public void Reset()
{
InitialVelocity = new VectorF(0, 0);
InitialAngularVelocity = 0;
InitialExpansionVelocity = 0;
stopwatch.Reset();
stopwatch.Start();
}
//update velocities, velocity = distance/time
public void Update(ManipulationDeltaEventArgs e, float history)
{
float elappsedMS = stopwatch.ElapsedMilliseconds;
if (elappsedMS == 0)
elappsedMS = 1;
InitialVelocity = InitialVelocity * history + ((VectorF)e.TranslationDelta * (1F - history)) / elappsedMS;
InitialAngularVelocity = InitialAngularVelocity * history + (e.RotationDelta * (1F - history)) / elappsedMS;
InitialExpansionVelocity = InitialExpansionVelocity * history + (e.ExpansionDelta * (1F - history)) / elappsedMS;
stopwatch.Reset();
stopwatch.Start();
}