The programme's item 1 was terrain horizon occlusion, ranked first on the
reasoning that it would make the frame cheaper on the thread that is
actually full. **I measured it before building it, and the premise does
not hold for this renderer**, so this is item 2 instead. The numbers are
in `docs/GRAPHICS.md`: cutting the view distance from 777 yd to 177 —
removing four fifths of the visible world — saves 0.44 ms of a 3.6 ms
frame, p95 is flat at 6.4 ms at every distance, no main-world system in a
steady vista exceeds 0.12 ms/run, and the model cull already takes 6,016
submeshes to 29 drawn. Horizon occlusion can only remove the fraction of
that which sits behind a hill. The reference needed it on a 2004 CPU with
no GPU-side culling; we do not.
What the same harness said about item 2 was the opposite. Before anything
was written: the Elwynn vista renders at a gamma median of 87.6/255 with
1.4% of its pixels under 32, the Goldshire inn at noon at 31.9 with 50.1%
under 32, and the inn's kitchen at **12.8 with 94.5% under 32**. That is
not a dim room, it is a black screen — and the reference has the same
problem, because it has no metering either.
A histogram-and-reduce over the HDR view target, smoothed in the log
domain, applied ahead of the shafts, bloom and glow chain so FFXGlow's
blur — which is built from the scene — sees the same exposed image
everything else does. Two departures from the textbook version, both
forced by what this renderer's pixels mean (the world is drawn in the
reference's gamma convention, which the combine clamps to 1.0):
- The gain has a **floor of 1.0**: it only ever brightens. Aiming at the
exterior's own measured level is what lands it at 1.0 outdoors with no
special case — the vista's median moves 87.6 -> 87.5, and 0.12% of its
pixels with it. Daylight is the one look this client is measured
against and nothing here was worth moving it.
- It has a **ceiling**, which is the tier. The kitchen meters to roughly
24x; uncapped it comes out as daylight, which erases the room instead of
making it readable. Subtle and Full are 2x and 4x: "a dark room you can
see in" and "one you can read in", neither "a lit room".
Measured after: inn noon goes 50.1% -> 4.6% of pixels under 32, the
kitchen 94.5% -> 40.3%, and the vista does not move. **+0.08 ms of GPU**,
nothing on the main thread.
The calibration is the one thing to get right if this is ever re-derived,
and it is written down because I got it wrong first: the aim level is the
level of the scene THIS PASS SEES, not of the screenshot. The glow adds
`w·blur²` downstream, so the finished vista log-averages to 0.0931 linear
and the pass's own input to 0.060. Calibrating against the former aimed
the lane 1.5x high and brightened the daylight exterior it exists to leave
alone — which the vista capture caught immediately.
Two rows on Advanced Graphics, both locales, the blend greyed while there
is no gain to blend; on the Graphics Preset ladder from Medium, in the
shape the other post lanes take. Classic keeps it off, as the reference
has no metering at all.
Verified: ALL GATES GREEN (550 s); `benilla-app --lib` against the install
at the exact 269-failure baseline, set-identical by `comm`.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn
gromandClaude Opus 5
88b6998453