The field of view that gives a parent of parentRadius at distance a
fill fraction of the frame's height.
Solved rather than fixed, because one focal length is not the picture for both ends of what this has to cover: Earth is 1.9° across from Luna and Mars is 42° across from Phobos, a factor of twenty-two. A single lens that framed one of them would put the other off the edges or in a corner as a speck.
Clamped to the slider's own range, and the clamp is doing real work at the
long end: Earthrise at the photograph's framing wants 11.4°, and the range
stops at 20° because the terrain predicate saturates there
(docs/adr/0017-the-lens.md). The picture below 20° is a phase of its own; until then Earth is
smaller in this frame than in the photograph, which is a stated limit rather
than a silent one.
- parentRadiusnumber
- Undocumented
- distancenumber
- Undocumented
- fillnumber
- Undocumented