文章申明:本文来自JacksonDunstan的博客系列文章内容摘取和翻译,版权归其所有,附上原文的链接,大家可以有空阅读原文:C++ Scripting( in Unity)
一、C#和C++的通信
前面我的文章写过c#/c/lua是如何交互的,通过将c#的函数和属性,注册到lua虚拟机中,可以实现通过c来互相交互。
而c#和c++的交互,也是非常类似的,c#可以直接的通过P/Invoke的方式来调用c++的函数,而C++调用C#的函数,C++的函数是被封装成DLL来放在Unity的工程文件中的Plugins中,则需要基于.NET来操作,利用Marshal.GetFunctionPointerForDelegate来获取函数的指针,然后传递到c++中进行操作。
二、编辑器下实现实时的编译和脚本更新
在Unity中,我们可以在打开的Unity中,直接编译c#的文件,这样不需要每次都关闭工程再打开来执行编译,而C++由于通过DLL来调用,每次更新的C++都需要关闭工程,然后更新DLL,然后打开工程,这样的操作,对于编辑器下的开发是极其耗费的。
对于上面提到的反复开关工程执行DLL的更新,可以利用[DllImport]的属性来实现在编辑器下的更新:
该属性是基于OS的,所以不会存在跨平台的问题。
三、示例代码展示
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下的导入 [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("Couldn't 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("Couldn't get function:" + functionName); } return Marshal.GetDelegateForFunctionPointer(symbol, typeof(T)) as T; } #elif UNITY_EDITOR_WIN // win 编辑器下 [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("Couldn't 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("Couldn't get function:" + functionName); } return Marshal.GetDelegateForFunctionPointer(symbol, typeof(T)) as T; } #else //本地加载 [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 #endif extern "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) { //获取函数handle,然后操作 int goHandle = GameObjectNew(); int transformHandle = GameObejctGetTransform(goHandle); float comp = 10.0f * (float)numCreated; Vector3 position = {comp, comp, comp}; TransformSetPosition(transformHandle, position); numCreated++; } } }
四、总结
C#和C++的相互交互,是基于.NET和P/Invoke,那么我们可以同理退出c#和lua的操作,其实质就是对handle进行包装,然后进行相关的操作,这个在后续的文章中在研究,先写到这儿,祝大家五一快乐,我也回家过节去了,哈哈~