private void ApplySprings()
{
for (int i = 0, edgesCount = fEdges.Count; i < edgesCount; i++)
{
ArborEdge edge = fEdges[i];
ArborPoint s = edge.Target.Pt.Sub(edge.Source.Pt);
ArborPoint r = s.Normalize();
double q = edge.Stiffness * (edge.Length - s.Magnitude());
edge.Source.ApplyForce(r.Mul(q * -0.5f));
edge.Target.ApplyForce(r.Mul(q * 0.5f));
}
}
public void Test_Mul()
{
var pt = new ArborPoint(3, 4);
Assert.AreEqual(3.0f, pt.X);
Assert.AreEqual(4.0f, pt.Y);
pt = pt.Mul(5);
Assert.AreEqual(15.0f, pt.X);
Assert.AreEqual(20.0f, pt.Y);
}
private void UpdateVelocityAndPosition(double dt)
{
int nodesCount = fNodes.Count;
if (nodesCount == 0)
{
fEnergyMax = 0.0f;
fEnergyMean = 0.0f;
fEnergySum = 0.0f;
return;
}
double eMax = 0.0f;
double eSum = 0.0f;
// calc center drift
ArborPoint rr = ArborPoint.Zero;
for (int i = 0; i < nodesCount; i++)
{
ArborNode node = fNodes[i];
rr = rr.Sub(node.Pt);
}
ArborPoint drift = rr.Div(nodesCount);
// main updates loop
for (int i = 0; i < nodesCount; i++)
{
ArborNode node = fNodes[i];
// apply center drift
node.ApplyForce(drift);
// apply center gravity
if (fGravity)
{
ArborPoint q = node.Pt.Mul(-1.0f);
node.ApplyForce(q.Mul(fRepulsion / 100.0f));
}
// update velocities
if (node.Fixed)
{
node.V = ArborPoint.Zero;
}
else
{
node.V = node.V.Add(node.F.Mul(dt));
node.V = node.V.Mul(1.0f - fFriction);
double r = node.V.MagnitudeSquare();
if (r > 1000000.0f)
{
node.V = node.V.Div(r);
}
}
node.F = ArborPoint.Zero;
// update positions
node.Pt = node.Pt.Add(node.V.Mul(dt));
// update energy
double energy = node.V.MagnitudeSquare();
eSum += energy;
eMax = Math.Max(energy, eMax);
}
fEnergyMax = eMax;
fEnergyMean = eSum / nodesCount;
fEnergySum = eSum;
}
