Mac下在Unity中调用C++库

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Unity: 2021.2.10f1c1 silicon OS: macOS Monterey 12.1 Compiler: Clang 13.0.0 arm64-apple-darwin21.1.0

一个简单的Demo

新建一个c++文件unity_api.cpp:

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#if defined(__CYGWIN32__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(_WIN64) || defined(WINAPI_FAMILY)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(__MACH__) || defined(__ANDROID__) || defined(__linux__) || defined(__QNX__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#else
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#endif

extern "C" {
UNITY_CPP_INTEROP_DLL_BRIDGE float Add(const float a,
                                       const float b) {
    return a + b;
}
}

CMakeLists.txt:

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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -O3 -D__ARM_NEON__ -DENABLE_NEON -Wno-unused-result -march=armv8-a+fp+simd+crypto -DCMAKE_APPLE_SILICON_PROCESSOR=arm64")

add_library(unity_api SHARED unity_api.cpp)

编译生成libunity_api.dylib，并且放到UnityProject/Assets/Plugins/macOS文件夹下，并且在Unity中对库进行设置：

unity_inspector

编写Unity的C#脚本PluginImport.cs:

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using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class PluginImport : MonoBehaviour
{
    [DllImport("unity_api", CallingConvention = CallingConvention.Cdecl)]
    public static extern float Add(float a, float b);
    
    // Start is called before the first frame update
    void Start()
    {
        Debug.Log(Add(1, 2));
    }

}

并且将脚本PluginImport.cs挂靠到Unity的Main Camera下，并且运行，可以在Console下看到结果：

unity_simple_test_output

使用OpenCV库

修改c++文件unity_api.cpp:

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#include <opencv2/opencv.hpp>

#if defined(__CYGWIN32__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(_WIN64) || defined(WINAPI_FAMILY)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(__MACH__) || defined(__ANDROID__) || defined(__linux__) || defined(__QNX__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#else
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#endif



extern "C" {
UNITY_CPP_INTEROP_DLL_BRIDGE float Add(const float a,
                                       const float b) {
    return a + b;
}

UNITY_CPP_INTEROP_DLL_BRIDGE bool ToGray(const char *color_img_file,
                                         const char *gray_img_file) {

    cv::Mat img = cv::imread(std::string(color_img_file));
    if (img.empty()) {
        return false;
    }

    cv::Mat img_gray;
    cv::cvtColor(img, img_gray, cv::COLOR_BGR2GRAY);
    cv::imwrite(std::string(gray_img_file), img_gray);
    return true;
}
}

CMakeLists.txt:

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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -O3 -D__ARM_NEON__ -DENABLE_NEON -Wno-unused-result -march=armv8-a+fp+simd+crypto -DCMAKE_APPLE_SILICON_PROCESSOR=arm64")

find_package(OpenCV REQUIRED)

include_directories(${OpenCV_INCLUDE_DIRS})
link_directories(${OpenCV_LIBRARY_DIRS})

add_library(unity_api SHARED unity_api.cpp)
target_link_libraries(unity_api ${OpenCV_LIBS})

编译生成libunity_api.dylib，并且放到UnityProject/Assets/Plugins/macOS文件夹下。修改Unity的C#脚本PluginImport.cs:

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using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class PluginImport : MonoBehaviour
{
    [DllImport("unity_api", CallingConvention = CallingConvention.Cdecl)]
    public static extern float Add(float a, float b);
    
    [DllImport("unity_api", CallingConvention = CallingConvention.Cdecl)]
    public static extern bool ToGray(string color_img_file, string gray_img_file);
    
    // Start is called before the first frame update
    void Start()
    {
        Debug.Log(ToGray("/Users/luohanjie/Downloads/lenna_color.png", "/Users/luohanjie/Downloads/lenna_gray.png"));
    }

}

并且将脚本PluginImport.cs挂靠到Unity的Main Camera下，并且运行，可以得到的灰度图lenna_gray.png：

lenna_gray

通过Unity调用网络摄像头

在Unity的Main Camera下添加一个Raw Image，命名为Background并且设置Tag为background。 Canvas节点中中将Render Mode设置为Screen Space - Camera，并且将Main Camera节点拖拽到Render Camera上。

background1

在Background节点(Raw Image)中，将Left，Top，Pos Z，Right，Bottom都设置为0。为了使得显示的图片比例正确，添加Aspect Ratio Fitter并且Aspect Mode设置为Fit In Parent：

background2

Main Camera下添加脚本WebCamera.cs：

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


public class WebCamera : MonoBehaviour
{
    public string cam_name = "FaceTime HD Camera";
    public int cam_width = 1280;
    public int cam_heidht = 720;
    public int cam_fps = 30;
    public AspectRatioFitter aspect_fitter;
    private WebCamTexture web_cam_tex = null;
    private bool is_init = false;
    
    // Start is called before the first frame update
    void Start()
    {
        WebCamDevice[] devices = WebCamTexture.devices;
        for (int i = 0; i < devices.Length; i++) 
        {
            if (devices[i].name == cam_name)
            {
                is_init = true;
                Debug.Log("Connect camera to " + cam_name);
                break;
            }
        }
        
        if (is_init == false) {
            Debug.Log("Can not find " + cam_name);
            return;
        }
        
        web_cam_tex = new WebCamTexture(cam_name, cam_width, cam_heidht, cam_fps);
        
        if (web_cam_tex == null) {
            is_init = false;
            Debug.Log ("Can not new WebCamTexture");
            return;
        }
        
