Unity调用dll打开相机C++、C#

（1）testdll.h中添加如下语句：

#pragma once


extern "C"   __declspec(dllexport) int calAdd(int a, int b);

extern "C"  __declspec(dllexport) double calSubtract(double a, double b);



#include<opencv2/opencv.hpp>
using namespace cv;

（2）testdll.cpp中添加如下语句： 

#include<opencv2/opencv.hpp>
using namespace cv;

//..\..\UnityActivate\VSActivateUnity.exe


#define EXPORT_API __declspec(dllexport)

VideoCapture my_camera;
Mat image, imageR, imageL;
int m_width = 640;
int m_height = 480;


extern "C" bool  EXPORT_API openCamera()
{
	bool my_open = false;
	while (!my_camera.isOpened())
	{
		//std::cout << "Cannot open the camera!" << std::endl;
		my_camera.open(0);
	}
	my_camera.set(CV_CAP_PROP_FRAME_WIDTH, m_width);
	my_camera.set(CV_CAP_PROP_FRAME_HEIGHT, m_height);
	if (my_camera.isOpened())
	{
		my_open = true;
	}
	return my_open;
}

extern "C" void   EXPORT_API recieveFrame(uchar* texturePtr)
{

	Mat my_frameBGR;
	Mat my_frameRBG;
	my_camera >> my_frameBGR;
	if (my_frameBGR.data)
	{
		cvtColor(my_frameBGR, my_frameRBG, CV_BGR2RGB);
		memcpy(texturePtr, my_frameRBG.data, my_frameRBG.cols*my_frameRBG.rows*my_frameRBG.channels()*sizeof(uchar));
	}

}

extern "C" void EXPORT_API closeCamera()
{
	if (my_camera.isOpened())
	{
		my_camera.release();
	}
}


extern "C" void EXPORT_API poem(char* poetry)
{

	int  value[2][2] = { { 1, 2 }, { 9, 10 } };
	char mypoem[] = { "book2" };
	//poetry = (char*)malloc(sizeof(mypoem));
	int n = sizeof(mypoem);
	memcpy(poetry, mypoem, 10);

}

在Unity中编写C#脚本如下，挂在GameObject上

using UnityEngine;
using System.Collections;
using System.Runtime.InteropServices;//用c++中dll文件需要引入  

public class dll : MonoBehaviour {


	[DllImport("dllUnity")]
	public static extern bool openCamera();

	[DllImport("dllUnity")]
	public static extern void recieveFrame(byte[] imageData);

	[DllImport("dllUnity")]
	public static extern void closeCamera();



	public bool IsOpen = false;
	public byte[] imageData;
	public Texture2D tex;
	public int Width = 640;
	public int Length = 480;

	// Use this for initialization
	void Start () {
			//open one camera
       IsOpen = openCamera();
        if (IsOpen)
        {
            imageData = new byte[Length * Width * 3];
            tex = new Texture2D(Width, Length, TextureFormat.RGB24, false);
        }

	}
	
	// Update is called once per frame
	void Update () {
	
		//update one camera
        if (IsOpen)
        {
			recieveFrame(imageData);
			tex.LoadRawTextureData(imageData);
			tex.Apply();
			GetComponent<Renderer>().material.mainTexture = tex;

        }
	}


	void OnGUI()
	{
		if (!IsOpen)
		{
			//string myword = "打开相机失败！";
			string myword = "camera pause for a while！";
			GUI.TextArea(new Rect(200,100,200,50),myword,new GUIStyle());
		}
		//to get the button
		GUI.color = Color.yellow;   
		GUI.backgroundColor = Color.red; 
		if(GUI.Button(new Rect(20,50,60,30), "continue"))
		{
			IsOpen = true;
		}

		GUI.color = Color.white;    
		GUI.backgroundColor = Color.green; 
		if(GUI.Button(new Rect(20,100,60,30), "pause"))
		{
			IsOpen = false;
		}

		GUI.color = Color.white;
		GUI.backgroundColor = Color.blue; 
		if(GUI.Button(new Rect(20,150,60,30), "close"))
		{
			closeCamera();
		}


	}
}

Unity设置：