OpenGL使用OpenCV处理图像进行纹理映射的使用范例

摘自：http://www.opencv.org.cn/forum/viewtopic.php?t=9045

一般来说，有2种可能性混合使用OpenGL和OpenCV。比如
1.OpenCV显示最后结果
（2D显示）：利用OpenGL作为3D计算引擎，例如计算3D曲面曲线等3D坐标数据，然后再利用OpenCV的函数投影这些坐标并画到2D图像上（OpenCV窗口）。
2.OpenGL显示最后结果（3D显示）：
利用OpenCV作为图像处理引擎， 比如图像，视频处理等，然后再利用OpenGL的图像相关函数，比如纹理映射，画到3D空间（OpenGL窗口）里边。

下边的范例属于第二种，利用OpenCV对图像进行二值化，然后再用OpenGL进行一个纹理映射。

Using OpenCV processed Image as the image of
texture mapping by OpenGL

（开发环境：VS2008+OpenCV1.1+OpenGL1.0, 如使用源码，请注意图像路径和图像大小）

#include
"stdafx.h"
#include <iostream>

#include <GL/glut.h> 

#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

using namespace std;

/*  Create texture  */
#define texImageWidth 512
#define texImageHeight 512
static GLubyte texImage[texImageHeight][texImageWidth][4];

static GLuint texName;

/*
   // coded by Huang,Haiqiao on 2010-01-05
   // Using the processed image by OpenCV as the Texture mapping image by OpenGL;
*/

void makeTexImageCV(void)
{//creating a texture image by OpenCV functions
   char* filename="D:\\OpenCV_stuff\\SampleImages\\cameraman.jpg"; 
   IplImage* imgGrey = cvLoadImage(filename,0); 
   if (imgGrey==NULL){
      cout << "No valid image input."<<endl; 
      char c=getchar();
   } 
   int imageWidth=imgGrey->width;
   int imageHeight=imgGrey->height;
   IplImage* binaryImg = cvCreateImage(cvSize(imageWidth, imageHeight),IPL_DEPTH_8U, 1);
   cvThreshold(imgGrey,binaryImg,40,255,CV_THRESH_BINARY); 
   CvScalar s;
   ////convert OpenCV image to GLubyte image
   for (int h=0;h<imageHeight;h++){ 
      for (int w=0;w<imageWidth;w++){
         s=cvGet2D(binaryImg,h,w);
         //binary image only val[0] got value.
         //otherwise val[2] is Red,val[1] is green,val[0] is blue;  
         texImage[imageHeight-h][w][0] = (GLubyte)s.val[0];
         texImage[imageHeight-h][w][1] = (GLubyte)s.val[0];
         texImage[imageHeight-h][w][2] = (GLubyte)s.val[0];
         texImage[imageHeight-h][w][3] = (GLubyte)255;//alpha
      }
   } 
   
}

void init(void)
{    
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);

   makeTexImageCV();//create texture image by OpenCV functions;

   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

   glGenTextures(1, &texName);
   glBindTexture(GL_TEXTURE_2D, texName);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, 
                   GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
                   GL_NEAREST);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texImageWidth, 
                texImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 
                texImage);
}

void display(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glEnable(GL_TEXTURE_2D);
   glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
   glBindTexture(GL_TEXTURE_2D, texName);
   glBegin(GL_QUADS);
   glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
   glTexCoord2f(0.0, 1.0); glVertex3f(-2.0, 1.0, 0.0);
   glTexCoord2f(1.0, 1.0); glVertex3f(0.0, 1.0, 0.0);
   glTexCoord2f(1.0, 0.0); glVertex3f(0.0, -1.0, 0.0);

   glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0);
   glTexCoord2f(0.0, 1.0); glVertex3f(1.0, 1.0, 0.0);
   glTexCoord2f(1.0, 1.0); glVertex3f(2.41421, 1.0, -1.41421);
   glTexCoord2f(1.0, 0.0); glVertex3f(2.41421, -1.0, -1.41421);
   glEnd();
   glFlush();
   glDisable(GL_TEXTURE_2D);
}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 1.0, 30.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.0, 0.0, -3.6);
}

void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 27://escape
         exit(0);
         break;
      default:
         break;
   }
}

int main(int argc, char *argv[]) 
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(550, 550);
   glutInitWindowPosition(100, 100);
   glutCreateWindow("OpenCV image Texture Mapping OpenGL");
   init();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc(keyboard);
   glutMainLoop();
   return 0; 
}