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import {dispatch} from "d3-dispatch";
import {timer} from "d3-timer";
import lcg from "./lcg.js";
export function x(d) {
return d.x;
}
export function y(d) {
return d.y;
}
var initialRadius = 10,
initialAngle = Math.PI * (3 - Math.sqrt(5));
export default function(nodes) {
var simulation,
alpha = 1,
alphaMin = 0.001,
alphaDecay = 1 - Math.pow(alphaMin, 1 / 300),
alphaTarget = 0,
velocityDecay = 0.6,
forces = new Map(),
stepper = timer(step),
event = dispatch("tick", "end"),
random = lcg();
if (nodes == null) nodes = [];
function step() {
tick();
event.call("tick", simulation);
if (alpha < alphaMin) {
stepper.stop();
event.call("end", simulation);
}
}
function tick(iterations) {
var i, n = nodes.length, node;
if (iterations === undefined) iterations = 1;
for (var k = 0; k < iterations; ++k) {
alpha += (alphaTarget - alpha) * alphaDecay;
forces.forEach(function(force) {
force(alpha);
});
for (i = 0; i < n; ++i) {
node = nodes[i];
if (node.fx == null) node.x += node.vx *= velocityDecay;
else node.x = node.fx, node.vx = 0;
if (node.fy == null) node.y += node.vy *= velocityDecay;
else node.y = node.fy, node.vy = 0;
}
}
return simulation;
}
function initializeNodes() {
for (var i = 0, n = nodes.length, node; i < n; ++i) {
node = nodes[i], node.index = i;
if (node.fx != null) node.x = node.fx;
if (node.fy != null) node.y = node.fy;
if (isNaN(node.x) || isNaN(node.y)) {
var radius = initialRadius * Math.sqrt(0.5 + i), angle = i * initialAngle;
node.x = radius * Math.cos(angle);
node.y = radius * Math.sin(angle);
}
if (isNaN(node.vx) || isNaN(node.vy)) {
node.vx = node.vy = 0;
}
}
}
function initializeForce(force) {
if (force.initialize) force.initialize(nodes, random);
return force;
}
initializeNodes();
return simulation = {
tick: tick,
restart: function() {
return stepper.restart(step), simulation;
},
stop: function() {
return stepper.stop(), simulation;
},
nodes: function(_) {
return arguments.length ? (nodes = _, initializeNodes(), forces.forEach(initializeForce), simulation) : nodes;
},
alpha: function(_) {
return arguments.length ? (alpha = +_, simulation) : alpha;
},
alphaMin: function(_) {
return arguments.length ? (alphaMin = +_, simulation) : alphaMin;
},
alphaDecay: function(_) {
return arguments.length ? (alphaDecay = +_, simulation) : +alphaDecay;
},
alphaTarget: function(_) {
return arguments.length ? (alphaTarget = +_, simulation) : alphaTarget;
},
velocityDecay: function(_) {
return arguments.length ? (velocityDecay = 1 - _, simulation) : 1 - velocityDecay;
},
randomSource: function(_) {
return arguments.length ? (random = _, forces.forEach(initializeForce), simulation) : random;
},
force: function(name, _) {
return arguments.length > 1 ? ((_ == null ? forces.delete(name) : forces.set(name, initializeForce(_))), simulation) : forces.get(name);
},
find: function(x, y, radius) {
var i = 0,
n = nodes.length,
dx,
dy,
d2,
node,
closest;
if (radius == null) radius = Infinity;
else radius *= radius;
for (i = 0; i < n; ++i) {
node = nodes[i];
dx = x - node.x;
dy = y - node.y;
d2 = dx * dx + dy * dy;
if (d2 < radius) closest = node, radius = d2;
}
return closest;
},
on: function(name, _) {
return arguments.length > 1 ? (event.on(name, _), simulation) : event.on(name);
}
};
}