Two visual issues reported: stripes from sides at tilts of view, and
tiles 'hopping' one tile per refetch.
Stripes: caused by gUv.y going OOB at sideways rays where hitPoint.x
is large; CLAMP_TO_EDGE returned the same edge colour across a wide
band, looking like a stripe. Added shader edgeFade that fades OOB
samples smoothly to uBg instead.
Hopping: each refetch shifts centerTile by many tiles (depends on
when in the cycle it fires). With BUFFER_LONG = 1 (refetch at
projLong > halfLong - 1 = 11), the centerTile only ever shifts by
about 1 tile per refetch. Refetches happen more often (~ every
8 sec instead of ~ every 96 sec) but each is tiny.
reverted partial-refetch optimisation: causes ghosting because old
tiles stay at old canvas positions but uGroundCenter moves, so
the shader samples stale content. Better to clear canvas and rely
on edgeFade to hide the brief fog state.
Richard Zink
a3f5bf6084