/// <summary>
///
/// </summary>
/// <param name="time"></param>
/// <param name="quatA"></param>
/// <param name="quatB"></param>
/// <param name="useShortestPath"></param>
/// <returns></returns>
public static Quaternion Slerp(float time, Quaternion quatA, Quaternion quatB, bool useShortestPath)
{
float cos = quatA.Dot(quatB);
float angle = MathUtil.ACos(cos);
if(MathUtil.Abs(angle) < EPSILON) {
return quatA;
}
float sin = MathUtil.Sin(angle);
float inverseSin = 1.0f / sin;
float coeff0 = MathUtil.Sin((1.0f - time) * angle) * inverseSin;
float coeff1 = MathUtil.Sin(time * angle) * inverseSin;
Quaternion result;
if(cos < 0.0f && useShortestPath) {
coeff0 = -coeff0;
// taking the complement requires renormalisation
Quaternion t = coeff0 * quatA + coeff1 * quatB;
t.Normalize();
result = t;
}
else {
result = (coeff0 * quatA + coeff1 * quatB);
}
return result;
}
/// <summary>
///
/// </summary>
/// <param name="time"></param>
/// <param name="quatA"></param>
/// <param name="quatB"></param>
/// <param name="useShortestPath"></param>
/// <returns></returns>
public static Quaternion Nlerp(float time, Quaternion quatA, Quaternion quatB, bool shortestPath)
{
Quaternion result;
float cos = quatA.Dot(quatB);
if (cos < 0.0f && shortestPath) {
result = quatA + time * ((-1 * quatB) + (-1 * quatA));
}
else {
result = quatA + time * (quatB + (-1 * quatA));
}
result.Normalize();
return result;
}
