Numpy computing 2D SDF function of a polygon

polygon2sdf.py

import numpy as np

def compute_sdf_polygon(vertices, points):
    vertices = vertices[:, None, ...]
    points = points[None, :, ...]
    d = np.sum((points[0] - vertices[0]) * (points[0] - vertices[0]), -1)
    vert_offset = np.concatenate([vertices[-1:], vertices[:-1]], 0)
    e = vert_offset - vertices
    w = points - vertices
    b = w - e * np.clip(np.sum(w * e, -1) / np.sum(e * e, -1), 0., 1.)[..., None]
    b_dot = np.sum(b * b, -1)
    d = np.minimum(d, np.min(b_dot, 0))
    c = np.stack([
        points[..., 1] > vertices[..., 1],
        points[..., 1] <= vert_offset[..., 1],
        e[..., 0] * w[..., 1] > e[...,1] * w[...,0]], -1)
    s = np.where(np.logical_or(np.all(c, -1), np.all(np.logical_not(c), -1)), -1, 1)
    s = np.prod(s, 0)
    return s * np.sqrt(d)