Note to make the asymptote pdf version for the threed image
sphere_and_plane.asy
requires
the -noprc argument
asy -f pdf -noprc sphere_and_plane.asy
The idea for using this argument came from here:
https://sourceforge.net/p/asymptote/discussion/409349/thread/89e478f6/
and the source for the problem may be somehow related to what is discussed there.  "prc" appears to be a mechanism for representing 3D image data.

Note that running
asy -V sphere_and_plane.asy
opens up a viewer that allows you to see the image rotated, etc.
