From 3cd46213621e07632c41285bba2a4de34a1dceac Mon Sep 17 00:00:00 2001
From: Ash Ketchum <no-reply@sl0p.foo>
Date: Wed, 15 Jul 2026 12:05:18 +0200
Subject: tools: render_overworld.py - build seamless Kanto map from source

Ground-truth overworld generator, no emulator. Parses map_const dimensions, the
per-map headers (tileset + connections with their alignment OFFSET), the .blk
block data, .bst blocksets (4x4 tile indices) and .2bpp tilesets, renders every
map full-size, and places them by the connection-offset math (BFS from Pallet):
  north:(ax+o,ay-Bh) south:(ax+o,ay+Ah) west:(ax-Bw,ay+o) east:(ax+Aw,ay+o)
Produces a coherent 170x180-block (5440x5760px) Kanto overworld from 36 connected
maps -- confirming connections join maps along shared edges with an offset, not
as independent centered screens.
---
 tools/render_overworld.py | 132 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 tools/render_overworld.py

(limited to 'tools')

diff --git a/tools/render_overworld.py b/tools/render_overworld.py
new file mode 100644
index 00000000..cf4de255
--- /dev/null
+++ b/tools/render_overworld.py
@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+"""render_overworld.py — build the seamless Kanto overworld straight from the
+PKY source data (no emulator). Ground truth for how maps connect.
+
+  maps/<Label>.blk            raw W*H block indices
+  gfx/blocksets/<t>.bst       16 bytes/block = 4x4 tile indices
+  gfx/tilesets/<t>.2bpp       16 bytes/tile  = 8x8 2bpp
+  data/maps/headers/*.asm     tileset + connections (dir, target, offset)
+  constants/map_constants.asm map_const NAME, W, H   (blocks)
+
+Placement (global block coords, top-left of each map), A --dir(offset o)--> B:
+  north: (ax+o, ay-Bh)   south: (ax+o, ay+Ah)
+  west : (ax-Bw, ay+o)   east : (ax+Aw, ay+o)
+"""
+import os, re, sys, glob
+from PIL import Image
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+def P(*a): return os.path.join(ROOT, *a)
+
+# --- map dimensions (blocks) -------------------------------------------------
+dims = {}
+for m in re.finditer(r'map_const\s+(\w+),\s*(\d+),\s*(\d+)', open(P('constants/map_constants.asm')).read()):
+    dims[m.group(1)] = (int(m.group(2)), int(m.group(3)))
+
+# --- tileset const order  <->  tileset name ----------------------------------
+tconsts = re.findall(r'^\s*const\s+(\w+)', open(P('constants/tileset_constants.asm')).read(), re.M)
+tnames  = re.findall(r'^\s*tileset\s+(\w+),', open(P('data/tilesets/tileset_headers.asm')).read(), re.M)
+const2tileset = dict(zip(tconsts, tnames))    # OVERWORLD -> Overworld
+
+# --- tileset name -> (bst path, 2bpp path) -----------------------------------
+tblk, tgfx = {}, {}
+pend_blk, pend_gfx = [], []
+for line in open(P('gfx/tilesets.asm')):
+    mb = re.match(r'\s*(\w+)_Block::(?:\s*INCBIN\s+"([^"]+)")?', line)
+    mg = re.match(r'\s*(\w+)_GFX::(?:\s*INCBIN\s+"([^"]+)")?', line)
+    if mg:
+        pend_gfx.append(mg.group(1))
+        if mg.group(2):
+            for n in pend_gfx: tgfx[n] = mg.group(2)
+            pend_gfx = []
+    elif mb:
+        pend_blk.append(mb.group(1))
+        if mb.group(2):
+            for n in pend_blk: tblk[n] = mb.group(2)
+            pend_blk = []
+
+# --- parse every map header: label, const, tileset, connections --------------
+maps = {}            # const -> dict(label, tileset, conns=[(dir,tgtconst,off)])
+const2label = {}
+for f in glob.glob(P('data/maps/headers/*.asm')):
