71 lines
1.7 KiB
JavaScript
71 lines
1.7 KiB
JavaScript
|
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;
|
|||
|
|
}
|