- Total duplication of the code there.  Will extract soon, if appropriate

The same projection is happening already a few lines above

These functions are somewhat arbitrary, but might be a
good starting point for a final form.  Providing these
functions from rendering.h is still only temporary.

My reflexes were for optional arguments, but an overload seems more
correct.

This seems to give a better result for a large variety of different original
model scales.  E.g. average vertex from 'center' of Atlantis is 30-40 whereas
an MP52 is 1ish.

This isn't necessary to render the mesh, but it will be useful
when trying to look up beam emitter and engine emitters to
render in debug mode

When copying behavior from viewport3D we adopted some behavior
from it that doesn't seem necessary for this view