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245 lines
7.2 KiB
245 lines
7.2 KiB
/**
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* Created by Alex on 2/6/14.
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*/
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var physicsMixin = {
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/**
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* Toggling barnes Hut calculation on and off.
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*
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* @private
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*/
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_toggleBarnesHut : function() {
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this.constants.physics.barnesHut.enabled = !this.constants.physics.barnesHut.enabled;
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this._loadSelectedForceSolver();
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this.moving = true;
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this.start();
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},
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/**
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* Before calculating the forces, we check if we need to cluster to keep up performance and we check
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* if there is more than one node. If it is just one node, we dont calculate anything.
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*
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* @private
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*/
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_initializeForceCalculation : function() {
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// stop calculation if there is only one node
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if (this.nodeIndices.length == 1) {
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this.nodes[this.nodeIndices[0]]._setForce(0,0);
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}
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else {
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// if there are too many nodes on screen, we cluster without repositioning
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if (this.nodeIndices.length > this.constants.clustering.clusterThreshold && this.constants.clustering.enabled == true) {
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this.clusterToFit(this.constants.clustering.reduceToNodes, false);
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}
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// we now start the force calculation
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this._calculateForces();
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}
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},
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/**
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* Calculate the external forces acting on the nodes
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* Forces are caused by: edges, repulsing forces between nodes, gravity
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* @private
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*/
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_calculateForces : function() {
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// Gravity is required to keep separated groups from floating off
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// the forces are reset to zero in this loop by using _setForce instead
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// of _addForce
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this._calculateGravitationalForces();
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this._calculateNodeForces();
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if (this.constants.smoothCurves == true) {
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this._calculateSpringForcesWithSupport();
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}
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else {
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this._calculateSpringForces();
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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.nodes with the support nodes.
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*
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* @private
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*/
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_updateCalculationNodes : function() {
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if (this.constants.smoothCurves == true) {
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this.calculationNodes = {};
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this.calculationNodeIndices = [];
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for (var nodeId in this.nodes) {
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if (this.nodes.hasOwnProperty(nodeId)) {
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this.calculationNodes[nodeId] = this.nodes[nodeId];
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}
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}
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var supportNodes = this.sectors['support']['nodes'];
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for (var supportNodeId in supportNodes) {
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if (supportNodes.hasOwnProperty(supportNodeId)) {
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if (this.edges.hasOwnProperty(supportNodes[supportNodeId].parentEdgeId)) {
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this.calculationNodes[supportNodeId] = supportNodes[supportNodeId];
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}
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else {
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supportNodes[supportNodeId]._setForce(0,0);
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}
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}
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}
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for (var idx in this.calculationNodes) {
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if (this.calculationNodes.hasOwnProperty(idx)) {
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this.calculationNodeIndices.push(idx);
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}
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}
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}
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else {
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this.calculationNodes = this.nodes;
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this.calculationNodeIndices = this.nodeIndices;
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}
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},
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/**
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* this function applies the central gravity effect to keep groups from floating off
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*
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* @private
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*/
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_calculateGravitationalForces : function() {
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var dx, dy, distance, node, i;
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var nodes = this.calculationNodes;
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var gravity = this.constants.physics.centralGravity;
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var gravityForce = 0;
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for (i = 0; i < this.calculationNodeIndices.length; i++) {
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node = nodes[this.calculationNodeIndices[i]];
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node.damping = this.constants.physics.damping; // possibly add function to alter damping properties of clusters.
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// gravity does not apply when we are in a pocket sector
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if (this._sector() == "default") {
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dx = -node.x;
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dy = -node.y;
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distance = Math.sqrt(dx*dx + dy*dy);
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gravityForce = gravity / distance;
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node.fx = dx * gravityForce;
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node.fy = dy * gravityForce;
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}
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else {
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node.fx = 0;
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node.fy = 0;
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}
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}
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},
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/**
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* this function calculates the effects of the springs in the case of unsmooth curves.
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*
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* @private
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*/
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_calculateSpringForces : function() {
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var edgeLength, edge, edgeId;
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var dx, dy, fx, fy, springForce, length;
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var edges = this.edges;
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// forces caused by the edges, modelled as springs
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for (edgeId in edges) {
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if (edges.hasOwnProperty(edgeId)) {
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edge = edges[edgeId];
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if (edge.connected) {
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// only calculate forces if nodes are in the same sector
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if (this.nodes.hasOwnProperty(edge.toId) && this.nodes.hasOwnProperty(edge.fromId)) {
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edgeLength = edge.length;
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// this implies that the edges between big clusters are longer
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edgeLength += (edge.to.clusterSize + edge.from.clusterSize - 2) * this.constants.clustering.edgeGrowth;
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dx = (edge.from.x - edge.to.x);
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dy = (edge.from.y - edge.to.y);
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length = Math.sqrt(dx * dx + dy * dy);
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springForce = this.constants.physics.springConstant * (edgeLength - length) / length;
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fx = dx * springForce;
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fy = dy * springForce;
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edge.from.fx += fx;
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edge.from.fy += fy;
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edge.to.fx -= fx;
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edge.to.fy -= fy;
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}
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}
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}
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}
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},
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/**
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* This function calculates the springforces on the nodes, accounting for the support nodes.
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*
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* @private
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*/
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_calculateSpringForcesWithSupport : function() {
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var edgeLength, edge, edgeId, combinedClusterSize;
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var edges = this.edges;
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// forces caused by the edges, modelled as springs
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for (edgeId in edges) {
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if (edges.hasOwnProperty(edgeId)) {
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edge = edges[edgeId];
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if (edge.connected) {
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// only calculate forces if nodes are in the same sector
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if (this.nodes.hasOwnProperty(edge.toId) && this.nodes.hasOwnProperty(edge.fromId)) {
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if (edge.via != null) {
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var node1 = edge.to;
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var node2 = edge.via;
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var node3 = edge.from;
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edgeLength = edge.length;
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combinedClusterSize = node1.clusterSize + node3.clusterSize - 2;
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// this implies that the edges between big clusters are longer
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edgeLength += combinedClusterSize * this.constants.clustering.edgeGrowth;
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this._calculateSpringForce(node1,node2,0.5*edgeLength);
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this._calculateSpringForce(node2,node3,0.5*edgeLength);
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}
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}
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}
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}
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}
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},
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/**
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* This is the code actually performing the calculation for the function above. It is split out to avoid repetition.
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*
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* @param node1
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* @param node2
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* @param edgeLength
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* @private
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*/
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_calculateSpringForce : function(node1,node2,edgeLength) {
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var dx, dy, fx, fy, springForce, length;
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dx = (node1.x - node2.x);
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dy = (node1.y - node2.y);
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length = Math.sqrt(dx * dx + dy * dy);
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springForce = this.constants.physics.springConstant * (edgeLength - length) / length;
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fx = dx * springForce;
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fy = dy * springForce;
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node1.fx += fx;
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node1.fy += fy;
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node2.fx -= fx;
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node2.fy -= fy;
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}
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}
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