private void applySprings()
{
foreach (ArborEdge edge in fEdges)
{
ArborPoint s = edge.Target.Pt.sub(edge.Source.Pt);
double sMag = s.magnitude();
ArborPoint r = ((sMag > 0) ? s : ArborPoint.newRnd(1)).normalize();
double q = edge.Stiffness * (edge.Length - sMag);
edge.Source.applyForce(r.mul(q * -0.5));
edge.Target.applyForce(r.mul(q * 0.5));
}
}
private void updateVelocityAndPosition(double dt)
{
int size = fNodes.Count;
if (size == 0)
{
EnergySum = 0;
EnergyMax = 0;
EnergyMean = 0;
return;
}
double eSum = 0;
double eMax = 0;
// calc center drift
ArborPoint rr = new ArborPoint(0, 0);
foreach (ArborNode node in fNodes)
{
rr = rr.sub(node.Pt);
}
ArborPoint drift = rr.div(size);
// main updates loop
foreach (ArborNode node in fNodes)
{
// apply center drift
node.applyForce(drift);
// apply center gravity
if (ParamGravity)
{
ArborPoint q = node.Pt.mul(-1);
node.applyForce(q.mul(ParamRepulsion / 100));
}
// update velocities
if (node.Fixed)
{
node.V = new ArborPoint(0, 0);
}
else
{
node.V = node.V.add(node.F.mul(dt));
node.V = node.V.mul(1 - ParamFriction);
double r = node.V.magnitudeSquare();
if (r > 1000000)
{
node.V = node.V.div(r);
}
}
node.F.X = node.F.Y = 0;
// update positions
node.Pt = node.Pt.add(node.V.mul(dt));
// update energy
double z = node.V.magnitudeSquare();
eSum += z;
eMax = Math.Max(z, eMax);
}
EnergySum = eSum;
EnergyMax = eMax;
EnergyMean = eSum / size;
}