Re: [boost] Interest in a new generic matrix library with specific 3D operations?

Subject: Re: [boost] Interest in a new generic matrix library with specific 3D operations?
From: Fabien Picarougne (fabien.picarougne_at_[hidden])
Date: 2014-07-03 17:55:20

Thank you for your very interesting remarks.
I did not know the QVM library and I have spent a little time to understand
it.
Initially, Traits was in my future plans, but the work that has been done on
QVM is more developed that what was in my mind.
But, in my understanding, there are some differences in our two approaches.
I understand the intent of QVM and I agree with that. In my case, the main
objective was to factor methods (to avoid writing the same thing twice) and
to do a maximum of calculations during compile time. It explains the global
usage of CRTP in my classes.
I think there is another difference in the design of both library in the
usage of specialization. In what I understand, QVM uses enable_if pattern to
achieve this specialization, and I use template specialization. I see here
some advantages of both approaches: you can group different specializations
in a single class in QVM (and not in my library) and you group
specializations for a particular type in my library (I guess it can also be
done in a way in QVM). But I cannot honestly say here what paradigm is the
best...

Regards,
Fabien

-----Message d'origine-----
De : Boost [mailto:boost-bounces_at_[hidden]] De la part de Adam
Wulkiewicz
Envoyé : jeudi 3 juillet 2014 14:35
À : boost_at_[hidden]
Objet : Re: [boost] Interest in a new generic matrix library with specific
3D operations?

Emil Dotchevski wrote:
> The QVM library is more generic.
>
> In my experience, while the interface of the operations of a vector/matrix
> library can be standardized, it is often impractical to standardize the
> vector and matrix types themselves, because different use cases demand
> different compromise between ease of use and performance. For example, 16
> or 32-byte alignment may result in maximum speed but that isn't always the
> best option.
>
> That's why the emphasis in the QVM library is on the generic nature of the
> operations: they are independent of any types and can kick-in for any
> user-defined or third-party matrix/vector types (and of course types that
> QVM itself emits).
>
> This allows developers to define platform-, project- or even
> module-specific types and the full set of QVM operations become available
> automatically. Later, if necessary, profiler-guided optimizations can
> target only a critical subset of the types and the operations; e.g. one
can
> overload to optimize only operator*, and only for some aligned_mat44 type
> (overload resolution will always prefer such user-defined overloads over
> the QVM overloads.)
>

Yes, the QVM design is more generic. This is why I proposed to use the 
concepts from this library in the implementation of the algorithms.

To be more precise, I thought about domain-specific algorithms. In this 
case from computer graphics but tools for other domains like robotics or 
physics could be implemented as well, e.g.:
- functions for handling view and perspective (implemented by Fabien as 
SetOrtho(), SetFrustum(), SetLookAt(), etc.),
- some generic Rotation concept allowing to represent it (in 3D) as 
axis-angle, matrix3x3 or quaternion, which could just be simply applied 
to e.g. a Vector in a unified way,
- the conversions between various representations,
- similar thing with Orientation - rotation + translation (e.g. 
matrix3x4 or quaternion and a vector),
- similar thing with Transformation - the above + scale (e.g. matrix4x4 
or quaternion and some vectors),
- differential operators like gradient, divergence, etc. and probably a 
VectorField concept,
- most certainly many more...

Of course we should debate if and where such domain-specific algorithms 
could be put.
But this is also true for QVM I guess.

A little off-topic...
Would it be difficult to extend QVM to use e.g. Boost.SIMD in the future?
E.g. provide additional traits defining the alignment of the data and 
use vectorization accordingly?

Regards,
Adam

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