I have create a system that draws little circles or points in opengl 3 where I click the mouse in a qt opengl widget.
The problem are the coordinates: the circle is not drawed in the position of the mouse when i click.
I divide the point x for the width and the point y for the height for and I have a point from 0 to 1
But how i can trasform these points from 0 to 1 to the opengl coordinates?
i must use the opengl viewport?
or the ortho matrix?