Re: [eigen] Do we need geometry refactoring?

[Manuel Yguel <manuel.yguel@xxxxxxxxx>]

> - Some users are happy because their old code keeps working
Sorry, if I let pass that kind of frustration in my last mail :)

- begin of sycophant mode -
In my experience, most of the time, the decisions made by the
developers are the best.
- end of sycophant mode -

I just take a look at the code and:
I have seen the new Mode parameter. Using it properly, just solve my
problem very quickly (I had just to change one line of code to fix the
whole problem, typedefs are really handy).
To take my share on the default discussion:
well, I do not really care, as long as I know it, and I should have
since I read that thread,
(by the way the documentation contains an error regarding that
specific part: it is said that affine is the default).

The more general is generally the better for a default parameter
however calling Transform3x a general 4d transformation is weird.
If I understand correctly Hauke point, the graal  would be to detect
the following programming mistake:
 a composition of transformations with a non affine result used
(thought as) an affine transform.
I do not see how to do that really, but I agree with the goal.

Perhaps an alternative would be that Transform3x is Affine but not the
default parameter of the class Transform ?

- best regards,

Manuel

>
> cons against switching back:
> - It is unintuitive that the most generic Transformation is affine
> - Some users are unhappy because expectedly correct code like this
> produces wrong results (one of my strongest arguments)
>
> Transform3f T( some_projective_4x4_matrix );
> Vector3f v;
> T*v
>
> "Hmm, and I was sure I read that Transform3f's model non-linear
> transformations!??"
> - In 90% of the cases, we can be hope (I admit this is not a strong
> argument) that the users will get a compile time error for the example
> in question because the fixed size dims are not fitting (v' = T*v when
> T is projective)
> - Last chance to get things right since Eigen 3 will anyways break
> lots of Eigen 2 code or we are stuck with this forever
> - It is the right thing to do .... ;)
>
> Ok, I am passing the choice back to you and other people on the list.
> As I said, outvote me and I will revert this change.
>
> Regards,
> - Hauke
>
>
>