78 lines
2.1 KiB
JavaScript
78 lines
2.1 KiB
JavaScript
import constant from "./constant";
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import jiggle from "./jiggle";
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/**
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* Modified link force algorithm
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* - simplify calculations for parameters locked for spring model
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* - removed other unused functions
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* Alpha should be constant 1 for accurate simulation
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*/
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export default function(links) {
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var dataSizeFactor,
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distance = constant(30),
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distances = [],
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nodes,
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iterations = 1;
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if (links == null) links = [];
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function force(alpha) {
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// Each iteration in a tick
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for (var k = 0, n = nodes.length, source, target, i, j, x, y, l; k < iterations; ++k) {
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// For each link
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for (i = 1; i < n; i++) for (j = 0; j < i; j++) {
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// jiggle so it wont divide / multiply by zero after this
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source = nodes[i];
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target = nodes[j];
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x = target.x + target.vx - source.x - source.vx || jiggle();
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y = target.y + target.vy - source.y - source.vy || jiggle();
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l = Math.sqrt(x * x + y * y);
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l = (l - distances[i*(i-1)/2+j]) / l * dataSizeFactor * alpha;
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x *= l, y *= l;
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target.vx -= x;
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target.vy -= y;
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source.vx += x;
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source.vy += y;
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}
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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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dataSizeFactor = 0.5/(nodes.length-1);
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initializeDistance();
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}
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function initializeDistance() {
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if (!nodes) return;
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for (let i = 1, n = nodes.length; i < n; i++) {
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for (let j = 0; j < i; j++) {
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distances.push(distanceFunction(nodes[i], nodes[j], props, norm));
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}
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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.links = function(_) {
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return arguments.length ? (links = _, initialize(), force) : links;
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};
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force.id = function(_) {
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return arguments.length ? (id = _, force) : id;
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};
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force.iterations = function(_) {
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return arguments.length ? (iterations = +_, force) : iterations;
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};
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force.distance = function(_) {
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return arguments.length ? (distance = typeof _ === "function" ? _ : constant(+_), initializeDistance(), force) : distance;
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};
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return force;
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}
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