Unity调用C++ dll的那些坑

目录

一、项目背景

二、C++SDK的封装

1.第一版SDK

2.第二版SDK

（1）修改SDKCaller.h

（2）AvatarDriver.h

（3）AvatarDriver.cpp

三、Unity调用DLL

---

一、项目背景

        最近在做一款虚拟人驱动项目，算法数据是以C++ SDK的形式封装起来的，那么这就涉及到了unity调用C++ dll。

二、C++SDK的封装

        这个项目之前本人是有C++ SDK封装经验的，所以一些细节以及遵循的原则就不记录了。

1.第一版SDK

        在和算法老师联调的过程中，封装的第一版dll的头文件SDKCaller.h是这样的：

#pragma once
#include 
#ifdef WIN32
#ifdef DLL_EXPORTS
#define EXPORT_CLASS __declspec(dllexport)
#define EXPORT_API extern "C" __declspec(dllexport)
#define EXPORT_CLASS_API
#else
#define EXPORT_CLASS __declspec(dllimport)
#define EXPORT_API extern "C" __declspec(dllimport)
#define EXPORT_CLASS_API
#endif
#else
#define EXPORT_CLASS
#define EXPORT_API extern "C" __attribute__((visibility("default")))
#define EXPORT_CLASS_API __attribute__((visibility("default")))
#endif

class EXPORT_CLASS SDKCaller
{
public:
    EXPORT_CLASS_API SDKCaller(const char* config_path);
public:
    // 初始化SDK
    EXPORT_CLASS_API int InitSDKBody(const char* model_path_det, const char* model_path_body);
    EXPORT_CLASS_API int InitSDKFace(const char* FaceDetect_modelpath, const char* FaceLandmarks_modelpath, const char* MouthLandmarks_modelpath, const char* FaceReconstruct_modelpath);
    EXPORT_CLASS_API int InitSDKHand(const char* det_model_path, const char* hand_mesh_model_path, int max_batch);
    EXPORT_CLASS_API int InitSDKSMPLX(const char* smplx_path);
    // 调用SDK
    EXPORT_CLASS_API int CallSDK(const unsigned char* buffer, const int height, const int width, bool start,  bool end, int userinfo, char ** outputjson, int &len);
    EXPORT_CLASS_API void Destory(char* p);

};

        根据我的经验，这个头文件及dll是没毛病的。但是给unity调用的话，这个类SDKCaller怎么映射到Unity中？第二版dll诞生~

2.第二版SDK

        在Unity中调用C++写的类，dll直接按上面的方式导出是不行的。我们需要使用函数来代替类，也就是说在上述的类的基础上再封装一层，用函数将类包装起来。直接看源码吧：

（1）修改SDKCaller.h

        SDKCaller.h这个头文件要被封装，那它就不对外提供了，所以也不需要加_declspec(dllexport)字段。

#pragma once
#include 

class  SDKCaller
{
public:
      SDKCaller(const char* config_path);
public:
      int InitSDKBody(const char* model_path_det, const char* model_path_body);

      int InitSDKFace(const char* FaceDetect_modelpath, const char* FaceLandmarks_modelpath, const char* MouthLandmarks_modelpath, const char* FaceReconstruct_modelpath);

      int InitSDKHand(const char* det_model_path, const char* hand_mesh_model_path, int max_batch);

      int InitSDKSMPLX(const char* smplx_path);
   
      int CallSDK(const unsigned char* buffer, const int height, const int width, bool start,  bool end, int userinfo, char ** outputjson, int &len);
     
      void Destory(char* p);

};

（2）AvatarDriver.h

        AvatarDriver.h对上述的SDKCaller类进行了封装，这个头文件要对外暴露，所以需要加_declspec(dllexport)字段。

#pragma once

#ifdef WIN32
#ifdef DLL_EXPORTS
#define EXPORT_CLASS __declspec(dllexport)
#define EXPORT_API extern "C" __declspec(dllexport)
#define EXPORT_CLASS_API
#else
#define EXPORT_CLASS __declspec(dllimport)
#define EXPORT_API extern "C" __declspec(dllimport)
#define EXPORT_CLASS_API
#endif
#else
#define EXPORT_CLASS
#define EXPORT_API extern "C" __attribute__((visibility("default")))
#define EXPORT_CLASS_API __attribute__((visibility("default")))
#endif
extern "C" {
	struct  SDKCaller;

	EXPORT_CLASS_API SDKCaller* GenerateAISDK(const char* config_path);

	EXPORT_CLASS_API int AIInitSDKBody(SDKCaller* sdk,const char* model_path_det, const char* model_path_body);

	EXPORT_CLASS_API int AIInitSDKFace(SDKCaller* sdk, const char* FaceDetect_modelpath, const char* FaceLandmarks_modelpath, const char* MouthLandmarks_modelpath, const char* FaceReconstruct_modelpath);

	EXPORT_CLASS_API int AIInitSDKHand(SDKCaller* sdk, const char* det_model_path, const char* hand_mesh_model_path, int max_batch);

