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101 lines
2.6 KiB
101 lines
2.6 KiB
/**
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* Created by Alex on 2/23/2015.
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*/
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function SpringSolver(body, options) {
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this.body = body;
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this.options = options;
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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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SpringSolver.prototype._calculateSpringForces = function () {
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var 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 === true) {
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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.physics.springLength;
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this._calculateSpringForce(edge.from, edge.to, 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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* 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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SpringSolver.prototype._calculateSpringForcesWithSupport = function () {
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var 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 === true) {
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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.physics.springLength;
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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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SpringSolver.prototype._calculateSpringForce = function (node1, node2, edgeLength) {
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var dx, dy, fx, fy, springForce, distance;
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dx = (node1.x - node2.x);
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dy = (node1.y - node2.y);
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distance = Math.sqrt(dx * dx + dy * dy);
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distance = distance == 0 ? 0.01 : distance;
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// the 1/distance is so the fx and fy can be calculated without sine or cosine.
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springForce = this.options.springConstant * (edgeLength - distance) / distance;
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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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module.exports = SpringSolver;
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