解析obj.文件通过opengl

我有一个对象。文件基本完成。我在最后部分卡住了，有一个错误。

   //load the filename textures (only BMP, R5G6B5 format)
    unsigned int objloader::loadTexture(const char* filename){

unsigned int num;
glGenTextures(1,&num);
SDL_Surface* img=SDL_LoadBMP(filename);
glBindTexture(GL_TEXTURE_2D,num);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,img->w,img->h,0,GL_RGB,GL_UNSIGNED_SHORT_5_6_5,img->pixels);
glTexEnvi(GL_TEXTURE_2D,GL_TEXTURE_ENV_MODE,GL_MODULATE);   
SDL_FreeSurface(img);
texture.push_back(num);
return num;}


objloader::objloader() {
//at default we set all booleans to false, so we don't use anything
ismaterial=false;
isnormals=false;
istexture=false; }

我得到的错误信息是:

错误33错误C2065: 'GL_UNSIGNED_SHORT_5_6_5':未声明的标识符