        GameObject.FindWithTag("background").GetComponent<RawImage>().texture = web_cam_tex;
        
        web_cam_tex.Play();          
    }
    
    void OnStart (Texture preview) {
        aspect_fitter.aspectRatio = preview.width / (float)preview.height;
    }

    // Update is called once per frame
    void Update()
    {
        
    }
}

然后将Background节点拖拽到Main Camera节点中，Web Camera (Script)项目下的Aspect_fitter项目上：

background1

点击运行可以看到结果：

webcam_unity

将c++ OpenCV的Mat传输到Unity并且显示

c++文件unity_api.cpp:

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#if defined(__CYGWIN32__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(_WIN64) || defined(WINAPI_FAMILY)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(__MACH__) || defined(__ANDROID__) || defined(__linux__) || defined(__QNX__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#else
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#endif

#include <opencv2/opencv.hpp>

cv::Mat img_;

extern "C" {
UNITY_CPP_INTEROP_DLL_BRIDGE bool ReadImage(const char *color_img_file,
                                            unsigned char*& rgb24_pixels,
                                            int& width,
                                            int& height,
                                            int& size) {

    img_ = cv::imread(std::string(color_img_file));
    if (img_.empty()) {
        return false;
    }
    
    // Unity中图片坐标系原点在图片的坐下角，与OpenCV中的定义不一样。
    // 为了显示正确，需要flip操作。
    cv::flip(img_, img_, 0);
    cv::cvtColor(img_, img_, cv::COLOR_BGR2RGB);

    rgb24_pixels = img_.data;
    width = img_.cols;
    height = img_.cols;
	size = img_.cols * img_.rows * img_.channels();
    return true;
}
}

Unity的C#脚本PluginImport.cs:

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

public class PluginImport : MonoBehaviour
{    
    [DllImport("unity_api", CallingConvention = CallingConvention.Cdecl)]
    public static extern bool ReadImage(string color_img_file, ref IntPtr data, ref int width, ref int height, ref int size);
    
    // Start is called before the first frame update
    void Start()
    {        
        IntPtr data = IntPtr.Zero;
        int width = 0;
        int height = 0;
        int size = 0;
        
        bool flag = ReadImage("/Users/luohanjie/Downloads/lenna_color.png", ref data, ref width, ref height, ref size);
        
        if (!flag || size <= 0) return;
        
        byte[] buffer = new byte[size];
        
        Texture2D tex = new Texture2D(width, height, TextureFormat.RGB24, false, false); 
        
        System.Runtime.InteropServices.Marshal.Copy(data, buffer, 0, size);
		tex.LoadRawTextureData(buffer);
		tex.Apply(); 
		
		RawImage background = GameObject.FindWithTag("background").GetComponent<RawImage>(); 
		background.texture = tex;  
    }
}

在Unity的Main Camera下添加一个Raw Image，命名为Background并且设置Tag为background。

将脚本PluginImport.cs挂靠到Unity的Main Camera下，并且运行：

mat2unity

从c++读取Unity物体的Pose

c++文件unity_api.cpp:

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#if defined(__CYGWIN32__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(_WIN64) || defined(WINAPI_FAMILY)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE __declspec(dllexport) __stdcall
#elif defined(__MACH__) || defined(__ANDROID__) || defined(__linux__) || defined(__QNX__)
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#else
    #define UNITY_CPP_INTEROP_DLL_BRIDGE
#endif

extern "C" {
UNITY_CPP_INTEROP_DLL_BRIDGE void GetPose(float *pose_out) {
    // 假定我们有一个右手系的pose = [x, y, z, qw, qx, qy, qz]，表示物体在摄像头坐标系下（opencv定义）的位姿。
    std::array<float, 7> pose;
    
    // 从OpenCV的右手系转到Unity中使用的左手系
    pose[1] = -pose[1]; //y
    pose[4] = -pose[4]; //qx
    pose[6] = -pose[6]; //qz
    
    memcpy(pose_out, pose.data(), 7 * sizeof(float));
}
}

Unity的C#脚本PluginImport.cs:

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

public class PluginImport : MonoBehaviour
{    
    [DllImport("unity_api", CallingConvention = CallingConvention.Cdecl)]
    public static extern void GetPose([MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0)] float[] pose);
    
    // Start is called before the first frame update
    void Start()
    {                
        float[] obj_pose = new float[7]; // x, y, z, qw, qx, qy, qz
        GetPose(obj_pose);
        
        //方法1，根据读取的Pose设置Unity中物体的姿态
        GameObject obj = GameObject.FindWithTag("obj_tag_name");
        obj.transform.position = new Vector3((float)obj_pose[0], (float)obj_pose[1], (float)obj_pose[2]);
        obj.transform.rotation = new Quaternion((float)obj_pose[4], (float)obj_pose[5], (float)obj_pose[6], (float)obj_pose[3]);
        
        //方法2，根据读取的Pose设置Unity中摄像头的姿态
        Camera cam_obj = GameObject.FindWithTag("MainCamera").GetComponent<Camera>();
        cam_obj.transform.position = new Vector3((float)obj_pose[0], (float)obj_pose[1], (float)obj_pose[2]);
        cam_obj.transform.rotation = new Quaternion((float)obj_pose[4], (float)obj_pose[5], (float)obj_pose[6], (float)obj_pose[3]);
    }
}