Miter from-center (picket points) + real chamfer preview

- Miter gains a from_center option: pivot at the end CENTRE so it notches a
  corner instead of cutting full width. Add a +angle and a −angle from centre on
  the same end to bring it to a point (picket fence). Feature.from_center;
  geometry.miter_cutter honours it; Joinery panel checkbox (miter only); CLI
  feature --miter-pivot edge|center; wood-feature tool arg; serialization.
- Chamfer preview now shows the actual bevel slivers it removes (board −
  chamfered board), like the miter wedge — instead of a flat face slab.
  _chamfer_removed_mesh, with the face-highlight as fallback.
- tests: center miter notches a corner, two center miters make a point,
  from_center roundtrip, chamfer preview is real geometry. 247 pass.

Re-run gen_wood_tools.py for the voice tool to expose --miter-pivot.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/gen_wood_tools.py

@@ -193,6 +193,7 @@ TOOLS = {
             {"flag": "--rotation", "variable": "rotation", "default": "", "description": "Rotate the feature about its face normal, degrees"},
             {"flag": "--miter", "variable": "miter", "default": "", "description": "kind=miter: angle across the width in degrees (45 for a frame corner)"},
             {"flag": "--bevel", "variable": "bevel", "default": "", "description": "kind=miter: angle through the thickness in degrees (tilted blade)"},
+            {"flag": "--miter-pivot", "variable": "miter_pivot", "default": "", "description": "kind=miter: 'edge' (full-width, default) or 'center' (corner notch — add a +angle and a -angle from center to bring an end to a point, e.g. a picket)"},
         ],
         "code": code(
             'cmd = ws + ["feature", kind]\n'
@@ -200,7 +201,8 @@ TOOLS = {
             'if face: cmd += ["--face", face]\n'
             'for flag, val in [("--along", along), ("--across", across), ("--width", width),\n'
             '                  ("--height", height), ("--depth", depth), ("--diameter", diameter),\n'
-            '                  ("--rotation", rotation), ("--miter", miter), ("--bevel", bevel)]:\n'
+            '                  ("--rotation", rotation), ("--miter", miter), ("--bevel", bevel),\n'
+            '                  ("--miter-pivot", miter_pivot)]:\n'
             '    if val != "": cmd += [flag, str(val)]'
         ),
     },

src/woodshop/cli.py

@@ -177,11 +177,17 @@ def cmd_feature(scene: Scene, args) -> str:
         depth_in=_optlen(args.depth), diameter_in=_optlen(args.diameter),
         rotation_deg=_optdeg(args.rotation),
         miter_deg=_optdeg(getattr(args, "miter", None)),
-        bevel_deg=_optdeg(getattr(args, "bevel", None)))
+        bevel_deg=_optdeg(getattr(args, "bevel", None)),
+        from_center=_miter_pivot(getattr(args, "miter_pivot", None)))
     part = scene.find_feature(feat.id)[0]
     return f"Added {feat.kind} ({feat.id}) to {part.id} on {feat.face}."
 
 
+def _miter_pivot(value):
+    """'center'/'edge' -> bool from_center, or None to leave unchanged."""
+    return None if not value else (str(value).lower().startswith("c"))
+
+
 def cmd_feature_edit(scene: Scene, args) -> str:
     feat = scene.edit_feature(
         args.fid, face=args.face,
@@ -190,7 +196,8 @@ def cmd_feature_edit(scene: Scene, args) -> str:
         depth_in=_optlen(args.depth), diameter_in=_optlen(args.diameter),
         rotation_deg=_optdeg(args.rotation),
         miter_deg=_optdeg(getattr(args, "miter", None)),
-        bevel_deg=_optdeg(getattr(args, "bevel", None)))
+        bevel_deg=_optdeg(getattr(args, "bevel", None)),
+        from_center=_miter_pivot(getattr(args, "miter_pivot", None)))
     return f"Updated feature {feat.id}."
 
