sad

void load3DTexFromPVM(const char* fileName,
                        int xSize=64,
                        int ySize=64,
                        int zSize=64) {
   const int size = xSize*ySize*zSize;
   FILE *pFile = fopen(fileName,"rb");
   if(NULL == pFile) {
     cerr << "Fail to open texture file" << endl;
     exit(EXIT_FAILURE);
   }
   GLubyte* texels=new GLubyte[size];
   fread(texels,sizeof(GLubyte),size,pFile);
   fclose(pFile);

   //load data into a 3D texture
   glGenTextures(1, &texname);
   glBindTexture(GL_TEXTURE_3D, texname);

   // set the texture parameters
   glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

   glTexImage3D(GL_TEXTURE_3D,0,GL_INTENSITY,xSize,ySize,zSize,0,GL_LUMINANCE,GL_UNSIGNED_BYTE,texels);
   //glTexImage3D(GL_TEXTURE_3D,0,GL_RGB8,xSize,ySize,zSize,0,GL_RGB,GL_UNSIGNED_BYTE,texels);
   delete[] texels;
}