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428 lines
13 KiB
428 lines
13 KiB
/**
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* Created by Alex on 2/23/2015.
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*/
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import {BarnesHutSolver} from "./components/physics/BarnesHutSolver";
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import {Repulsion} from "./components/physics/RepulsionSolver";
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import {HierarchicalRepulsion} from "./components/physics/HierarchicalRepulsionSolver";
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import {SpringSolver} from "./components/physics/SpringSolver";
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import {HierarchicalSpringSolver} from "./components/physics/HierarchicalSpringSolver";
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import {CentralGravitySolver} from "./components/physics/CentralGravitySolver";
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var util = require('../../util');
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class PhysicsEngine {
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constructor(body) {
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this.body = body;
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this.physicsBody = {calculationNodes: {}, calculationNodeIndices:[], forces: {}, velocities: {}};
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this.simulationInterval = 1000 / 60;
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this.requiresTimeout = true;
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this.previousStates = {};
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this.renderTimer == undefined;
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this.stabilized = false;
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this.stabilizationIterations = 0;
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// default options
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this.options = {};
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this.defaultOptions = {
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barnesHut: {
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thetaInverted: 1 / 0.5, // inverted to save time during calculation
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gravitationalConstant: -2000,
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centralGravity: 0.3,
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springLength: 95,
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springConstant: 0.04,
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damping: 0.09
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},
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repulsion: {
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centralGravity: 0.0,
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springLength: 200,
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springConstant: 0.05,
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nodeDistance: 100,
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damping: 0.09
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},
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hierarchicalRepulsion: {
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centralGravity: 0.0,
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springLength: 100,
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springConstant: 0.01,
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nodeDistance: 150,
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damping: 0.09
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},
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model: 'BarnesHut',
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timestep: 0.5,
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maxVelocity: 50,
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minVelocity: 0.1, // px/s
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stabilization: {
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enabled: true,
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iterations: 1000, // maximum number of iteration to stabilize
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updateInterval: 100,
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onlyDynamicEdges: false,
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zoomExtent: true
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}
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}
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util.extend(this.options, this.defaultOptions);
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this.body.emitter.on("stabilize", () => {this.startSimulation();});
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this.body.emitter.on("startSimulation", () => {this.stabilized = false; this.runSimulation();});
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this.body.emitter.on("stopSimulation", () => {this.stopSimulation();});
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}
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setOptions(options) {
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if (options !== undefined) {
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if (typeof options.stabilization == 'boolean') {
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options.stabilization = {
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enabled: options.stabilization
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}
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}
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util.deepExtend(this.options, options);
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}
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this.init();
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}
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init() {
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var options;
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if (this.options.model == "repulsion") {
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options = this.options.repulsion;
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this.nodesSolver = new Repulsion(this.body, this.physicsBody, options);
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this.edgesSolver = new SpringSolver(this.body, this.physicsBody, options);
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}
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else if (this.options.model == "hierarchicalRepulsion") {
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options = this.options.hierarchicalRepulsion;
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this.nodesSolver = new HierarchicalRepulsion(this.body, this.physicsBody, options);
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this.edgesSolver = new HierarchicalSpringSolver(this.body, this.physicsBody, options);
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}
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else { // barnesHut
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options = this.options.barnesHut;
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this.nodesSolver = new BarnesHutSolver(this.body, this.physicsBody, options);
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this.edgesSolver = new SpringSolver(this.body, this.physicsBody, options);
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}
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this.gravitySolver = new CentralGravitySolver(this.body, this.physicsBody, options);
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this.modelOptions = options;
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}
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startSimulation() {
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this.stabilized = false;
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if (this.options.stabilization.enabled === true) {
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this.stabilize();
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}
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else {
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this.runSimulation();
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}
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}
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stopSimulation() {
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this.stabilized = true;
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if (this.viewFunction !== undefined) {
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this.body.emitter.off("_beforeRender", this.viewFunction);
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this.viewFunction = undefined;
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this.body.emitter.emit("_stopRendering");
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}
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}
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runSimulation() {
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if (this.viewFunction === undefined) {
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this.viewFunction = this.simulationStep.bind(this);
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this.body.emitter.on("_beforeRender", this.viewFunction);
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this.body.emitter.emit("_startRendering");
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}
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}
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simulationStep() {
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// check if the physics have settled
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var startTime = Date.now();
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this.physicsTick();
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var physicsTime = Date.now() - startTime;
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// run double speed if it is a little graph
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if ((physicsTime < 0.4 * this.simulationInterval || this.runDoubleSpeed == true) && this.stabilized === false) {
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this.physicsTick();
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// this makes sure there is no jitter. The decision is taken once to run it at double speed.
