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42 lines
1.0 KiB
42 lines
1.0 KiB
1 year ago
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import constant from "./constant";
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export default function(x) {
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var strength = constant(0.1),
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nodes,
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strengths,
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xz;
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if (typeof x !== "function") x = constant(x == null ? 0 : +x);
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function force(alpha) {
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for (var i = 0, n = nodes.length, node; i < n; ++i) {
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node = nodes[i], node.vx += (xz[i] - node.x) * strengths[i] * alpha;
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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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xz = new Array(n);
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for (i = 0; i < n; ++i) {
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strengths[i] = isNaN(xz[i] = +x(nodes[i], i, nodes)) ? 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 = _;
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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.x = function(_) {
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return arguments.length ? (x = typeof _ === "function" ? _ : constant(+_), initialize(), force) : x;
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};
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return force;
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}
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