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import Quad from "./quad.js";
export default function(x, y, radius) {
var data,
x0 = this._x0,
y0 = this._y0,
x1,
y1,
x2,
y2,
x3 = this._x1,
y3 = this._y1,
quads = [],
node = this._root,
q,
i;
if (node) quads.push(new Quad(node, x0, y0, x3, y3));
if (radius == null) radius = Infinity;
else {
x0 = x - radius, y0 = y - radius;
x3 = x + radius, y3 = y + radius;
radius *= radius;
}
while (q = quads.pop()) {
// Stop searching if this quadrant can’t contain a closer node.
if (!(node = q.node)
|| (x1 = q.x0) > x3
|| (y1 = q.y0) > y3
|| (x2 = q.x1) < x0
|| (y2 = q.y1) < y0) continue;
// Bisect the current quadrant.
if (node.length) {
var xm = (x1 + x2) / 2,
ym = (y1 + y2) / 2;
quads.push(
new Quad(node[3], xm, ym, x2, y2),
new Quad(node[2], x1, ym, xm, y2),
new Quad(node[1], xm, y1, x2, ym),
new Quad(node[0], x1, y1, xm, ym)
);
// Visit the closest quadrant first.
if (i = (y >= ym) << 1 | (x >= xm)) {
q = quads[quads.length - 1];
quads[quads.length - 1] = quads[quads.length - 1 - i];
quads[quads.length - 1 - i] = q;
}
}
// Visit this point. (Visiting coincident points isn’t necessary!)
else {
var dx = x - +this._x.call(null, node.data),
dy = y - +this._y.call(null, node.data),
d2 = dx * dx + dy * dy;
if (d2 < radius) {
var d = Math.sqrt(radius = d2);
x0 = x - d, y0 = y - d;
x3 = x + d, y3 = y + d;
data = node.data;
}
}
}
return data;
}
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