Eyes: lids, blinking, line of sight

Three parts per eye, stacked the way the mouth is - dark lash ring, sclera
inside it, iris inside that, square pupil in the iris. A blink then costs
nothing: when the lid shuts the traced ring goes flat and the lash line
collapses to a lens, which is a closed eye, drawn correctly, for free.

Lids are a FEATURE, rotoscoped like the mouth: head-local, a key on every
frame, the same contour avg knob. The iris is a PRIMITIVE - a disc at a
quantised position - and that is where the stylisation lives.

Line of sight. Gaze is the iris centre relative to the midpoint of the eye's
two corners, in units of corner distance. Both corners are in RIGID, so the
origin and the scale are immune to the performance being measured; against the
lid ring's centroid instead, every blink would drag the origin down and fake a
glance at the floor on exactly the frames where the eye is most visible. Both
eyes share one gaze - at this size the difference between the two measurements
is noise, not vergence, and independent per-eye noise reads as wall-eyed
immediately. Openness stays per-eye so a wink survives.

Gaze is then quantised to a pixel grid with a dwell, which is not a
stylisation imposed on the truth: real eyes move in saccades, and the smooth
drift left in the measurement is tracker noise plus head-compensation error.
Snapping to a grid removes the noise and recovers the saccade in one operation.

The iris is placed in the frame of the already-smoothed, already-subsampled lid
ring - slots 0 and 8 of a 16-slot ring are the corners, and subsampling to any
even budget keeps them at 0 and n/2 - so it cannot drift relative to its own
eye. Size is authored from the take mean, never remeasured per frame: a radius
that breathes by a fraction of a pixel flickers a pixel on and off around the
whole silhouette. iris anchor toggles steady/free/locked, because how much the
eye wanders turns out to be an aesthetic choice and not only a correctness one.

Blinking gets hysteresis and a dwell like the teeth, plus one knob they do not
have: blink hold. A blink is one frame at 12fps and a single frame of closed
eye reads as a dropped frame, so once the eye shuts it stays shut long enough
to be legible. Detection accuracy is not the problem; legibility is.

The pupil is a square because at three pixels a circle is a plus sign with the
corners gnawed off, and it changes shape as it moves. Drawn from a rounded
centre shared with the iris so it is exactly its nominal size on every frame.

Iris/pupil clip by colour key against the indexed buffer, the way Animator Pro
would: the lid crops the iris at extreme gaze for free, so nothing has to clamp
the gaze, which would flatten the performance at the extremes that carry it.

Which iris block belongs to which eye is RESOLVED from geometry, not declared.
A swap looks almost right - each eye still has a disc roughly where it belongs
- so it survives an eyeball and then reads as a subtly wall-eyed character
forever. Voted across every frame; the test feeds a deliberately swapped track.

Also: exposure. Aesthetic sparseness was set by the extraction rate, which made
the timing a property of a directory of PNGs - auditioning 12 against 24 meant
re-ripping and re-detecting the whole clip. It is now a render-time grid, on
1s/2s/3s/4s, so the dense track keeps everything and the audio clock is
untouched. The take format already carried an exposure field; it was never
driven. Everything rides the same grid, because a head cutting on the odd
frames while the mouth cuts on the even ones reads as two performances laid
over each other.

41 -> 91 assertions. The load-bearing new ones: the iris pairing follows a
swapped track, a blink does not fake a change of gaze, a stencilled disc cannot
spill past its clip, a 3px pupil is 3x3 at every sub-pixel centre, and exposure
never reads a pose from the future.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

