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import {quadtree} from "d3-quadtree";
import constant from "./constant.js";
import jiggle from "./jiggle.js";
function x(d) {
return d.x + d.vx;
}
function y(d) {
return d.y + d.vy;
}
export default function(radius) {
var nodes,
radii,
random,
strength = 1,
iterations = 1;
if (typeof radius !== "function") radius = constant(radius == null ? 1 : +radius);
function force() {
var i, n = nodes.length,
tree,
node,
xi,
yi,
ri,
ri2;
for (var k = 0; k < iterations; ++k) {
tree = quadtree(nodes, x, y).visitAfter(prepare);
for (i = 0; i < n; ++i) {
node = nodes[i];
ri = radii[node.index], ri2 = ri * ri;
xi = node.x + node.vx;
yi = node.y + node.vy;
tree.visit(apply);
}
}
function apply(quad, x0, y0, x1, y1) {
var data = quad.data, rj = quad.r, r = ri + rj;
if (data) {
if (data.index > node.index) {
var x = xi - data.x - data.vx,
y = yi - data.y - data.vy,
l = x * x + y * y;
if (l < r * r) {
if (x === 0) x = jiggle(random), l += x * x;
if (y === 0) y = jiggle(random), l += y * y;
l = (r - (l = Math.sqrt(l))) / l * strength;
node.vx += (x *= l) * (r = (rj *= rj) / (ri2 + rj));
node.vy += (y *= l) * r;
data.vx -= x * (r = 1 - r);
data.vy -= y * r;
}
}
return;
}
return x0 > xi + r || x1 < xi - r || y0 > yi + r || y1 < yi - r;
}
}
function prepare(quad) {
if (quad.data) return quad.r = radii[quad.data.index];
for (var i = quad.r = 0; i < 4; ++i) {
if (quad[i] && quad[i].r > quad.r) {
quad.r = quad[i].r;
}
}
}
function initialize() {
if (!nodes) return;
var i, n = nodes.length, node;
radii = new Array(n);
for (i = 0; i < n; ++i) node = nodes[i], radii[node.index] = +radius(node, i, nodes);
}
force.initialize = function(_nodes, _random) {
nodes = _nodes;
random = _random;
initialize();
};
force.iterations = function(_) {
return arguments.length ? (iterations = +_, force) : iterations;
};
force.strength = function(_) {
return arguments.length ? (strength = +_, force) : strength;
};
force.radius = function(_) {
return arguments.length ? (radius = typeof _ === "function" ? _ : constant(+_), initialize(), force) : radius;
};
return force;
}
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