【Unity游戏开发】基于xLua构建一个简单的3D游戏框架

一、xLua简介

xLua是基于Lua语言的开源插件，能够支持在Unity中嵌入Lua脚本（Lua脚本支持热更，适用于游戏的业务逻辑开发和维护）
xLua源码地址

二、构建方法

新建一个Unity项目（模板选择Universal 3D（URP））
下载xLua源码，将Assets目录及其子目录下的全部文件拷贝到Unity项目的Assets目录下
如出现编译错误“error CS0246: The type or namespace name 'MemberInfo' could not be found (are you missing a using directive or an assembly reference?)”，则打开报错的ExampleGenConfig.cs文件，把“using System.Reflection;”的注释去掉
创建Lua脚本：在Assets/Resource/Lua目录下（没有则自行创建），创建PlayerController.lua

local PlayerController = 
{
    speed = 2
}

function PlayerController:Update()
    self.direction = CS.UnityEngine.Vector3(0, 0, 0)
    if CS.UnityEngine.Input.GetKey(CS.UnityEngine.KeyCode.W) then
        self.direction = self.direction + CS.UnityEngine.Vector3(0, 0, 1)
    end
    if CS.UnityEngine.Input.GetKey(CS.UnityEngine.KeyCode.S) then
        self.direction = self.direction + CS.UnityEngine.Vector3(0, 0, -1)
    end
    if CS.UnityEngine.Input.GetKey(CS.UnityEngine.KeyCode.A) then
        self.direction = self.direction + CS.UnityEngine.Vector3(-1, 0, 0)
    end
    if CS.UnityEngine.Input.GetKey(CS.UnityEngine.KeyCode.D) then
        self.direction = self.direction + CS.UnityEngine.Vector3(1, 0, 0)
    end
    self.gameObject.transform.position = self.gameObject.transform.position + self.direction * self.speed * CS.UnityEngine.Time.deltaTime
end

_G.PlayerController = PlayerController

创建LuaImporter：在Assets/Scripts/Editor目录下，创建LuaImporter.cs，使得Unity能够将.lua后缀的文件识别为文本文件

using System.IO;
using UnityEditor;
using UnityEditor.AssetImporters;
using UnityEngine;
using XLuaTest;

[ScriptedImporter(1, ".lua")]
public class LuaImporter : ScriptedImporter
{
    public override void OnImportAsset(AssetImportContext ctx)
    {
        var luaTxt = File.ReadAllText(ctx.assetPath);
        var assetsText = new TextAsset(luaTxt);
        ctx.AddObjectToAsset("main obj", assetsText);
        ctx.SetMainObject(assetsText);
    }
}

创建并使用Lua虚拟机：在Assets/Scripts目录下，创建LuaManager.cs脚本，作为lua脚本执行的入口

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using XLua;

public class LuaManager : MonoBehaviour
{
    LuaEnv luaEnv;
    LuaTable luaTable;
    LuaFunction luaFunction;
    void Start()
    {
        // 创建Lua虚拟机
        luaEnv = new LuaEnv();
        // 指定Lua文件的加载方式
        luaEnv.AddLoader(LoadLuaFile);
        // 将C#对象存入Lua表中
        GameObject player = GameObject.Find("Player");
        luaEnv.DoString("require('Lua.PlayerController')");
        // 设置PlayerController的gameObject属性，并获取Update函数
        luaTable = luaEnv.Global.Get<LuaTable>("PlayerController");
        luaTable.Set("gameObject", player);
        luaFunction = luaTable.Get<LuaFunction>("Update");
    }
    void Update()
    {
        // 执行PlayerController:Update()函数
        luaFunction.Call(luaTable);
    }
    public static byte[] LoadLuaFile(ref string filepath)
    {
        filepath = $"{filepath.Replace(".", "/")}";
        TextAsset file = Resources.Load(filepath) as TextAsset;
        return file.bytes;
    }
}