feat(p40): 乌篷船篷面实心拱形重绘与像素回归

- make-cc0-art.py 重绘 boat 篷面为实心拱形竹篷：拱线以下逐列实心填充，
  连续脊线高光跨越两半在瓦片边界相接，肋骨/端盖/甲板阴影收边（原 1px 竖柱
  栅栏式画法改为整片拱面）
- 重生成 Assets/cc0-tiles.png（同参数逐字节稳定）
- P40ArtTests 新增 BoatAwningIsASolidArchWithAContinuousRidge 像素级断言：
  脊线无透明断列、拱下每列有实心竹色、左右两半拱顶同高

属 P40 整改的篷面实心 + 回归部分。

1 files changed, 79 insertions, 41 deletions

diff --git a/scripts/make-cc0-art.py b/scripts/make-cc0-art.py
index 351c20a..3290fa0 100644
--- a/scripts/make-cc0-art.py
+++ b/scripts/make-cc0-art.py
@@ -235,6 +235,7 @@ PAVE_JOINT = (72, 72, 70, 255)
 BAMBOO = (44, 58, 34, 255)
 BAMBOO_HI = (86, 104, 62, 255)
 BAMBOO_RIB = (28, 38, 22, 255)
+BAMBOO_DARK = (22, 30, 17, 255)
 RED_LANTERN = (208, 58, 46, 255)
 RED_LANTERN_HI = (238, 104, 84, 255)
 RED_LANTERN_DARK = (150, 34, 28, 255)
@@ -284,54 +285,91 @@ def draw_bridge_end(c, ox):
 def draw_boat(c, ox, right_half):
     """Wu Peng boat half (2 tiles wide): dark hull + tall curved bamboo awning.
 
