OpenCV 2.2 window causes problem on OpenGL

Here is very simple code .. Only thing is I repeated same code manytimes for detail debug. Detail info: OpenGL version 3.3.0, Window 7 OS and VS2008, OpenCV 2.2.0.

RenderObject();
//glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS);
Mat image;
image.create(screenHeight,screenWidth, CV_8UC3);
glReadPixels(0, 0, screenWidth, screenHeight, GL_BGR, GL_UNSIGNED_BYTE, (uchar*)image.data);
int error_code1 = glGetError();  // Error Code: 0, NO Error, Also output is good/as expected!
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
int error_code8 = glGetError();  // Error Code: 0, NO Error
//flip(image, image, 0);
//glPopClientAttrib();
const char *title = "glReadPixels Output";
cv::namedWindow(title);  
int error_code2 = glGetError();  // Error Code: 1282, GL_INVALID_OPERATION
imshow(title, image);
int error_code3 = glGetError();  // Error Code: 1282, GL_INVALID_OPERATION
waitKey(5000);
int error_code4 = glGetError();  // Error Code: 0, NO Error
destroyWindow(title);
int error_code5 = glGetError();  // Error Code: 1282, GL_INVALID_OPERATION
image.release();

int error_code6 = glGetError();  // Error Code: 1282, GL_INVALID_OPERATION

glBindFramebufferEX开发者_如何学JAVAT(GL_FRAMEBUFFER_EXT, fboId);
glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT);
glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);

int error_code7 = glGetError();  // Error Code: 1282, GL_INVALID_OPERATION

Something going on here under-the-hood. What is that? ... well at least error_code7 should be 0 (i.e. no error) even if OpenCV window is taking over the default buffer. I tested code with framebuffer object as well as default glut hidden window. Also let me tell you that I must use framebuffer object for my purpose. So, cannt use same default window to draw and show.

code4 is 0 because no new OpenGL operation occured after the previous glGetError(). You should fix the problem were it starts, which is at the first occurence of a non-zero return value from glGetError(). Hence, first thing on the todo list is add a glGetError() below glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

That line should not really cause any troubles, but still, check it. If not, then probably the namedWindow call is messing things up. Which version is your OpenGL context?

When OpenCV was built using 'WITH_QT_OPENGL', above problem occures.

Solutions:

1. Build OpenCV without 'WITH_QT_OPENGL' option. It will completely removes all errors.
2. Or to work around- Re-attach the draw buffer (i.e. glDrawBuffer only with default buffer object or with framebuffer object (FBO) both FBO and texture/render buffer, you could valid this using 'glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);' )