116 lines
2.6 KiB
JavaScript
116 lines
2.6 KiB
JavaScript
import {dispatch} from "d3-dispatch";
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import {map} from "d3-collection";
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import {timer} from "d3-timer";
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import {pi} from "./math";
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export function x(d) {
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return d.x;
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}
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export function y(d) {
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return d.y;
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}
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var initialRadius = 10,
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initialAngle = pi * (3 - Math.sqrt(5));
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export default function(nodes) {
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var simulation,
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iteration = 0,
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alphaMin = 0.001,
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alphaDecay = -0.02,
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drag = 0.6,
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forces = map(),
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stepper = timer(step),
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event = dispatch("tick", "end");
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if (nodes == null) nodes = [];
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function restart() {
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iteration = 0;
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stepper.restart(step);
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return simulation;
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}
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function stop() {
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stepper.stop();
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return simulation;
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}
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function step() {
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var stop = tick();
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event.call("tick", simulation);
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if (stop) {
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stepper.stop();
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event.call("end", simulation);
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}
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}
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function tick() {
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var alpha = Math.exp(++iteration * alphaDecay);
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forces.each(function(force) {
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force(alpha);
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});
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for (var i = 0, n = nodes.length, node; i < n; ++i) {
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node = nodes[i];
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node.x += node.vx *= drag;
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node.y += node.vy *= drag;
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}
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return alpha < alphaMin;
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}
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function initializeNodes() {
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for (var i = 0, n = nodes.length, node; i < n; ++i) {
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node = nodes[i], node.index = i;
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if (isNaN(node.x) || isNaN(node.y)) {
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var radius = initialRadius * Math.sqrt(i), angle = i * initialAngle;
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node.x = radius * Math.cos(angle);
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node.y = radius * Math.sin(angle);
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}
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if (isNaN(node.vx) || isNaN(node.vy)) {
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node.vx = node.vy = 0;
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}
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}
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}
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function initializeForce(force) {
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if (force.initialize) force.initialize(nodes);
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return force;
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}
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initializeNodes();
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return simulation = {
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restart: restart,
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stop: stop,
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tick: tick,
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nodes: function(_) {
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return arguments.length ? (nodes = _, initializeNodes(), forces.each(initializeForce), simulation) : nodes;
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},
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alphaMin: function(_) {
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return arguments.length ? (alphaMin = _, simulation) : alphaMin;
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},
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alphaDecay: function(_) {
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return arguments.length ? (iteration = +_ ? Math.round(iteration * alphaDecay / -_) : 0, alphaDecay = -_, simulation) : -alphaDecay;
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},
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drag: function(_) {
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return arguments.length ? (drag = 1 - _, simulation) : 1 - drag;
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},
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force: function(name, _) {
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return arguments.length > 1 ? ((_ == null ? forces.remove(name) : forces.set(name, initializeForce(_))), simulation) : forces.get(name);
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},
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on: function(name, _) {
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return arguments.length > 1 ? (event.on(name, _), simulation) : event.on(name);
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}
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};
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}
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