A failed shader compile renders black, and black frames are identical to each
other, so every block scores 0.000 and the row reads as the least varied scene
in the library rather than as a broken one. That happened yesterday — the
subject helpers were declared above the ink they call, GLSL has no forward
declarations, the whole preamble failed to compile, and the gallery reported a
variety of exactly 0.000 with no indication anything was wrong. It is a
particularly bad failure mode for a tool whose entire job is ranking scenes by
that number.
A scene whose first frame has no luminance and no variance is now reported as
broken, with both figures and a pointer to the console, and the row is coloured
apart from the merely flat ones so it cannot be mistaken for a bad score. The
summary counts them separately.
Verified against both answers rather than only the happy one: a healthy Moiré
Grid comes back 0.0365 with no error, and a deliberately broken copy of the same
scene comes back with the diagnosis instead of a zero.
Recorded in HOWTO-variety.md alongside the other instrument traps, since the
general lesson outlives this instance — a broken render produces the most boring
possible numbers rather than an error.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
HOWTO-visualizers.md gets a scene working. Nothing said how to make one look
different from song to song, which is the thing the library is worst at and the
thing every measurement this epic has been about.
Written as evidence rather than advice: each claim carries the number behind it,
so a later change can contradict it. Several already contradict things believed
earlier in the same week.
It records the failures at least as carefully as the wins, because they were more
informative and each looked obviously right beforehand — effects as parameters
inflating a score without changing a picture, concentrating disturbance instead
of adding it, the roster-size theory that a direct sweep found to be nothing, and
reading a form as a metric rather than drawing it. It also documents what the
descriptor cannot see, since half of "why is my score low" is there: brightness,
colour, rotation, quality, and layout for anything that fills the frame.
And it is explicit about which numbers to trust. Direct render comparisons have a
noise floor of zero; aggregate ratios swing enough to have produced four
withdrawn conclusions in one epic.
Ongoing by design, with the open questions listed: coupling has never moved off
zero, fixed-geometry scenes have no known route to variety, and the 0.04 bar was
set against scores that were depressed by a measurement bug.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