index.html

@@ -63,6 +63,21 @@
   <input type="text" id="framedir" value="frames" size="7" title="frame directory">
   <button id="btn-frames">Load frames</button>
   <button id="btn-play">Play</button>
+  <select id="irisAnchor" title="what the iris hangs off">
+    <option value="steady" selected>iris: steady</option>
+    <option value="free">iris: free</option>
+    <option value="locked">iris: locked</option>
+  </select>
+  <select id="gazeOrigin" title="what counts as looking straight ahead">
+    <option value="median" selected>origin: median</option>
+    <option value="neutral">origin: neutral f</option>
+  </select>
+  <select id="exposure" title="exposure — how often the picture gets a new drawing">
+    <option value="1" selected>on 1s</option>
+    <option value="2">on 2s</option>
+    <option value="3">on 3s</option>
+    <option value="4">on 4s</option>
+  </select>
   <select id="speed" title="playback speed"><option value="1">1x</option><option value="0.5">½x</option><option value="0.25">¼x</option></select>
   <audio id="audio" controls hidden style="height:28px;vertical-align:middle"></audio>
   <button id="btn-keepall">Keep all</button>
@@ -86,18 +101,22 @@
     <div class="panel">
       <h2>source + landmarks</h2>
       <canvas id="cv-source"></canvas>
-      <div class="legend">outer lip <b style="color:#4ade80">—</b> · inner lip <b style="color:#f87171">—</b></div>
+      <div class="legend">outer lip <b style="color:#4ade80">—</b> · inner lip <b style="color:#f87171">—</b> ·
+        lids <b style="color:#60a5fa">—</b> · iris <b style="color:#fbbf24">—</b></div>
     </div>
     <div class="panel">
       <h2>stabilised (head-local)</h2>
       <canvas id="cv-stab"></canvas>
-      <div class="legend">should sit still except the mouth · grey = held plate outline<br>dark green ghost = unshifted mouth when lead ≠ 0</div>
+      <div class="legend">should sit still except the mouth and eyes · grey = held plate outline<br>
+        dark green ghost = unshifted mouth when lead ≠ 0 · red lid ring = blink</div>
     </div>
     <div class="panel">
       <h2>flat render — 320×200 indexed</h2>
       <canvas id="cv-render"></canvas>
       <div class="legend" id="framelabel"></div>
       <div class="legend">audio drives the clock — dropped frames, never drift<br>
+        <b>exposure</b> holds the picture on a grid: rip at 24, render on 2s for
+        12. The dense track and the audio are untouched, so it is reversible<br>
         plate representation: <kbd>B</kbd> cycles · photo modes are <b>registered</b>
         into raster space, so tracing them lands on the mouth</div>
     </div>
@@ -132,6 +151,16 @@
       <label class="ctl"><span>teeth vertices</span><input type="range" id="teethVerts" min="5" max="20" value="10"><output id="teethVertsv"></output></label>
       <label class="ctl"><span>teeth avg ±f</span><input type="range" id="teethSmooth" min="0" max="4" value="1"><output id="teethSmoothv"></output></label>
       <label class="ctl"><span>teeth dwell</span><input type="range" id="teethDwell" min="0" max="6" value="1"><output id="teethDwellv"></output></label>
+      <label class="ctl"><span>eye vertices</span><input type="range" id="eyeVerts" min="4" max="12" step="2" value="8"><output id="eyeVertsv"></output></label>
+      <label class="ctl"><span>lash line</span><input type="range" id="lashPx" min="0" max="3" value="1"><output id="lashPxv"></output></label>
+      <label class="ctl"><span>blink cut</span><input type="range" id="blinkCut" min="20" max="300" value="130"><output id="blinkCutv"></output></label>
+      <label class="ctl"><span>blink hold ±f</span><input type="range" id="blinkHold" min="1" max="5" value="2"><output id="blinkHoldv"></output></label>
+      <label class="ctl"><span>blink dwell</span><input type="range" id="blinkDwell" min="0" max="4" value="0"><output id="blinkDwellv"></output></label>
+      <label class="ctl"><span>gaze gain</span><input type="range" id="gazeGain" min="50" max="400" value="100"><output id="gazeGainv"></output></label>
+      <label class="ctl"><span>gaze step</span><input type="range" id="gazeStep" min="0" max="6" value="2"><output id="gazeStepv"></output></label>
+      <label class="ctl"><span>gaze dwell</span><input type="range" id="gazeDwell" min="0" max="6" value="2"><output id="gazeDwellv"></output></label>
+      <label class="ctl"><span>iris size</span><input type="range" id="irisSize" min="20" max="70" value="42"><output id="irisSizev"></output></label>
+      <label class="ctl"><span>pupil</span><input type="range" id="pupilPx" min="0" max="7" value="3"><output id="pupilPxv"></output></label>
       <label class="ctl"><span>suggest tolerance</span><input type="range" id="tol" min="2" max="60" value="14"><output id="tolv"></output></label>
       <div class="legend">
         <b>mouth lead</b> shifts the performance tracks earlier (positive) against
@@ -150,10 +179,28 @@
         brightness; <b>prefer upper</b> biases component choice toward the top of
         the cavity, where teeth are and the tongue is not.
         <b>dwell</b> is how many frames a presence change must persist.<br>
+        <b>blink cut</b> is lid gap over corner distance — normalised, so one
+        value carries across takes. <b>blink hold</b> is the minimum length of a
+        blink: a real blink is one frame at 12fps and a single frame of closed
+        eye reads as a dropout, so it is extended to a beat.
+        <b>pupil</b> is a square, in whole pixels, 0 to turn it off: at this size
+        a circle of radius 1.5 is a plus sign with the corners gnawed off and it
+        changes shape as it moves, where a square stays the mark you drew.<br>
+        <b>gaze step</b> is the grid the iris snaps to, in raster pixels, and
+        <b>gaze dwell</b> is how long a new cell must hold — together they turn
+        drift into saccades. <b>gaze gain</b> exaggerates or damps the throw;
+        measured excursion is small and a character usually wants more of it.<br>
         <b>suggest tolerance</b> only affects the Suggest button: max head movement
         allowed before a new drawing is required.
       </div>
     </div>
+    <div class="panel" style="flex:0 1 170px">
+      <h2>gaze field</h2>
+      <canvas id="cv-gaze"></canvas>
+      <div class="legend" id="eyeinfo" style="white-space:pre-line"></div>
+      <div class="legend">green = every cell the iris visits in the take ·
+        grey = raw · amber = where it is now, quantised</div>
+    </div>
     <div class="panel" style="flex:0 1 190px">
       <h2>teeth measurement</h2>
       <div id="cv-teeth"></div>