/// <summary>
/// Compute the shortest arc quaternion with a fixed yaw axis.
/// </summary>
/// <param name="direction">The direction to face. Must be normalized.</param>
/// <param name="yawFixedAxis">The axis to fix as yaw.</param>
/// <returns>The quaternion that will get to this orientation.</returns>
public static Quaternion shortestArcQuatFixedYaw(ref Vector3 direction, ref Vector3 yawFixedAxis)
{
Vector3 xVec = yawFixedAxis.cross(ref direction);
xVec.normalize();
Vector3 yVec = direction.cross(ref xVec);
yVec.normalize();
Quaternion targetWorldOrientation = new Quaternion();
targetWorldOrientation.fromAxes(xVec, yVec, direction);
return(targetWorldOrientation);
}
/// <summary>
/// Find the shortest arc, but first normalize the two vectors.
/// </summary>
/// <param name="v0">Source vector.</param>
/// <param name="v1">Destination vector.</param>
/// <returns>The quaternion with the shortest arc.</returns>
public static Quaternion shortestArcQuatNormalize2(ref Vector3 v0, ref Vector3 v1)
{
v0.normalize();
v1.normalize();
return(shortestArcQuat(ref v0, ref v1));
}