Objects elongated in stereo camera view

[tstellanova]

I've written a simple program that renders a set of cubes. First I tried rendering them with the FirstPerson camera, then FirstPersonStereo. The FirstPerson view looks mostly how I'd expect:

However, the stereo objects are strangely elongated in Y:

(Link to the source code)

This is reproducible on Mac OSX 10.14.6. I'll try on a linux system as well.

[tstellanova]

• Reproduced on two different OSX systems (OpenGL renderer string: Intel HD Graphics 4000 OpenGL Engine).
• The results with FirstPersonStereo camera on Debian are worse. The cubes do not appear at all (the image is just a blank black field). Switching to FirstPerson camera shows the cubes as expected. (OpenGL renderer string:llvmpipe (LLVM 7.0, 128 bits) ie, no GPU acceleration)

Note that the "stereo" example in kiss3d shows a similar behavior (elongated cubes on OSX, blank screen on Debian)