protected virtual void UpdatePositions(TimeSpan duration)
{
double timeFactor = (duration.TotalMilliseconds / 25) * time;
time = MathTools.Clip(time, 0.1, 10);
foreach (Node node in quadTree.AllNodes())
{
if (node.IsSelected || node.IsPositionLocked)
{
// reset force
node.TotalForce = new Vector();
node.Velocity = new Vector();
}
// add drag, todo: should be proportional to V, plus a fixed amount
node.TotalForce -= (node.Velocity * friction);
//if (node.Velocity.Length > 0)
//{
// double dragStrength = 0.2 + (node.Velocity.LengthSquared / 100) * friction;
// Vector dragForce = node.Velocity;
// dragForce.Normalize();
// dragForce *= dragStrength;
// node.TotalForce -= dragForce;
//}
// calculate the acceleration, F = MA
Vector acceleration = node.TotalForce / node.Mass;
// calculate the new velocity, todo: should be V = AT
node.Velocity += acceleration * timeFactor;
// calculate the new position, V = D/T
node.Position += node.Velocity * timeFactor;
// reset force
node.TotalForce = new Vector();
quadTree.UpdateNodeQuadrant(node);
}
}
/// <summary>
/// Gets the smallest rect that contains all the nodes
/// </summary>
public Rect GetContentBounds()
{
Rect contentBounds = quadTree.AllNodes().Select(n => n.GetBounds()).GetBounds();
return(contentBounds);
}
