public static F64Quat LookRotation(F64Vec3 dir, F64Vec3 up)
{ // From: https://answers.unity.com/questions/819699/calculate-quaternionlookrotation-manually.html
if (dir == F64Vec3.Zero)
{
return(Identity);
}
if (up != dir)
{
up = F64Vec3.NormalizeFastest(up);
F64Vec3 v = dir + up * -F64Vec3.Dot(up, dir);
F64Quat q = FromTwoVectors(F64Vec3.AxisZ, v);
return(FromTwoVectors(v, dir) * q);
}
else
{
return(FromTwoVectors(F64Vec3.AxisZ, dir));
}
}
public static F64Quat LookAtRotation(F64Vec3 from, F64Vec3 to, F64Vec3 up)
{
F64Vec3 dir = F64Vec3.NormalizeFastest(to - from);
return(LookRotation(dir, up));
}