public static Quaternion FactoryFromAxisAngle(Vector axis, float angle)
{
if (axis.LengthSquared() == 0.0f)
return FactoryIdentity;
float sinAngleOverAxisLength = Calc.Sin(angle / 2) / axis.Length();
return Quaternion.Normalize(new Quaternion(
axis.X * sinAngleOverAxisLength,
axis.Y * sinAngleOverAxisLength,
axis.Z * sinAngleOverAxisLength,
Calc.Cos(angle / 2)));
}