	EXPORT_CLASS_API int AIInitSDKSMPLX(SDKCaller* sdk, const char* smplx_path);

	EXPORT_CLASS_API int AICallSDK(SDKCaller* sdk, const unsigned char* buffer, const int height, const int width, bool start, bool end, int userinfo, char** outputjson, int& len);

	EXPORT_CLASS_API void AIDestory(SDKCaller* sdk, char* p);

	EXPORT_CLASS_API void AIReleaseAISDK(SDKCaller* sdk);
}

（3）AvatarDriver.cpp

        AvatarDriver.h只是函数声明，AvatarDriver.cpp才是函数实现，函数内部是对SDKCaller类的成员函数的调用。

#include "SDKCaller.h"
#include "AvatarDriver.h"

SDKCaller* GenerateAISDK(const char* config_path)
{
	return new SDKCaller(config_path);
}

inline int AIInitSDKBody(SDKCaller* sdk, const char* model_path_det, const char* model_path_body)
{
	return sdk->InitSDKBody(model_path_det, model_path_body);
}

inline int AIInitSDKFace(SDKCaller* sdk, const char* FaceDetect_modelpath, const char* FaceLandmarks_modelpath, const char* MouthLandmarks_modelpath, const char* FaceReconstruct_modelpath)
{
	return sdk->InitSDKFace(FaceDetect_modelpath, FaceLandmarks_modelpath, MouthLandmarks_modelpath, FaceReconstruct_modelpath);
}

inline int AIInitSDKHand(SDKCaller* sdk, const char* det_model_path, const char* hand_mesh_model_path, int max_batch)
{
	return sdk->InitSDKHand(det_model_path, hand_mesh_model_path, max_batch);
}

inline int AIInitSDKSMPLX(SDKCaller* sdk, const char* smplx_path)
{
	return sdk->InitSDKSMPLX(smplx_path);
}

inline int AICallSDK(SDKCaller* sdk, const unsigned char* buffer, const int height, const int width, bool start, bool end, int userinfo, char** outputjson, int& len)
{
	return sdk->CallSDK(buffer, height, width, start, end, userinfo, outputjson, len);
}


inline void AIDestory(SDKCaller* sdk, char* p)
{
	sdk->Destory(p);
}

inline void AIReleaseAISDK(SDKCaller* sdk)
{
	delete sdk;

}

三、Unity调用DLL

        我们需要将dll（及其依赖的dll）放入到Unity项目Plugins文件夹下，这个熟悉Unity的人都知道~俺就不细说了。那C++与C#如何映射呢？我们需要用到DllImport命令引入dll（该SDK名称为Avatar_driver.dll），并将AvatarDriver.h以C#语言的方式进行声明。

C++	C#
SDKCaller* （自定义类的指针）	IntPtr
const char*	IntPtr
const unsigned char*	IntPtr
作为出参的char**	ref IntPtr
int&	ref int

using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using UnityEngine;

public class AIDLL : MonoBehaviour
{
    [DllImport("avatar_driver")]
    public static extern IntPtr GenerateAISDK(IntPtr config_path);

    [DllImport("avatar_driver")]
    public static extern int AIInitSDKBody(IntPtr sdk, IntPtr model_path_det, IntPtr model_path_body);
    [DllImport("avatar_driver")]
    public static extern int AIInitSDKFace(IntPtr sdk, IntPtr FaceDetect_modelpath, IntPtr FaceLandmarks_modelpath, IntPtr MouthLandmarks_modelpath, IntPtr FaceReconstruct_modelpath);
    [DllImport("avatar_driver")]
    public static extern int AIInitSDKHand(IntPtr sdk, IntPtr det_model_path, IntPtr hand_mesh_model_path, int max_batch);
    [DllImport("avatar_driver")]
    public static extern int AIInitSDKSMPLX(IntPtr sdk, IntPtr smplx_path);
    [DllImport("avatar_driver")]
    public static extern int AICallSDK(IntPtr sdk, IntPtr buffer, int height, int width, bool start, bool end, int userinfo, ref IntPtr outputjson, ref int len);
    [DllImport("avatar_driver")]
    public static extern void AIDestory(IntPtr sdk, IntPtr p);
    [DllImport("avatar_driver")]
    public static extern void AIReleaseAISDK(IntPtr sdk);
}

        接下来我们就能在unity中进行C++接口的调用咯~

• 字符串转IntPtr，需要用到函数Marshal.StringToHGlobalAnsi()
• IntPtr转字符串，需要用到函数Marshal.PtrToStringAnsi()

IntPtr configPath = Marshal.StringToHGlobalAnsi(Application.streamingAssetsPath + "/config_test.ini");

IntPtr sdk = AIDLL.GenerateAISDK(configPath);

System.IntPtr result = new System.IntPtr();

AIDLL.AICallSDK(GameManager.sdk, pixelPointer, webCamTexture.height, webCamTexture.width, false, false, userInfoSet, ref result, ref len);

string jsonStr = Marshal.PtrToStringAnsi(result);