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Author SHA1 Message Date
Tommaso BianchiandClaude Opus 5 b4d6abc57a Design: draw the mate connector as a bear face, with the disc kept behind a preference
Tommaso's decision (snaporca-x0kd): face orientation is hardwired perception -- a toddler reads
a face's roll and verse with no instruction -- so the connector is a face by default and the
conventional disc + roll quadrant stays, selectable, for users who expect it.

  Preferences > Control > Camera > "Draw mate connectors as a face", default ON, key
  design_connector_face_glyph. Read every frame rather than latched, so toggling takes effect on
  the next repaint -- a look you cannot A/B without restarting will not get compared. Verified on
  the rig: unchecking it switches the viewport to the disc live, no restart.

WHY A RELIEF AND NOT A DRAWING. A flat face in the connector's plane foreshortens by
sin(elevation) and collapses at a grazing view exactly like the quadrant it replaces -- measured,
the quadrant falls 89 -> 20 -> 3 -> 0 lit pixels from 47 degrees to edge-on. The relief does not:
its silhouette carries the information. So the glyph is a small shaded solid, painter-sorted,
lambert-shaded against a light fixed in CAMERA space so orbiting does not swing the shading.

THE MUZZLE, AND THE MISTAKE THAT NEARLY LOST IT. It is the only feature standing along +Z, so it
says which way the connector points and it is all that survives edge-on. Two errors on the way:

  1. I built its footprint from height*tan(draft) and got a needle. The real base OVERHANGS the
     crest at both ends (0.062 nose, 0.034 tail) and that overhang is what makes it a wedge. Base
     now lifted straight off the mesh.

  2. Worse, I chased fidelity. Scaled honestly the ridge is 11.3 mm on an 83.3 mm face -- 13.6 %
     of the width -- and at 22-48 px that is a scratch. Tommaso looked at it and could not find
     the muzzle at all, which is the only test that counts. A glyph is a symbol, not a scale
     model, so it now gets two deliberate exaggerations, and COLOUR does most of the work:
     muzzle share of lit pixels at 90/16/6 deg -- body tone 14.8/11.3/17.5 %, accent gold
     18.3/19.2/23.9 %, accent gold at 1.8x width 23.5/25.2/31.2 %.

  The accent is the same gold the disc spends on its roll quadrant, so it stays this tab's "here
  is the direction that matters" colour. Polarity is still on the Z arrow's head; nothing collides.

A connector whose ROLL COULD NOT BE DERIVED keeps the disc treatment whatever the preference says.
A face asserts a definite orientation, and asserting one for a roll that was never derived is the
same confident lie that got billboarding rejected.

Geometry is emitted from the part by docs/design/mate-connectors/emit_glyph_table.py, not
hand-drawn, so glyph and printed connector cannot drift: 12-vertex outline, two eyes, chin bar,
cheek dot, and the snout wedge. Crest 29.0 mm / 6.58 mm drop / 13.1 deg against the review's
28.3 / 6.61 / 13.1 on the B-rep.

Also fixes extract_outline.py, which walked w.Edges: OCC returns them in storage order, not ring
order, ignoring per-edge orientation, so the outline was scrambled -- 45 points and perimeter
6.380 where a clean ring gives 31 and 3.335. Every measurement in the design notes was re-run.
The correction reversed one earlier finding: handedness does NOT read on its own (5.4/8.0/9.1 %
different from its mirror, not the 32-35 % the scrambled ring produced), so the cheek dot is
required rather than merely nice.

RIG-VERIFIED on Xvfb :12 against a 60x40x10 box with a face+edge connector: the face renders with
both eyes, ears, chin bar, cheek dot and a gold muzzle standing proud; the Z arrow degenerates to
its ring when viewed down the axis; and the preference switches to the disc live.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-16 18:26:50 +02:00
Tommaso BianchiandClaude Opus 5 555af98474 Mate connectors: bring the design record and the BearConnector pair into the repo
The connector work has lived outside the code since 2026-08-05, in a workspace repo with no
remote. It is the basis of a decision that now shapes the Design tab, so it belongs here.

  docs/design/mate-connectors/

  DESIGN_MATE_CONNECTORS.md   seven CAD systems surveyed; the frame-pair model this kernel
                              already matches; sections 8b/8c on the glyph, and section 9's
                              four open decisions (D1-D4) still awaiting Tommaso.
  bear.step                   the male, Onshape 2026-08-05T08:27Z, md5 faf228326ee3f971
  BearConnector_Female*.step/.stl, BearConnector_Cutter.step
                              built by make_female.py FROM the real male B-rep rather than
                              re-modelled, so the pocket is complementary by construction
                              including every deliberate asymmetry. Fit measured at exactly
                              0.2000 mm, zero interference, mated hosts proven coplanar.
  BEAR_CONNECTOR_REVIEW.md    the symmetry-group result: identity 81/81 edges, mirror-x 0/81,
                              mirror-y 0/81, rot180Z 0/81, rot90Z 0/81, diagonal 0/81 at
                              0.1 mm. Trivial group, so every PARTIAL view fixes orientation.
  extract_outline.py, simplify_study.py, relief_sheet.py, handedness.py, make_female.py,
  trim_female.py, fit_check.py, verify_trimmed.py, coplanar_test.py + their sheets

THE DECISION THIS SUPPORTS (snaporca-x0kd): the mate connector is drawn as a simplified BEAR
FACE by default, with the standard disc + roll quadrant + Z arrow kept behind a preference.
Face orientation is hardwired perception -- a toddler reads a face's roll and verse with no
instruction -- and no abstract glyph earns that. Measured against the alternative: the disc's
gold quadrant+tick falls 89 -> 66 -> 37 -> 20 -> 3 -> 0 lit pixels as the camera drops from
47 deg to edge-on, and is a shapeless blob by 16 deg.

WHAT THE SIMPLIFICATION STUDY SETTLED (snaporca-wi3z), all measured off the real B-rep:

  The eyes are load-bearing. Same outline and muzzle with the eyes removed stops reading as
  a face at every size. Whatever else goes, they stay.

  45 -> 22 outline vertices with no loss of read at 22 / 32 / 48 px; the muzzle reduces to
  one filled triangle. Three marks plus a cheek dot.

  Drawn FLAT the face fails exactly where the disc fails: in the connector's plane everything
  foreshortens by sin(elevation). Rendered as its real relief instead, lit pixels at 32 px go
  164 -> 210 at 16 deg and 69 -> 120 at 6 deg, and the snout ridge stands proud as a profile
  rather than smearing. The glyph must be a shaded relief, not an outline.

  Handedness already reads without any added mark -- 32 to 35 % of lit pixels differ from the
  mirror, and re-registering by best whole-pixel translation returns offset (0,0), so it is
  real shape asymmetry. But it reads only BY COMPARISON. A dot on one cheek makes it local:
  34.5 / 37.0 / 36.4 %, and unlike uneven eyes (42 %) it does not read as a defect.

Tommaso's calls: it stays a bear, and handedness must read.

The scripts were repointed at the co-located male and extract_outline.py re-run from here to
prove it -- same 45 outline points, same three inner wires, same 3829.5 mm2 back plate.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-16 17:05:09 +02:00