57 lines
1.4 KiB
JavaScript
57 lines
1.4 KiB
JavaScript
import constant from "./constant.js";
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export default function(radius, x, y) {
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var nodes,
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strength = constant(0.1),
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strengths,
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radiuses;
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if (typeof radius !== "function") radius = constant(+radius);
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if (x == null) x = 0;
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if (y == null) y = 0;
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function force(alpha) {
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for (var i = 0, n = nodes.length; i < n; ++i) {
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var node = nodes[i],
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dx = node.x - x || 1e-6,
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dy = node.y - y || 1e-6,
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r = Math.sqrt(dx * dx + dy * dy),
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k = (radiuses[i] - r) * strengths[i] * alpha / r;
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node.vx += dx * k;
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node.vy += dy * k;
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}
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}
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function initialize() {
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if (!nodes) return;
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var i, n = nodes.length;
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strengths = new Array(n);
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radiuses = new Array(n);
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for (i = 0; i < n; ++i) {
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radiuses[i] = +radius(nodes[i], i, nodes);
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strengths[i] = isNaN(radiuses[i]) ? 0 : +strength(nodes[i], i, nodes);
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}
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}
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force.initialize = function(_) {
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nodes = _, initialize();
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};
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force.strength = function(_) {
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return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), initialize(), force) : strength;
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};
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force.radius = function(_) {
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return arguments.length ? (radius = typeof _ === "function" ? _ : constant(+_), initialize(), force) : radius;
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};
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force.x = function(_) {
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return arguments.length ? (x = +_, force) : x;
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};
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force.y = function(_) {
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return arguments.length ? (y = +_, force) : y;
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};
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return force;
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}
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