vis.js is a dynamic, browser-based visualization library
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 

83 lines
2.6 KiB

/**
* Created by Alex on 2/23/2015.
*/
class SpringSolver {
constructor(body, physicsBody, options) {
this.body = body;
this.physicsBody = physicsBody;
this.setOptions(options);
}
setOptions(options) {
this.options = options;
}
/**
* This function calculates the springforces on the nodes, accounting for the support nodes.
*
* @private
*/
solve() {
var edgeLength, edge;
var edgeIndices = this.physicsBody.physicsEdgeIndices;
var edges = this.body.edges;
// forces caused by the edges, modelled as springs
for (let i = 0; i < edgeIndices.length; i++) {
edge = edges[edgeIndices[i]];
if (edge.connected === true) {
// only calculate forces if nodes are in the same sector
if (this.body.nodes[edge.toId] !== undefined && this.body.nodes[edge.fromId] !== undefined) {
if (edge.edgeType.via !== undefined) {
edgeLength = edge.options.length === undefined ? this.options.springLength : edge.options.length;
var node1 = edge.to;
var node2 = edge.edgeType.via;
var node3 = edge.from;
this._calculateSpringForce(node1, node2, 0.5 * edgeLength);
this._calculateSpringForce(node2, node3, 0.5 * edgeLength);
}
else {
// the * 1.5 is here so the edge looks as large as a smooth edge. It does not initially because the smooth edges use
// the support nodes which exert a repulsive force on the to and from nodes, making the edge appear larger.
edgeLength = edge.options.length === undefined ? this.options.springLength * 1.5: edge.options.length;
this._calculateSpringForce(edge.from, edge.to, edgeLength);
}
}
}
}
}
/**
* This is the code actually performing the calculation for the function above.
*
* @param node1
* @param node2
* @param edgeLength
* @private
*/
_calculateSpringForce(node1, node2, edgeLength) {
var dx, dy, fx, fy, springForce, distance;
dx = (node1.x - node2.x);
dy = (node1.y - node2.y);
distance = Math.sqrt(dx * dx + dy * dy);
distance = distance == 0 ? 0.01 : distance;
// the 1/distance is so the fx and fy can be calculated without sine or cosine.
springForce = this.options.springConstant * (edgeLength - distance) / distance;
fx = dx * springForce;
fy = dy * springForce;
this.physicsBody.forces[node1.id].x += fx;
this.physicsBody.forces[node1.id].y += fy;
this.physicsBody.forces[node2.id].x -= fx;
this.physicsBody.forces[node2.id].y -= fy;
}
}
export default SpringSolver;