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114 lines
3.5 KiB
114 lines
3.5 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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_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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this.barnesHutTree = undefined;
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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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this._calculateSpringForces();
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},
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_calculateGravitationalForces : function() {
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var dx, dy, angle, fx, fy, node, i;
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var nodes = this.nodes;
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var gravity = this.constants.physics.centralGravity;
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for (i = 0; i < this.nodeIndices.length; i++) {
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node = nodes[this.nodeIndices[i]];
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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;// + screenCenterPos.x;
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dy = -node.y;// + screenCenterPos.y;
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angle = Math.atan2(dy, dx);
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fx = Math.cos(angle) * gravity;
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fy = Math.sin(angle) * gravity;
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}
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else {
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fx = 0;
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fy = 0;
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}
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node._setForce(fx, fy);
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node.updateDamping(this.nodeIndices.length);
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}
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},
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_calculateSpringForces : function() {
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var dx, dy, angle, fx, fy, springForce, length, edgeLength, edge, edgeId;
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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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dx = (edge.to.x - edge.from.x);
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dy = (edge.to.y - edge.from.y);
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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.growthIndicator + edge.from.growthIndicator) * this.constants.clustering.edgeGrowth;
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length = Math.sqrt(dx * dx + dy * dy);
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angle = Math.atan2(dy, dx);
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springForce = this.constants.physics.springConstant * (edgeLength - length);
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fx = Math.cos(angle) * springForce;
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fy = Math.sin(angle) * springForce;
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edge.from._addForce(-fx, -fy);
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edge.to._addForce(fx, 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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