fix(sky): seamless night-sky star lattice — no face seams, no flare, round pixel-exact stars

The first night-sky gate (2026-08-23 screenshot) showed three defects:
glowing beams along the cube-face boundaries (fwidth blowup where
adjacent pixels land on different faces lights every neighbourhood star
solid), diffraction-spiked standouts the user rejects ('that is in a
photo only, not in real sky'), and ellipse-stretched stars from scalar
length(fwidth) sizing at oblique view angles.

One rewrite removes all three: stars now live on a seamless 3D lattice
over the unit sphere (no faces, so no seams by construction), each star
resolved through an exact tangent-plane -> screen-pixel 2x2 solve of
the direction derivatives (perfectly round, true pixel sizing at every
view angle, sharper cores), spikes deleted in favour of a soft round
halo on the bright tiers. Guard test updated to pin the new anchors and
forbid both fwidth-face grids and spikes; sky.frag.spv re-pinned.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Erik 2026-08-23 18:00:28 +02:00
parent 508cefdeb1
commit b8cfee6d08
5 changed files with 58 additions and 46 deletions