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.
72 lines
2.0 KiB
72 lines
2.0 KiB
class RepulsionSolver {
|
|
constructor(body, physicsBody, options) {
|
|
this.body = body;
|
|
this.physicsBody = physicsBody;
|
|
this.setOptions(options);
|
|
}
|
|
|
|
setOptions(options) {
|
|
this.options = options;
|
|
}
|
|
|
|
/**
|
|
* Calculate the forces the nodes apply on each other based on a repulsion field.
|
|
* This field is linearly approximated.
|
|
*
|
|
* @private
|
|
*/
|
|
solve() {
|
|
var dx, dy, distance, fx, fy, repulsingForce, node1, node2;
|
|
|
|
var nodes = this.body.nodes;
|
|
var nodeIndices = this.physicsBody.physicsNodeIndices;
|
|
var forces = this.physicsBody.forces;
|
|
|
|
// repulsing forces between nodes
|
|
var nodeDistance = this.options.nodeDistance;
|
|
|
|
// approximation constants
|
|
var a = (-2 / 3) / nodeDistance;
|
|
var b = 4 / 3;
|
|
|
|
// we loop from i over all but the last entree in the array
|
|
// j loops from i+1 to the last. This way we do not double count any of the indices, nor i === j
|
|
for (let i = 0; i < nodeIndices.length - 1; i++) {
|
|
node1 = nodes[nodeIndices[i]];
|
|
for (let j = i + 1; j < nodeIndices.length; j++) {
|
|
node2 = nodes[nodeIndices[j]];
|
|
|
|
dx = node2.x - node1.x;
|
|
dy = node2.y - node1.y;
|
|
distance = Math.sqrt(dx * dx + dy * dy);
|
|
|
|
// same condition as BarnesHutSolver, making sure nodes are never 100% overlapping.
|
|
if (distance === 0) {
|
|
distance = 0.1*Math.random();
|
|
dx = distance;
|
|
}
|
|
|
|
if (distance < 2 * nodeDistance) {
|
|
if (distance < 0.5 * nodeDistance) {
|
|
repulsingForce = 1.0;
|
|
}
|
|
else {
|
|
repulsingForce = a * distance + b; // linear approx of 1 / (1 + Math.exp((distance / nodeDistance - 1) * steepness))
|
|
}
|
|
repulsingForce = repulsingForce / distance;
|
|
|
|
fx = dx * repulsingForce;
|
|
fy = dy * repulsingForce;
|
|
|
|
forces[node1.id].x -= fx;
|
|
forces[node1.id].y -= fy;
|
|
forces[node2.id].x += fx;
|
|
forces[node2.id].y += fy;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
export default RepulsionSolver;
|