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this.runDoubleSpeed = true;
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}
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if (this.stabilized === true) {
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if (this.stabilizationIterations > 1) {
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// trigger the "stabilized" event.
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// The event is triggered on the next tick, to prevent the case that
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// it is fired while initializing the Network, in which case you would not
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// be able to catch it
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var me = this;
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var params = {
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iterations: this.stabilizationIterations
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};
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this.stabilizationIterations = 0;
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this.startedStabilization = false;
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setTimeout(function () {
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me.body.emitter.emit("stabilized", params);
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}, 0);
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}
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else {
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this.stabilizationIterations = 0;
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}
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this.stopSimulation();
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}
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}
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/**
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* A single simulation step (or "tick") in the physics simulation
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*
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* @private
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*/
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physicsTick() {
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if (this.stabilized === false) {
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this.calculateForces();
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this.stabilized = this.moveNodes();
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// determine if the network has stabilzied
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if (this.stabilized === true) {
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this.revert();
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}
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else {
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// this is here to ensure that there is no start event when the network is already stable.
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if (this.startedStabilization == false) {
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this.body.emitter.emit("startStabilizing");
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this.startedStabilization = true;
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}
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}
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this.stabilizationIterations++;
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}
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}
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/**
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* Smooth curves are created by adding invisible nodes in the center of the edges. These nodes are also
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* handled in the calculateForces function. We then use a quadratic curve with the center node as control.
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* This function joins the datanodes and invisible (called support) nodes into one object.
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* We do this so we do not contaminate this.body.nodes with the support nodes.
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*
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* @private
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*/
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_updateCalculationNodes() {
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this.physicsBody.calculationNodes = {};
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this.physicsBody.forces = {};
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this.physicsBody.calculationNodeIndices = [];
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for (let i = 0; i < this.body.nodeIndices.length; i++) {
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let nodeId = this.body.nodeIndices[i];
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this.physicsBody.calculationNodes[nodeId] = this.body.nodes[nodeId];
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}
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// if support nodes are used, we have them here
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var supportNodes = this.body.supportNodes;
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for (let i = 0; i < this.body.supportNodeIndices.length; i++) {
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let supportNodeId = this.body.supportNodeIndices[i];
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if (this.body.edges[supportNodes[supportNodeId].parentEdgeId] !== undefined) {
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this.physicsBody.calculationNodes[supportNodeId] = supportNodes[supportNodeId];
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}
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else {
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console.error("Support node detected that does not have an edge!")
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}
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}
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this.physicsBody.calculationNodeIndices = Object.keys(this.physicsBody.calculationNodes);
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for (let i = 0; i < this.physicsBody.calculationNodeIndices.length; i++) {
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let nodeId = this.physicsBody.calculationNodeIndices[i];
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this.physicsBody.forces[nodeId] = {x:0,y:0};
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// forces can be reset because they are recalculated. Velocities have to persist.
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if (this.physicsBody.velocities[nodeId] === undefined) {
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this.physicsBody.velocities[nodeId] = {x:0,y:0};
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}
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}
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// clean deleted nodes from the velocity vector
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for (let nodeId in this.physicsBody.velocities) {
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if (this.physicsBody.calculationNodes[nodeId] === undefined) {
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delete this.physicsBody.velocities[nodeId];
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}
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}
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}
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revert() {
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var nodeIds = Object.keys(this.previousStates);
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var nodes = this.physicsBody.calculationNodes;
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var velocities = this.physicsBody.velocities;
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for (let i = 0; i < nodeIds.length; i++) {
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let nodeId = nodeIds[i];
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if (nodes[nodeId] !== undefined) {
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velocities[nodeId].x = this.previousStates[nodeId].vx;
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velocities[nodeId].y = this.previousStates[nodeId].vy;
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nodes[nodeId].x = this.previousStates[nodeId].x;
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nodes[nodeId].y = this.previousStates[nodeId].y;
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}
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else {
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delete this.previousStates[nodeId];
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}
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}
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}
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moveNodes() {
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var nodesPresent = false;
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var nodeIndices = this.physicsBody.calculationNodeIndices;
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var maxVelocity = this.options.maxVelocity === 0 ? 1e9 : this.options.maxVelocity;
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var stabilized = true;
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var vminCorrected = this.options.minVelocity / Math.max(this.body.view.scale,0.05);
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for (let i = 0; i < nodeIndices.length; i++) {
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let nodeId = nodeIndices[i];
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let nodeVelocity = this._performStep(nodeId, maxVelocity);
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// stabilized is true if stabilized is true and velocity is smaller than vmin --> all nodes must be stabilized
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stabilized = nodeVelocity < vminCorrected && stabilized === true;
