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.
89 lines
2.8 KiB
89 lines
2.8 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;
|
|
|
|
// handle the case where one node is not part of the physcis
|
|
if (this.physicsBody.forces[node1.id] !== undefined) {
|
|
this.physicsBody.forces[node1.id].x += fx;
|
|
this.physicsBody.forces[node1.id].y += fy;
|
|
}
|
|
|
|
if (this.physicsBody.forces[node2.id] !== undefined) {
|
|
this.physicsBody.forces[node2.id].x -= fx;
|
|
this.physicsBody.forces[node2.id].y -= fy;
|
|
}
|
|
}
|
|
}
|
|
|
|
export default SpringSolver;
|