feat: 2 m placeholder pattern zones on lining, station/pattern readout in viewer (Task 5)

No pattern-to-station data exists in the drawings. Per user decision
(2026-10-21) the modelled range 4+745..5+480 is split into 2 m segments with
arbitrary pattern names, marked placeholder in CSV, meta and viewer, to be
replaced later. Ring step reduced to 1 m so that the 2 m segments align.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A5Cun3RHQKna9qxE6ybZ4A

scripts/build_skeleton.py

@@ -30,7 +30,7 @@ R1, R_OUT, R_EX = 6.982, 7.282, 7.402           # m (mm / 1000)
 CROWN_A = 6.615                                  # m above road
 CENTRE_C = CROWN_A - R1                          # arch centre height above road (m)
 S0, S1 = 4745, 5480                              # modelled range (fully determined)
-DS = 5.0                                         # station step for rings (m)
+DS = 1.0                                         # station step for rings (m); pattern segments are 2 m
 ANG = np.radians(np.linspace(40.0, 140.0, 41))   # arch arc, right springline -> left
 
 def read_centre():
@@ -80,18 +80,33 @@ def ring_world(R, s):
     P = np.column_stack([x - ORIGIN[0] + xs * nx, y - ORIGIN[1] + xs * ny, zr + zs])
     return P
 
-def make_band(R, color, name):
+PAL = {"NP-4AD-1-D-2": (231, 111, 81, 255), "NP-4BD-1-D-2": (244, 162, 97, 255),
+       "NP-5AE-1-WL-4": (233, 196, 106, 255), "NP-5BE-1-WL-4": (138, 177, 125, 255),
+       "NP-6A": (42, 157, 143, 255), "NP-6B": (38, 70, 83, 255)}
+ZONES = [(int(r["seg_from"]), int(r["seg_to"]), r["pattern"], r["status"])
+         for r in csv.DictReader(open(f"{ROOT}/data/pattern_zones_placeholder.csv", encoding="utf-8"))]
+
+def pattern_of(sta):
+    for a, b, pat, _ in ZONES:
+        if a <= sta < b:
+            return pat
+    return ZONES[-1][2]
+
+def make_band_pattern(R, name):
     rings = [ring_world(R, s) for s in stations]
     n = len(rings[0]); m = len(rings)
     V = np.vstack(rings)
-    F = []
+    F, C = [], []
     for i in range(m - 1):
+        col = PAL[pattern_of(stations[i])]
         for j in range(n - 1):
             a = i * n + j; b = a + 1; c = a + n; d = c + 1
             F += [[a, b, c], [b, d, c]]
+            C += [col, col]
     mesh = trimesh.Trimesh(vertices=V, faces=np.array(F), process=False)
-    mesh.visual.face_colors = np.tile(np.array(color, dtype=np.uint8), (len(F), 1))
+    mesh.visual.face_colors = np.array(C, dtype=np.uint8)
     mesh.metadata["name"] = name
+    mesh.metadata["ring_points"] = n
     return mesh
 
 def make_ribbon(z_fn, half_w, color, name):
@@ -111,9 +126,24 @@ def make_ribbon(z_fn, half_w, color, name):
     mesh.metadata["name"] = name
     return mesh
 
+def make_band(R, color, name):
+    """uniform-colour band (excavation outline)."""
+    rings = [ring_world(R, s) for s in stations]
+    n = len(rings[0]); m = len(rings)
+    V = np.vstack(rings)
+    F = []
+    for i in range(m - 1):
+        for j in range(n - 1):
+            a = i * n + j; b = a + 1; c = a + n; d = c + 1
+            F += [[a, b, c], [b, d, c]]
+    mesh = trimesh.Trimesh(vertices=V, faces=np.array(F), process=False)
+    mesh.visual.face_colors = np.tile(np.array(color, dtype=np.uint8), (len(F), 1))
+    mesh.metadata["name"] = name
+    return mesh
+
 parts = [
-    make_band(R_OUT, (190, 190, 186, 255), "lining_outer_R7282"),
-    make_band(R1,    (235, 235, 230, 255), "lining_inner_R6982"),
+    make_band_pattern(R_OUT, "lining_outer_R7282"),
+    make_band_pattern(R1, "lining_inner_R6982"),
     make_band(R_EX,  (150, 120, 90, 110),  "excavation_R7402"),
     make_ribbon(lambda s: float(np.interp(s, dg_s, dg_v)), 5.0, (70, 70, 75, 255), "road_surface_계획고"),
     make_ribbon(lambda s: float(np.interp(s, gl_s, gl_v)), 20.0, (110, 150, 90, 200), "ground_GL_지반고"),
@@ -138,6 +168,9 @@ checks["road_z_5480_m"] = round(float(np.interp(S1, dg_s, dg_v)), 3)
 L_chord = float(np.sum([math.dist(cn[i, 1:], cn[i + 1, 1:]) for i in range(len(cn) - 1)]))
 checks["plan_chord_length_total_m (4+700..5+500)"] = round(L_chord, 3)
 checks["station_range_modelled"] = f"{S0} .. {S1} (ring step {DS} m, {len(stations)} rings)"
+checks["pattern_zones (2 m, placeholder)"] = len(ZONES)
+checks["pattern_coverage_all_stations"] = bool(all(pattern_of(x) in PAL for x in stations))
+checks["pattern_counts"] = {k: sum(1 for z in ZONES if z[2] == k) for k in PAL}
 checks["glb_bytes"] = int(__import__("os").path.getsize(glb))
 reload = trimesh.load(glb)
 checks["glb_reload_geometries"] = len(reload.geometry)
@@ -154,6 +187,9 @@ meta = {
                      "centreline and grade linearly interpolated between nodes",
                      "superelevation sign convention assumed (z += S/100 * x, x = left of tangent)"],
   "layers": [p.metadata["name"] for p in parts],
+  "ring_step_m": DS, "ring_points": int(parts[0].metadata["ring_points"]), "first_station": S0,
+  "pattern_status": "PLACEHOLDER: 2 m 임의 배정. 실제 측점 구간 아님 (사용자 결정 2026-10-21). data/pattern_zones_placeholder.csv 를 수정 후 재빌드",
+  "patterns": [{"from": a, "to": b, "pattern": pat} for a, b, pat, _ in ZONES],
   "open": ["4+700~4+745 and 5+480~5+500 excluded ([미확정])", "pattern zones (03-003~008) pending Task 5",
            "lining details (04-004~009) pending Task 6"]
 }