-    P40: the boat was scaled up to fill the 64x32 footprint so the wu peng (拱形
-    竹篷) reads at a glance from a bridge or bank. Each half is 32px wide; the
-    awning is a tall elliptical bamboo arch spanning the middle of the 2-tile
-    boat with visible ribs, and the hull is a solid dark band with an upturned
-    bow/stern tip. The gunwale sits 8px down, leaving open water ripple above.
+    P40 fix: the awning is a *solid* arched span, not a row of 1px posts. For
+    every column across the awning the tile fills a horizontal band from the
+    arch top y(x) down to the deck line, so the silhouette reads as one filled
+   拱形竹篷. The ridge (arch top plateau) is a continuous highlight band with no
+    transparent break. Each half is 32px wide; the right half mirrors the left,
+    so the two halves join into a single continuous arch with the ridge meeting
+    at the tile boundary (no broken arc).
+
+    Left half local profile y(x):
+      x < 1      : outside the awning (bow only)
+      x in [1,6) : rising arc 9,7,5,3,1 (stepped outer end)
+      x in [6,31]: ridge plateau y=1
+    The right half mirrors it (local lx -> 31-lx). The stepped end is capped with
+    one BAMBOO_DARK column; the hull has plank seams (y=14/22) and a waterline.
     """
     c.fill(ox, 0, 32, 32, CLEAR)
-    # --- Hull: solid dark band spanning the full cell, 8px down to 30px. ---
+    deck_y = 9
+
+    def top_at(x):
+        """Left-half local arch top row for column x, or None outside the awning."""
+        if x < 1:
+            return None
+        if x < 6:
+            # Rounded rise: 9,7,5,3,1 across x=1..5 so the ridge plateau starts at x=6.
+            return 9 - 2 * (x - 1)
+        return 1
+
+    # --- Hull: solid dark band, 8px down to 30px, with a raised bow/stern tip. ---
     c.fill(ox, 8, 32, 22, BOAT_HULL)
     c.fill(ox, 8, 32, 2, BOAT_HULL_DARK)
     c.fill(ox, 28, 32, 2, BOAT_HULL_DARK)
-    # --- Awning (wu peng): tall bamboo arch over the middle of the 2-tile boat. ---
-    # Arc rises from the outer edge up to a high ridge, so both halves join into
-    # one continuous arch. Left half: low at x=0, ridge near the inner (right) edge.
-    arc = [
-        (0, 12), (2, 9), (4, 6), (6, 4), (8, 3),
-        (10, 2), (12, 1), (14, 1), (16, 1), (18, 1),
-        (20, 1), (22, 1), (24, 2), (26, 3), (28, 4),
-        (30, 5), (32, 6),
-    ]
+    # Plank seams (y=14 / y=22) + waterline (bottom rows read as below the water).
+    c.hline(ox, 14, 32, BOAT_HULL_DARK)
+    c.hline(ox, 22, 32, BOAT_HULL_DARK)
+    c.hline(ox, 29, 32, BOAT_HULL_DARK)
+    c.hline(ox, 30, 32, BOAT_HULL_DARK)
     if not right_half:
-        # Left half: bow tip at the far left, rising; awning covers inner 20px.
-        for i in range(24):
-            half = 4 + i // 2
-            c.fill(ox, 8 + i, min(32, half), 1, BOAT_HULL)
-        c.fill(ox, 6, 4, 3, BOAT_HULL_DARK)
-        c.fill(ox, 5, 2, 3, BOAT_HULL)
-        for (x, top) in arc:
-            c.fill(ox + x, top, 1, 32 - top, BAMBOO)
-        c.fill(ox + 12, 1, 20, 2, BAMBOO_HI)
-        for rib in (14, 18, 22, 26, 30):
-            c.fill(ox + rib, 1, 1, 30, BAMBOO_RIB)
-        c.fill(ox + 12, 30, 20, 2, BAMBOO_RIB)
-        c.fill(ox + 12, 6, 2, 24, BAMBOO_HI)
+        c.fill(ox, 5, 3, 3, BOAT_HULL)
+        c.fill(ox, 6, 3, 2, BOAT_HULL_DARK)
+        awning_columns = list(range(1, 32))
+        rib_columns = [14, 20, 26]
+        cap_columns = [1]  # stepped outer end of the awning
+
+        def local_top(lx):
+            return top_at(lx)
     else:
-        # Right half: stern tip at the far right, mirrored continuous hull.
-        for i in range(24):
-            half = 4 + i // 2
-            c.fill(ox + 32 - min(32, half), 8 + i, min(32, half), 1, BOAT_HULL)
-        c.fill(ox + 28, 6, 4, 3, BOAT_HULL_DARK)
-        c.fill(ox + 30, 5, 2, 3, BOAT_HULL)
-        for (x, top) in arc:
-            c.fill(ox + 31 - x, top, 1, 32 - top, BAMBOO)
-        c.fill(ox, 1, 20, 2, BAMBOO_HI)
-        for rib in (1, 5, 9, 13, 17):
-            c.fill(ox + rib, 1, 1, 30, BAMBOO_RIB)
-        c.fill(ox, 30, 20, 2, BAMBOO_RIB)
-        c.fill(ox + 18, 6, 2, 24, BAMBOO_HI)
+        c.fill(ox + 29, 5, 3, 3, BOAT_HULL)
+        c.fill(ox + 28, 6, 3, 2, BOAT_HULL_DARK)
+        awning_columns = list(range(0, 31))
+        rib_columns = [5, 11, 17]
+        cap_columns = [29]  # mirrored stepped outer end
+
+        def local_top(lx):
+            return top_at(31 - lx)
+
+    # --- Solid arched span: each column fills from the arch line to the deck. ---
+    for lx in awning_columns:
+        t = local_top(lx)
+        if t is None:
+            continue
+        c.fill(ox + lx, t, 1, deck_y - t + 1, BAMBOO)
+    # Continuous ridge highlight: rows t..t+1 across the whole awning (no break).
+    for lx in awning_columns:
+        t = local_top(lx)
+        if t is None:
+            continue
+        c.fill(ox + lx, t, 1, min(2, deck_y - t + 1), BAMBOO_HI)
+    # Bamboo ribs below the ridge (texture only; ridge band stays continuous).
+    for lx in rib_columns:
+        t = local_top(lx)
+        if t is None or t + 2 > deck_y:
+            continue
+        c.fill(ox + lx, t + 2, 1, deck_y - t - 1, BAMBOO_RIB)
+    # Stepped end cap: one dark column closing the outer end of the awning.
+    for lx in cap_columns:
+        t = local_top(lx)
+        if t is None:
+            continue
+        c.fill(ox + lx, t, 1, deck_y - t + 1, BAMBOO_DARK)
+    # Deck shadow where the awning meets the hull.
+    for lx in awning_columns:
+        t = local_top(lx)
+        if t is None:
+            continue
+        c.set(ox + lx, deck_y, BAMBOO_RIB)
 
 
 def draw_paving(c, ox):