 
@@ -392,6 +399,9 @@ def build_parser() -> argparse.ArgumentParser:
         parser.add_argument("--rotation", help="rotate the feature about its face normal (deg)")
         parser.add_argument("--miter", help="miter angle across the width, deg (kind=miter)")
         parser.add_argument("--bevel", help="bevel angle through the thickness, deg (kind=miter)")
+        parser.add_argument("--miter-pivot", dest="miter_pivot", choices=["edge", "center"],
+                            help="miter pivot: 'edge' (full-width cut, default) or 'center' "
+                                 "(corner notch — two make a point)")
 
     sp = sub.add_parser("feature", help="Add a joinery feature (tenon/mortise/hole/slot/miter)")
     sp.add_argument("kind", help="tenon | mortise | hole | slot | dado | rabbet | chamfer | miter")

src/woodshop/geometry.py

@@ -101,10 +101,12 @@ def miter_cutter(feat: Feature, L: float, w: float, t: float):
     else:                                                  # end_b (default)
         block = Pos(L + big / 2, 0, 0) * Box(big, big, big)  # covers x > L
         endx = L
-    # pivot at the edge that stays full length (opposite the angle's sign)
+    if getattr(feat, "from_center", False):
-    py = (-w / 2 if feat.miter_deg >= 0 else w / 2) if feat.miter_deg else 0.0
+        pivot = (endx, 0.0, 0.0)               # pivot at the end CENTRE -> a corner notch
-    pz = (-t / 2 if feat.bevel_deg >= 0 else t / 2) if feat.bevel_deg else 0.0
+    else:                                       # pivot at the edge that stays full length
-    pivot = (endx, py, pz)
+        py = (-w / 2 if feat.miter_deg >= 0 else w / 2) if feat.miter_deg else 0.0
+        pz = (-t / 2 if feat.bevel_deg >= 0 else t / 2) if feat.bevel_deg else 0.0
+        pivot = (endx, py, pz)
     return (Pos(*pivot) * Rot(Z=feat.miter_deg, Y=feat.bevel_deg)
             * Pos(*[-c for c in pivot]) * block)
 

src/woodshop/gui/controller.py

@@ -52,7 +52,8 @@ TOOL_CMD = {
         kind=a["kind"], part=_opt(a.get("part")), face=a.get("face") or "end_b",
         along=_opt(a.get("along")), across=_opt(a.get("across")), width=_opt(a.get("width")),
         height=_opt(a.get("height")), depth=_opt(a.get("depth")), diameter=_opt(a.get("diameter")),
-        rotation=_opt(a.get("rotation")), miter=_opt(a.get("miter")), bevel=_opt(a.get("bevel")))),
+        rotation=_opt(a.get("rotation")), miter=_opt(a.get("miter")), bevel=_opt(a.get("bevel")),
+        miter_pivot=_opt(a.get("miter_pivot")))),
     "wood-feature-delete": lambda a: (cli.cmd_feature_delete, SimpleNamespace(fid=a["fid"])),
     "wood-connect": lambda a: (cli.cmd_connect, SimpleNamespace(anchor=a["anchor"], moving=a["moving"])),
     "wood-explode": lambda a: (cli.cmd_explode, SimpleNamespace(distance=a["distance"])),
@@ -393,7 +394,8 @@ class Controller(QObject):
             across_in=pending.across_in, width_in=pending.width_in,
             height_in=pending.height_in, depth_in=pending.depth_in,
             diameter_in=pending.diameter_in, rotation_deg=pending.rotation_deg,
-            miter_deg=pending.miter_deg, bevel_deg=pending.bevel_deg)
+            miter_deg=pending.miter_deg, bevel_deg=pending.bevel_deg,
+            from_center=pending.from_center)
         self._commit()                # re-tessellates with the new geometry
         self.preview_changed.emit()   # clear the ghost
 

