Unity使用C++作為遊戲邏輯腳本的研究

05-11

文章申明：本文來自JacksonDunstan的博客系列文章內容摘取和翻譯，版權歸其所有，附上原文的鏈接，大家可以有空閱讀原文：C++ Scripting( in Unity)

一、C#和C++的通信

前面我的文章寫過c#/c/lua是如何交互的，通過將c#的函數和屬性，註冊到lua虛擬機中，可以實現通過c來互相交互。

而c#和c++的交互，也是非常類似的，c#可以直接的通過P/Invoke的方式來調用c++的函數，而C++調用C#的函數，C++的函數是被封裝成DLL來放在Unity的工程文件中的Plugins中，則需要基於.NET來操作，利用Marshal.GetFunctionPointerForDelegate來獲取函數的指針，然後傳遞到c++中進行操作。

二、編輯器下實現實時的編譯和腳本更新

在Unity中，我們可以在打開的Unity中，直接編譯c#的文件，這樣不需要每次都關閉工程再打開來執行編譯，而C++由於通過DLL來調用，每次更新的C++都需要關閉工程，然後更新DLL，然後打開工程，這樣的操作，對於編輯器下的開發是極其耗費的。

對於上面提到的反覆開關工程執行DLL的更新，可以利用[DllImport]的屬性來實現在編輯器下的更新：

該屬性是基於OS的，所以不會存在跨平台的問題。

三、示例代碼展示

show the code

c# code part:

using System;using System.IO;using System.Runtime.InteropServices;using UnityEngine;class TestScript:MonoBehaviour{#if UNITY_EDITOR // pointer handle to the C++ DLL public IntPtr libarayHandle; public delegate void InitDelegate(IntPtr gameObjectNew, IntPtr gameObjectGetTransform, IntPtr transformSetPosition);#endif}#if UNITY_EDITOR_OSX || UNITY_EDITOR_LINUX //OSX 和Linux下的導入 [DLLImport("__Internal")] public static extern IntPtr dlopen(string path, int flag); [DllImport("__Internal")] public static extern IntPtr dlsym(IntPtr handle, string symbolName); [DllImport("__Internal")] public static extern int dlclose(IntPtr handle); public static IntPtr OpenLibrary(string path) { IntPtr handle = dlopen(path, 0); if(handle == IntPtr.Zero) { throw new Exception("Couldnt open native library: "+ path); } return handle; } public static void CloseLibrary(IntPtr libraryHandle) { dlclose(libraryHandle); } public static T GetDelegate<T>(IntPtr libraryHandle, string functionName) where T: class { IntPtr symbol = dlsym(libraryHandle, functionName); if(symbol == IntPtr.Zero) { throw new Exception("Couldnt get function:" + functionName); } return Marshal.GetDelegateForFunctionPointer(symbol, typeof(T)) as T; }#elif UNITY_EDITOR_WIN // win 編輯器下 [DllImport("kernel32")] public static extern IntPtr LoadLibrary(string path); [DllImport("kernel32")] public static extern IntPtr GetProcAddress(IntPtr libraryHandle, string symbolName); [DllImport("kernel32)] public static extern bool FreeLibrary(IntPtr libraryHandle); public static IntPtr OpenLibrary(string path) { IntPtr handle = LoadLibrary(path); if(handle == IntPtr.Zero) { throw new Exception("Couldnt open native library: "+ path); } return handle; } public static void CloseLibrary(IntPtr libraryHandle) { FreeLibrary(libraryHandle); } public static T GetDelegate<T>(IntPtr libraryHandle, string functionName) where T: class { IntPtr symbol = GetProcAddress(libraryHandle, functionName); if(symbol == IntPtr.Zero) { throw new Exception("Couldnt get function:" + functionName); } return Marshal.GetDelegateForFunctionPointer(symbol, typeof(T)) as T; }#else //本地載入 [DllImport("NativeScript")] static extern void Init(IntPtr gameObjectNew, IntPtr gameObjectGetTransform, IntPtr transformSetPosition); [DllImport("NativeScript")] static extern void MonoBehaviourUpdate();#endif delegate int GameObjectNewDelegate(); delegate int GameObjectGetTransformDelegate(int thisHandle); delegate void TransformSetPositionDelegate(int thisHandle, Vector3 position);#if UNITY_EDITOR_OSX const string LIB_PATH = "/NativeScript.bundle/Contents/MacOS/NativeScript";#elif UNITY_EDITOR_LINUX const string LIB_PATH = "/NativeScript.so";#elif UNITY_EDITOR_WIN const string LIB_PATH = "/NativeScript.dll";#endif void Awake() {#if UNITY_EDITOR //open the native library libraryHandle = OpenLibrary(Application.dataPath + LIB_PATH); InitDelegate Init = GetDelegate<InitDelegate>(libraryHandle, "Init"); MonoBehaviourUpdate = GetDelegate<MonoBehaviourUpdateDelegate>( libraryHandle,"MonoBehaviourUpdate");#endif //init the C++ Library ObjectStore.Init(1024); Init( Marshal.GetFunctionPointerForDelegate(new GameObjectNewDelegate(GameObjectNew)), Marshal.GetFunctionPointerForDelegate(new GameObjectGetTransformDelegate(GameObjectGetTransform)), Marshal.GetFunctionPointerForDelegate(new TransformSetPositionDelegate(TransformSetPosition)) ); } void Update() { MonoBehaviourUpdate(); } void OnApplicationQuit() {#if UNITY_EDITOR CloseLibrary(libraryHandle); libraryHandle = IntPtr.Zero;#endif } //c# function for c++ call static int GameObjectNew() { GameObject go = new GameObject(); return ObjectStore.Store(go); } static int GameObjectGetTransform(int thisHandle) { GameObject go = (GameObject)ObjectStore.Get(thisHandle); Transform transform = go.transform; return ObjectStore.Store(transform); } static void TransformSetPosition(int handle, Vector3 position) { Transform t =(Transform)ObjectStore.Get(handle); t.position = position; }}

c++ code part:

#ifdef _WIN32 #define DLLEXPORT __declspec(dllexport)#else #define DLLEXPORT#endifextern "C"{ //C# VECTOR STRUCT struct Vector3 { float x; float y; float z; } //c# function for c++ to call int(*GameObjectNew)(); int(*GameObjectGetTransform)(int thisHandle); void(*TransformSetPosition)(int thisHandle, Vector3 position); //c++ functions for c# to call int numCreated; DLLExport void Init( int(*gameObjectNew)(), int(*gameObjectGetTrasform)(int), void(*transformSetPosition)(int, Vector3)){ GameObjectNew = gameObjectNew; GameObjectGetTransform = gameObjectGetTransform; TransformSetPosition = trasformSetPosition; numCreated = 0;} // DLLEXPORT void MonoBehaviourUpdate(int thisHandle) { if( numCreated < 10) { //獲取函數handle,然後操作 int goHandle = GameObjectNew(); int transformHandle = GameObejctGetTransform(goHandle); float comp = 10.0f * (float)numCreated; Vector3 position = {comp, comp, comp}; TransformSetPosition(transformHandle, position); numCreated++; } }}

四、總結

C#和C++的相互交互，是基於.NET和P/Invoke，那麼我們可以同理退出c#和lua的操作，其實質就是對handle進行包裝，然後進行相關的操作，這個在後續的文章中在研究，先寫到這兒，祝大家五一快樂，我也回家過節去了，哈哈~