Half-width of a body's terminator, in cosine of the incidence angle.
Exported because the sphere has to use the same number. A disk drawn from
a photograph would end at 0.025 on an airless body, because its surface is
smooth at the resolution of the map; terrain is not, and a peak of height h
catches the sun √(2h/R) of a radian past the geometric shadow line. Given
to the ground alone, the two halves of one body fade out over bands differing
by 4.2× on Luna and 6.6× on Iapetus, and a descent crossing the eight-pixel
gate walks straight through that step — which is the third of the three terms
AGENTS.md names as shared.
Widening the disk is the right direction rather than a concession. Its normal map carries real slopes at 2.2× exaggeration on an airless body, and the Moon's terminator seen from space genuinely is ragged over about the angle its relief subtends. On a body with air the wider figure is already the air's own 0.09 and this changes nothing: Earth and Mars were the two that agreed before, and they agree by taking the same branch.
Scalars rather than a Body, because the two callers hold different things —
the palette a Body, buildScene a BodySnapshot — and both already carry
a relief and a radius. The radius is the equatorial one on both sides; the
mean differs from it by under half a percent, which is nothing under a
square root.
- hasAirboolean
- Undocumented
- reliefnumber
- Undocumented
- radiusnumber
- Undocumented