public static Vector3 ToIdealEulerAngles(this Quaterniond quat, string rotationOrder, bool usesX, bool usesY, bool usesZ)
{
// First get all possible euler representations of this quaternion rotation.
List <Vector3> eulerReps = quat.ToEulerAnglesRobust(rotationOrder);
// Then sort the representations by how close to ideal they are for storing.
var eulerRepsSorted = eulerReps.OrderBy(rep =>
{
// First sort by how little the representation would change upon being save and reloaded.
// e.g. (0, -135, 0) and (180, -45, 180) might be visually the same, but if we can't store the Z axis we want to use the former.
var storableRep = new Vector3(
usesX ? rep.X : 0,
usesY ? rep.Y : 0,
usesZ ? rep.Z : 0
);
var diff = storableRep - rep;
return(diff.Length);
});
eulerRepsSorted = eulerRepsSorted.ThenBy(rep =>
{
// Next sort by how few axes are nonzero.
// e.g. Between (0, 45, 90) and (-180, 135, -90), prefer the former because it looks neater and is more likely to be the original rotation read.
var numUsedAxes = 0;
if (Math.Abs(rep.X) >= 0.000001)
{
numUsedAxes += 1;
}
if (Math.Abs(rep.Y) >= 0.000001)
{
numUsedAxes += 1;
}
if (Math.Abs(rep.Z) >= 0.000001)
{
numUsedAxes += 1;
}
return(numUsedAxes);
});
// Return the most ideal representation.
return(eulerRepsSorted.First());
}