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nodesPresent = true;
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}
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if (nodesPresent == true) {
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if (vminCorrected > 0.5*this.options.maxVelocity) {
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return false;
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}
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else {
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return stabilized;
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}
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}
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return true;
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}
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_performStep(nodeId,maxVelocity) {
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var node = this.physicsBody.calculationNodes[nodeId];
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var timestep = this.options.timestep;
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var forces = this.physicsBody.forces;
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var velocities = this.physicsBody.velocities;
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// store the state so we can revert
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this.previousStates[nodeId] = {x:node.x, y:node.y, vx:velocities[nodeId].x, vy:velocities[nodeId].y};
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if (!node.xFixed) {
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let dx = this.modelOptions.damping * velocities[nodeId].x; // damping force
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let ax = (forces[nodeId].x - dx) / node.options.mass; // acceleration
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velocities[nodeId].x += ax * timestep; // velocity
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velocities[nodeId].x = (Math.abs(velocities[nodeId].x) > maxVelocity) ? ((velocities[nodeId].x > 0) ? maxVelocity : -maxVelocity) : velocities[nodeId].x;
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node.x += velocities[nodeId].x * timestep; // position
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}
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else {
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forces[nodeId].x = 0;
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velocities[nodeId].x = 0;
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}
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if (!node.yFixed) {
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let dy = this.modelOptions.damping * velocities[nodeId].y; // damping force
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let ay = (forces[nodeId].y - dy) / node.options.mass; // acceleration
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velocities[nodeId].y += ay * timestep; // velocity
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velocities[nodeId].y = (Math.abs(velocities[nodeId].y) > maxVelocity) ? ((velocities[nodeId].y > 0) ? maxVelocity : -maxVelocity) : velocities[nodeId].y;
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node.y += velocities[nodeId].y * timestep; // position
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}
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else {
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forces[nodeId].y = 0;
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velocities[nodeId].y = 0;
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}
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var totalVelocity = Math.sqrt(Math.pow(velocities[nodeId].x,2) + Math.pow(velocities[nodeId].y,2));
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return totalVelocity;
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}
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calculateForces() {
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this.gravitySolver.solve();
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this.nodesSolver.solve();
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this.edgesSolver.solve();
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}
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/**
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* When initializing and stabilizing, we can freeze nodes with a predefined position. This greatly speeds up stabilization
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* because only the supportnodes for the smoothCurves have to settle.
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*
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* @private
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*/
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_freezeNodes() {
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var nodes = this.body.nodes;
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for (var id in nodes) {
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if (nodes.hasOwnProperty(id)) {
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if (nodes[id].x != null && nodes[id].y != null) {
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nodes[id].fixedData.x = nodes[id].xFixed;
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nodes[id].fixedData.y = nodes[id].yFixed;
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nodes[id].xFixed = true;
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nodes[id].yFixed = true;
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}
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}
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}
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}
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/**
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* Unfreezes the nodes that have been frozen by _freezeDefinedNodes.
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*
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* @private
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*/
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_restoreFrozenNodes() {
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var nodes = this.body.nodes;
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for (var id in nodes) {
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if (nodes.hasOwnProperty(id)) {
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if (nodes[id].fixedData.x != null) {
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nodes[id].xFixed = nodes[id].fixedData.x;
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nodes[id].yFixed = nodes[id].fixedData.y;
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}
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}
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}
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}
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/**
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* Find a stable position for all nodes
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* @private
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*/
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stabilize() {
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if (this.options.stabilization.onlyDynamicEdges == true) {
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this._freezeNodes();
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}
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this.stabilizationSteps = 0;
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setTimeout(this._stabilizationBatch.bind(this),0);
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}
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_stabilizationBatch() {
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var count = 0;
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while (this.stabilized == false && count < this.options.stabilization.updateInterval && this.stabilizationSteps < this.options.stabilization.iterations) {
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this.physicsTick();
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this.stabilizationSteps++;
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count++;
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}
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if (this.stabilized == false && this.stabilizationSteps < this.options.stabilization.iterations) {
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this.body.emitter.emit("stabilizationProgress", {steps: this.stabilizationSteps, total: this.options.stabilization.iterations});
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setTimeout(this._stabilizationBatch.bind(this),0);
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}
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else {
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this._finalizeStabilization();
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}
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}
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_finalizeStabilization() {
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if (this.options.stabilization.zoomExtent == true) {
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this.body.emitter.emit("zoomExtent", {duration:0});
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}
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if (this.options.stabilization.onlyDynamicEdges == true) {
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this._restoreFrozenNodes();
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}
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this.body.emitter.emit("stabilizationIterationsDone");
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this.body.emitter.emit("_requestRedraw");
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}
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}
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export {PhysicsEngine};
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