/// <summary>
/// Advances the world model by one frame.
/// </summary>
public void Update()
{
// Update nodes.
lock (_nodeLock) {
// Update the nodes and determine required tree width.
double halfWidth = 0;
foreach (Node node in _nodes)
{
node.Update();
halfWidth = Math.Max(Math.Abs(node.Location.X), halfWidth);
halfWidth = Math.Max(Math.Abs(node.Location.Y), halfWidth);
halfWidth = Math.Max(Math.Abs(node.Location.Z), halfWidth);
}
Radius = halfWidth;
// Build tree for node repulsion.
Octree tree = new Octree(2.1 * halfWidth);
foreach (Node node in _nodes)
{
tree.Add(node);
}
Threading.Parallel.ForEach(_nodes, node => {
// Apply repulsion between nodes.
tree.Accelerate(node);
// Apply origin attraction of nodes.
//Vector originDisplacementUnit = -node.Location.Unit();
Vector origin = (node.Group == null) ? Vector.Zero : node.Group.Origin;
Vector originDisplacementUnit = Unit(origin - node.Location);
double originDistance = (origin - node.Location).Magnitude();
double attractionCofficient = OriginFactor;
if (originDistance < OriginWeakDistance)
{
attractionCofficient *= originDistance / OriginWeakDistance;
}
// Apply group's attraction factor
//attractionCofficient *= (node.Group == null) ? 1 : node.Group.Factor;
//node.Acceleration += originDisplacementUnit * attractionCofficient / (originDistance + OriginEpsilon);
Vector originAcceleration = originDisplacementUnit * attractionCofficient / (originDistance + OriginEpsilon);
if (node.Group != null)
{
originAcceleration.X *= node.Group.Factor.X;
originAcceleration.Y *= node.Group.Factor.Y;
originAcceleration.Z *= node.Group.Factor.Z;
}
node.Acceleration += originAcceleration;
// Apply edge spring forces.
foreach (Node other in node.Connected)
{
Vector displacement = node.Location.To(other.Location);
//Vector direction = displacement.Unit();
Vector direction = Unit(displacement);
double distance = displacement.Magnitude();
//double idealLength = EdgeLength + node.Radius + other.Radius;
// Set a large mass if it's in different groups
double mass = (node.Group != other.Group) ? 1000 : node.Mass;
double idealLength = EdgeLength + Node.GetRadius(mass) + other.Radius;
node.Acceleration += direction * EdgeFactor * (distance - idealLength) / mass;
//node.Acceleration += direction * EdgeFactor * (distance - idealLength) / node.Mass;
}
});
}
}
