Return nighttime Sun positions from
get_prague_sky_metadata() below -4.2 degrees so native
renderers can suppress solar radiance while retaining atmospheric
transmission for celestial lights.
Keep Moon disk radiance and color continuous as its center
crosses the horizon. Disk generation retains the finite horizon
attenuation/tint and leaves partial visibility to the renderer, so the
upper limb remains visible until it sets. The legacy
generate_moon_latlong() path now does the same: attenuation
defaults to no center cutoff, and normalization uses the complete disk
before clipping so the remaining limb does not become artificially
bright. Disk visibility is independent of the optional atmosphere
model’s domain.
Add generate_sun_disk() and
generate_moon_disk() for detailed celestial light textures
without an intermediate sky map. Both return linear RGB radiance,
true-north azimuth, elevation, apparent diameter, and an explicit
rectilinear projection. Lunar edge coverage is applied once; no alpha
channel is returned. The Moon reuses existing phase, surface texture,
earthshine, photometry, and atmospheric extinction routines.
prague_rgb_correction, a Prague-only linear RGB
output correction that reduces the small magenta / negative-green tint
observed in generated Prague RGB sky maps. The correction is enabled by
default for Prague RGB output and can be disabled with
prague_rgb_correction = FALSE to recover raw Prague model
RGB values.