所有Layer
        {
            var name = LayerMask.LayerToName(i);     //通过Unity的接口拿到Layer名称
            name = name
                .Replace(" ", "_")
                .Replace("&", "_")
                .Replace("/", "_")
                .Replace(".", "_")
                .Replace(",", "_")
                .Replace(";", "_")
                .Replace("%", "_")
                .Replace("-", "_");                              //对常见的特殊字符进行过滤
            Debug.Log(name);
            if (!string.IsNullOrEmpty(name))
                sb.AppendFormat("\tpublic const int LAYER_{0} = {1};\n", name.ToUpper(), i);
        }
        sb.AppendLine("\tpublic const string " + ("Tag_Untagged".ToUpper() + " = " + "\"Untagged\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_Respawn".ToUpper() + " = " + "\"Respawn\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_Finish".ToUpper() + " = " + "\"Finish\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_EditorOnly".ToUpper() + " = " + "\"EditorOnly\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_MainCamera".ToUpper() + " = " + "\"MainCamera\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_Player".ToUpper() + " = " + "\"Player\";"));
        sb.AppendLine("\tpublic const string " + ("Tag_GameController".ToUpper() + " = " + "\"GameController\";"));                    //把一部分内置Tag先写死
        var asset = UnityEditor.AssetDatabase.LoadAllAssetsAtPath("ProjectSettings/TagManager.asset");                                        //取得自定义Tag
        if ((asset != null) && (asset.Length > 0))
        {
            Debug.Log(asset.Length);
            for (int i = 0; i < asset.Length; i++)
            {
                //创建序列化对象
                var so = new UnityEditor.SerializedObject(asset[i]);
                var tags = so.FindProperty("tags");          //读取具体字段
                for (int j = 0; j < tags.arraySize; ++j)
                {
                    var item = tags.GetArrayElementAtIndex(j).stringValue;
                    sb.AppendFormat("\tpublic const string TAG_{0} = \"{1}\";\n", item.ToUpper(), item);
                }                                                       //添加到模板

                //获取Layer的方法二
                // var layers = so.FindProperty("layers");
                // for (int j = 0; j < layers.arraySize; ++j)
                // {
                //     var item = layers.GetArrayElementAtIndex(j).stringValue;
                //     if (!string.IsNullOrEmpty(item))
                //         sb.AppendFormat("\tpublic const int LAYER_{0} = {1};\n", item.ToUpper(), j);
                // }
            }
        }
        sb.AppendLine("}");
        File.WriteAllText("Assets/GeneratedConst.cs", sb.ToString());     //写入硬盘
        UnityEditor.AssetDatabase.Refresh();               //通知Unity刷新
    }

}

三、生成的代码

public class _Const
{
	public const int LAYER_DEFAULT = 0;
	public const int LAYER_TRANSPARENTFX = 1;
	public const int LAYER_IGNORE_RAYCAST = 2;
	public const int LAYER_WATER = 4;
	public const int LAYER_UI = 5;
	public const int LAYER_TESTLAYER = 6;
	public const string TAG_UNTAGGED = "Untagged";
	public const string TAG_RESPAWN = "Respawn";
	public const string TAG_FINISH = "Finish";
	public const string TAG_EDITORONLY = "EditorOnly";
	public const string TAG_MAINCAMERA = "MainCamera";
	public const string TAG_PLAYER = "Player";
	public const string TAG_GAMECONTROLLER = "GameController";
	public const string TAG_TEST = "Test";
}