+    txt = open(f).read()
+    h = re.search(r'map_header\s+(\w+),\s*(\w+),\s*(\w+),', txt)
+    if not h: continue
+    label, const, tileset = h.group(1), h.group(2), h.group(3)
+    const2label[const] = label
+    conns = [(m.group(1), m.group(3), int(m.group(4)))
+             for m in re.finditer(r'connection\s+(\w+),\s*(\w+),\s*(\w+),\s*(-?\d+)', txt)]
+    maps[const] = dict(label=label, tileset=tileset, conns=conns)
+
+# --- blockset / tileset caches -----------------------------------------------
+SHADE = [(255,255,255),(168,168,168),(80,80,80),(0,0,0)]
+_bst, _gfx, _rendered = {}, {}, {}
+def blockset(name):
+    if name not in _bst: _bst[name] = open(P(tblk[name]),'rb').read()
+    return _bst[name]
+def tileset_gfx(name):
+    if name not in _gfx: _gfx[name] = open(P(tgfx[name]),'rb').read()
+    return _gfx[name]
+def tile_img(gfx, idx):
+    px = []
+    o = idx*16
+    for row in range(8):
+        b1, b2 = gfx[o+row*2], gfx[o+row*2+1]
+        for col in range(8):
+            v = ((b1>>(7-col))&1) | (((b2>>(7-col))&1)<<1)
+            px.append(SHADE[v])
+    im = Image.new('RGB',(8,8)); im.putdata(px); return im
+
+def render_map(const):
+    if const in _rendered: return _rendered[const]
+    label = maps[const]['label']; tname = const2tileset[maps[const]['tileset']]
+    w,h = dims[const]
+    blk = open(P('maps', label+'.blk'),'rb').read()
+    bs, gfx = blockset(tname), tileset_gfx(tname)
+    img = Image.new('RGB',(w*32,h*32),(0,0,0))
+    for br in range(h):
+        for bc in range(w):
+            if br*w+bc >= len(blk): continue
+            block = blk[br*w+bc]
+            for ty in range(4):
+                for tx in range(4):
+                    ti = bs[block*16 + ty*4 + tx]
+                    img.paste(tile_img(gfx,ti), (bc*32+tx*8, br*32+ty*8))
+    _rendered[const] = img
+    return img
+
+# --- BFS placement from PALLET_TOWN ------------------------------------------
+pos = {'PALLET_TOWN': (0,0)}
+q = ['PALLET_TOWN']
+while q:
+    a = q.pop(0)
+    if a not in maps: continue
+    ax, ay = pos[a]; aw, ah = dims[a]
+    for d, b, o in maps[a]['conns']:
+        if b in pos or b not in dims: continue
+        bw, bh = dims[b]
+        if   d == 'north': pos[b] = (ax+o, ay-bh)
+        elif d == 'south': pos[b] = (ax+o, ay+ah)
+        elif d == 'west':  pos[b] = (ax-bw, ay+o)
+        elif d == 'east':  pos[b] = (ax+aw, ay+o)
+        else: continue
+        q.append(b)
+
+placed = [c for c in pos if c in maps and os.path.exists(P('maps', maps[c]['label']+'.blk'))]
+minx = min(pos[c][0] for c in placed); miny = min(pos[c][1] for c in placed)
+maxx = max(pos[c][0]+dims[c][0] for c in placed)
+maxy = max(pos[c][1]+dims[c][1] for c in placed)
+W, H = (maxx-minx)*32, (maxy-miny)*32
+print(f"placed {len(placed)} maps; world = {maxx-minx}x{maxy-miny} blocks = {W}x{H}px")
+
+canvas = Image.new('RGB',(W,H),(20,20,30))
+for c in sorted(placed, key=lambda c: (pos[c][1],pos[c][0])):
+    x = (pos[c][0]-minx)*32; y = (pos[c][1]-miny)*32
+    canvas.paste(render_map(c), (x,y))
+
+out = sys.argv[1] if len(sys.argv)>1 else '/tmp/kanto_overworld.png'
+canvas.save(out)
+# also a downscaled preview for quick viewing
+scale = max(1, max(W,H)//1600 + 1)
+canvas.resize((W//scale, H//scale)).save(out.replace('.png','_preview.png'))
+print(f"saved {out} ({W}x{H})  + preview /{scale}x")
-- 
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