My Screen Is Flipped - ZackWilde27/Z3dPy GitHub Wiki
I built this engine using PyGame and Tkinter as my screen, which is -Y, but some modules like Pyglet and Kivy are +Y, resulting in an image that is upside-down.
To fix this, negate both the FOV and aspect ratio with FindHowVars()
z3dpy.FindHowVars(-90, -(9/16))
It'll print a SetHowVars() function to skip finding.
#z3dpy.FindHowVars(-90, -(9/16))
z3dpy.SetHowVars(0.5624996968047835, -0.999999322742646)
A full explanation of FindHowVars() can be found on the Camera page