/// <summary>
/// Get the spherically interpolated quaternion at position t between
/// a and b (UNVERIFIED)
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <param name="t"></param>
/// <returns></returns>
static public Quaternion Slerp(Quaternion a, Quaternion b, float t)
{
// TODO: verify the validity of this function
Debug.WriteLine("Quaternion.Slerp() - warning, this function has not be checked for validity.");
// Calculate the cosine of the angle between the two
float fScale0, fScale1;
double dCos = Quaternion.DotProduct(a, b);
// If the angle is significant, use the spherical interpolation
if ((1.0 - Math.Abs(dCos)) > 1e-6f)
{
double dTemp = Math.Acos(Math.Abs(dCos));
double dSin = Math.Sin(dTemp);
fScale0 = (float)(Math.Sin((1.0 - t) * dTemp) / dSin);
fScale1 = (float)(Math.Sin(t * dTemp) / dSin);
}
// Else use the cheaper linear interpolation
else
{
fScale0 = 1.0f - t;
fScale1 = t;
}
if (dCos < 0.0)
{
fScale1 = -fScale1;
}
// Return the interpolated result
return((a * fScale0) + (b * fScale1));
}
