Claude
6aac03f112
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HJhXuLD2Z6hv3Wqeq9UL9K
134 lines
4.1 KiB
Python
134 lines
4.1 KiB
Python
"""Line of sight: visibility polygon from a point around wall segments, and cutting the map image to it.
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The server cuts the image, so a player's browser only ever receives the pixels their character can see (no peeking through
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dev tools). Pure Python on purpose (no numpy): a few hundred wall segments are fast enough, and results are cached."""
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import io
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import math
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from collections import OrderedDict
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from PIL import Image, ImageDraw
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EPS = 1e-5
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def polygon(origin, segs, w, h, radius=0.0):
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"""Points of the area visible from origin. segs: [(x1, y1, x2, y2)] that block sight; radius 0 means unlimited."""
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ox, oy = origin
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border = [(0, 0, w, 0), (w, 0, w, h), (w, h, 0, h), (0, h, 0, 0)]
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if radius:
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r2 = (radius + 1) ** 2
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def near(s):
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x1, y1, x2, y2 = s
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dx, dy = x2 - x1, y2 - y1
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L = dx * dx + dy * dy
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t = 0 if L == 0 else max(0, min(1, ((ox - x1) * dx + (oy - y1) * dy) / L))
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return (x1 + t * dx - ox) ** 2 + (y1 + t * dy - oy) ** 2 <= r2
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segs = [s for s in segs if near(s)]
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allsegs = segs + border
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angles = []
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for x1, y1, x2, y2 in allsegs:
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for x, y in ((x1, y1), (x2, y2)):
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if radius and (x - ox) ** 2 + (y - oy) ** 2 > (radius * 3) ** 2:
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continue
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a = math.atan2(y - oy, x - ox)
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angles += (a - EPS, a, a + EPS)
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if radius:
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angles += [i * (2 * math.pi / 120) for i in range(120)]
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angles.sort()
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pts = []
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for a in angles:
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dx, dy = math.cos(a), math.sin(a)
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best = radius if radius else float("inf")
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for x1, y1, x2, y2 in allsegs:
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ex, ey = x2 - x1, y2 - y1
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den = dx * ey - dy * ex
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if abs(den) < 1e-12:
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continue
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px, py = x1 - ox, y1 - oy
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t = (px * ey - py * ex) / den
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if t < 0 or t >= best:
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continue
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u = (px * dy - py * dx) / den
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if -1e-9 <= u <= 1 + 1e-9:
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best = t
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if best == float("inf"):
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continue
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pts.append((ox + dx * best, oy + dy * best))
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return pts
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def inside(pt, poly) -> bool:
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x, y = pt
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c = False
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j = len(poly) - 1
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for i in range(len(poly)):
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xi, yi = poly[i]
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xj, yj = poly[j]
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if (yi > y) != (yj > y) and x < (xj - xi) * (y - yi) / (yj - yi) + xi:
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c = not c
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j = i
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return c
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class Lru(OrderedDict):
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def __init__(self, size):
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super().__init__()
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self.size = size
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def put(self, k, v):
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self[k] = v
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self.move_to_end(k)
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while len(self) > self.size:
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self.popitem(last=False)
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def fetch(self, k):
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if k in self:
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self.move_to_end(k)
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return self[k]
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_images = Lru(2)
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_polys = Lru(128)
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_cuts = Lru(24)
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fog_cache = Lru(12)
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def cached_polygon(key, make):
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v = _polys.fetch(key)
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if v is None:
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v = make()
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_polys.put(key, v)
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return v
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def source(path):
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key = (str(path), path.stat().st_mtime_ns)
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im = _images.fetch(key)
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if im is None:
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im = Image.open(path)
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im.load()
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im = im.convert("RGB")
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_images.put(key, im)
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return im
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def cut(path, poly, key):
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"""The part of the image inside the polygon (everything else black), cropped to its bounding box.
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Returns (webp bytes, (x, y, w, h))."""
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hit = _cuts.fetch(key)
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if hit:
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return hit
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im = source(path)
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xs, ys = [p[0] for p in poly], [p[1] for p in poly]
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x0, y0 = max(0, int(math.floor(min(xs)))), max(0, int(math.floor(min(ys))))
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x1, y1 = min(im.width, int(math.ceil(max(xs)))), min(im.height, int(math.ceil(max(ys))))
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w, h = max(1, x1 - x0), max(1, y1 - y0)
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mask = Image.new("L", (w, h), 0)
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ImageDraw.Draw(mask).polygon([(x - x0, y - y0) for x, y in poly], fill=255)
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piece = Image.composite(im.crop((x0, y0, x0 + w, y0 + h)), Image.new("RGB", (w, h), (0, 0, 0)), mask)
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out = io.BytesIO()
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piece.save(out, "WEBP", quality=82, method=1)
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res = (out.getvalue(), (x0, y0, w, h))
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_cuts.put(key, res)
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return res
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