Error in rendering two lines !

Hello,
please help me to solve this problem.

I’written an MFC application that use OpenGl according
to the documentation and samples found on several
sources.

I draw two lines (using the glBegin(GL_LINES)…).
The two lines have the same x,y coord but the z is different
line #2 is over the line #1.
Now I use an ortho projection to look at this model from top
(directly down to the Z axis) and the render that I get is
incorrect. It shows a part of line #1 that is under and therefore
NO visible at all !!

Line #1 (Z = 0) --------------
Line #2 (Z = 20) ==============

Eye position V
I get this —=========== ???

I’ve double checked the glortho and glLookat parameters
and everithing is (or at least seems) correct.

Please note that if I remove the graphic acceleration
the problem disappear.

Thanks
Giuseppe

“I’ve double checked the glortho and glLookat parameters and everithing is (or at least seems) correct.”

Could you post them here? They could shed some light on the situation. Also, post your drawing routine (between glBegin and glEnd) so that we can see what you are actually drawing, as opposed to what you think you are drawing.

“Please note that if I remove the graphic acceleration the problem disappear.”

Define “graphic acceleration.” By what process do you remove this that the lines show up correctly?