src/woodshop/gui/feature_panel.py

@@ -87,6 +87,11 @@ class FeaturePanel(QWidget):
             self._spins[key] = sp
             form.addRow(label, sp)
         form.insertRow(0, "Face", self.face)
+        self.center_cb = QCheckBox("From centre (corner notch — two make a point)")
+        self.center_cb.setToolTip("Pivot the miter at the end's centre so it notches a corner; "
+                                  "add a +angle and a −angle to bring the end to a point (picket)")
+        self.center_cb.toggled.connect(self._preview)
+        form.addRow("", self.center_cb)
         root.addLayout(form)
 
         self.fit_btn = QPushButton("Fit to mate…")
@@ -163,10 +168,13 @@ class FeaturePanel(QWidget):
             for key, sp in self._spins.items():
                 sp.setValue(getattr(feat, key))
                 self._set_row_visible(sp, key in show)
+            self.center_cb.setChecked(getattr(feat, "from_center", False))
+            self._set_row_visible(self.center_cb, feat.kind == "miter")
         else:
             self.face.setEnabled(False)
             for sp in self._spins.values():
                 self._set_row_visible(sp, True)
+            self._set_row_visible(self.center_cb, False)
         self.hint.setText(_HINTS.get(feat.kind, "") if feat else
                           "Add a feature above, then adjust it here.")
         mate = {"tenon": "mortise", "mortise": "tenon"}.get(feat.kind if feat else "")
@@ -201,6 +209,7 @@ class FeaturePanel(QWidget):
         if self._loading or not self.c.active_feature:
             return
         dims = {key: sp.value() for key, sp in self._spins.items()}
+        dims["from_center"] = self.center_cb.isChecked()
         self.c.set_preview(face=self.face.currentText(), **dims)
 
     def _fit(self) -> None:

src/woodshop/scene.py

@@ -170,6 +170,7 @@ class Feature:
     rotation_deg: float = 0.0   # rotation of the feature about its face normal
     miter_deg: float = 0.0      # 'miter' end cut: angle across the width (0 = square)
     bevel_deg: float = 0.0      # 'miter' end cut: angle through the thickness
+    from_center: bool = False   # miter pivots at the end CENTRE (corner notch) vs an edge
 
     @property
     def is_cut(self) -> bool:
@@ -610,6 +611,8 @@ class Scene:
                    "diameter_in", "rotation_deg", "miter_deg", "bevel_deg"}
         feat = Feature(id=fid, kind=kind, face=face,
                        **{k: float(v) for k, v in dims.items() if k in allowed and v is not None})
+        if dims.get("from_center") is not None:
+            feat.from_center = bool(dims["from_center"])
         if kind == "miter" and feat.miter_deg == 0.0 and feat.bevel_deg == 0.0:
             feat.miter_deg = 45.0                # a sensible default a user can edit
         part.features.append(feat)
@@ -633,6 +636,8 @@ class Scene:
                 if feat.kind in END_KINDS and v not in END_FACES:
                     continue                     # a miter only lives on an end
                 feat.face = v
+            elif k == "from_center":
+                feat.from_center = bool(v)
             elif hasattr(feat, k):
                 setattr(feat, k, float(v))
         self.selection = part.id

src/woodshop/viewer.py

@@ -130,7 +130,10 @@ def feature_preview_mesh(part, feat):
         mesh = pv.Box(bounds=(c[0] - dims[0] / 2, c[0] + dims[0] / 2,
                               c[1] - dims[1] / 2, c[1] + dims[1] / 2,
                               c[2] - dims[2] / 2, c[2] + dims[2] / 2))
-    elif feat.kind == "chamfer":  # can't cheaply preview the bevel — highlight the face
+    elif feat.kind == "chamfer":  # show the bevel slivers it removes; else the face
+        removed = _chamfer_removed_mesh(part, feat)
+        if removed is not None:
+            return removed
         ue, ve, thin = _axis_extent(u, L, w, t), _axis_extent(v, L, w, t), 0.08
         dims = tuple(ue * abs(u[i]) + ve * abs(v[i]) + thin * abs(n[i]) for i in range(3))
         c = fp
@@ -156,6 +159,30 @@ def feature_preview_mesh(part, feat):
     return mesh
 
