import pathlib,json,urllib.request,hashlib,concurrent.futures
root=pathlib.Path.cwd(); folder=root/'assets/textures/quarry_realism'; folder.mkdir(parents=True,exist_ok=True)
assets={'aerial_asphalt_01':2.0,'concrete_wall_007':3.0,'rusty_metal_02':2.0}
def task(pair):
 a,meters=pair
 try: meta=json.load(urllib.request.urlopen(urllib.request.Request('https://api.polyhaven.com/files/'+a,headers={'User-Agent':'BLOCKLINE asset preparation'}),timeout=60))
 except Exception as e: print(a,e,flush=True); return
 dest=folder/a; dest.mkdir(exist_ok=True); manifest={}
 for kind in ['Diffuse','nor_gl','Rough','Metal']:
  if kind not in meta: continue
  info=meta[kind]['4k']['jpg']; p=dest/(kind+'.jpg')
  if not p.exists(): p.write_bytes(urllib.request.urlopen(info['url'],timeout=120).read())
  assert hashlib.md5(p.read_bytes()).hexdigest()==info['md5'];manifest[kind]=info
 (dest/'source.json').write_text(json.dumps({'source':'https://polyhaven.com/a/'+a,'license':'CC0-1.0','meters':meters,'files':manifest},indent=2))
 print(a,'OK',flush=True)
with concurrent.futures.ThreadPoolExecutor(max_workers=3) as ex:list(ex.map(task,assets.items()))