opengl: Change the origin to upper left corner

Question

I am having trouble setting the openGL origin to the upper left corner of the view. So, in my window resize handler, I do something as;

// ox and oy are some         


        

Answer 1

By flipping around the y-axis you flipped the chirality of the world space. Which means that the winding of your faces comes out differently. CCW becomes CW and vice versa. Most likely you have face culling enabled, so to account for the chirality flip you have to swap CCW for CW face culling.