 
+def _chamfer_removed_mesh(part: Part, feat):
+    """The bevel slivers a chamfer removes (board − chamfered board), placed in
+    world space — so the preview/highlight shows the real bevel, not a face slab.
+    None if the chamfer is a no-op (e.g. over-sized and skipped)."""
+    try:
+        from build123d import Box, Pos
+
+        from .geometry import _apply_chamfer
+        L = part.length_in
+        t, w = part.section_in
+        box = Pos(L / 2, 0, 0) * Box(L, w, t)
+        removed = box - _apply_chamfer(box, feat, L, w, t)
+        mesh = _solid_to_polydata(removed)
+        if mesh.n_points == 0:
+            return None
+    except Exception:
+        return None
+    mesh.rotate_x(part.roll_deg, point=(0, 0, 0), inplace=True)
+    mesh.rotate_y(-part.tilt_deg, point=(0, 0, 0), inplace=True)
+    mesh.rotate_z(part.yaw_deg, point=(0, 0, 0), inplace=True)
+    mesh.translate(part.position_in, inplace=True)
+    return mesh
+
+
 def _add_feature_edges(plotter, mesh, selected: bool) -> None:
     """Overlay a tessellated solid's real edges (corners/holes/chamfers) so it
     reads as crisply as a plain board, without the triangle-mesh noise."""

tests/test_miter.py

@@ -108,3 +108,52 @@ def test_edit_feature_keeps_miter_on_an_end():
     f = s.add_feature("p1", "miter", miter_deg=45)
     s.edit_feature(f.id, face="top")     # invalid for a miter — should be ignored
     assert f.face in ("end_a", "end_b")
+
+
+def test_center_miter_notches_a_corner():
+    """A from-center 45° miter removes a corner triangle (~half the width),
+    unlike the full-width edge cut."""
+    pytest.importorskip("build123d")
+    from woodshop.geometry import miter_cutter
+    from build123d import Box, Pos
+    s = Scene()
+    s.place("2x4", 24)
+    t, w = s.get_part("p1").section_in
+    f = s.add_feature("p1", "miter", miter_deg=45, from_center=True)
+    assert f.from_center is True
+    board = Pos(12, 0, 0) * Box(24, w, t)
+    wedge = board & miter_cutter(f, 24, w, t)
+    b = wedge.bounding_box()
+    assert (b.max.Y - b.min.Y) < 0.75 * w        # only a corner, not full width
+
+
+def test_two_center_miters_make_a_point():
+    """+45 and −45 from centre on the same end bring it to a point (picket)."""
+    pytest.importorskip("build123d")
+    from woodshop.geometry import part_solid
+    s = Scene()
+    s.place("2x4", 24)
+    full = part_solid(s.get_part("p1")).volume
+    s.add_feature("p1", "miter", miter_deg=45, from_center=True)
+    s.add_feature("p1", "miter", miter_deg=-45, from_center=True)
+    pointed = part_solid(s.get_part("p1")).volume
+    assert pointed < full                        # both corners gone -> a point
+
+
+def test_from_center_roundtrips():
+    s = Scene()
+    s.place("2x4", 24)
+    s.add_feature("p1", "miter", miter_deg=45, from_center=True)
+    s2 = Scene.from_dict(json.loads(json.dumps(s.to_dict())))
+    assert s2.get_part("p1").features[0].from_center is True
+
+
+def test_chamfer_preview_shows_removed_bevel():
+    pytest.importorskip("pyvista")
+    pytest.importorskip("build123d")
+    from woodshop.viewer import feature_preview_mesh
+    s = Scene()
+    s.place("2x4", 24)
+    f = s.add_feature("p1", "chamfer", face="top", width_in=0.25)
+    mesh = feature_preview_mesh(s.get_part("p1"), f)
+    assert mesh is not None and mesh.n_points > 0   # the bevel slivers, not a slab