[vtk-developers] Crossing library boundaries

[Jim Peterson]

David,
In principle, I agree, if a function is truly isolated, and capable of 
being used globally it can be "moved up" in the library sequence, moving 
the vtkLandmarkTransform to common would do that. With the fact that 
vtkLandmarkTransform is an extension of the vtkLinearTransform which is 
in Common currently, I don't see a major issue.  I would be very careful 
about this line of thinking though, continuing along this path will 
migrate everything to Common eventually. It might be worth someone's 
time to examine the Hybrid contents periodically to see if there is a 
more natural home for some contents. I suspect the Control library was 
renamed to Hybrid because of the cross library implementations that may 
be there.

In reference to actually changing vtk, vtk is an enormous system, and 
again, I am outside my comfort zone in actual knowlege. Regarding the 
transforms themselves, I am not what I would call informed with the 
range of transforms present in vtk. I find 27 different transform 
classes across 5 libraries, with 14 in Common, 2 in Geovis, 4 in 
Graphics, 6 in Hybrid, and one in Rendering. I know for sure I have not 
directly used more than 2 or 3 myself.

and as far as the vtkArrowSource, isn't it just a tube with a cone at 
the end? And are there any uses in any of the existing examples? What is 
so special about the straight line? if we are going to make something 
generally useful, shouldn't it be able to follow any line source (like a 
vtkTubeFilter) and "cap" the tube with a Cone?

I appologize for ranting if that is what I am doing, and I admit it is 
kind of selfish, if this system keeps growing, I will never be able to 
get to the point that I have learned it.

In software we too often have a solution that is desperately looking for 
a problem,  and that generally leads to software bloat and additional 
complexity.
HTH
Jim

David Doria wrote:
> On Wed, Sep 15, 2010 at 1:49 PM, Bill Lorensen 
> <bill.lorensen at gmail.com <mailto:bill.lorensen at gmail.com>> wrote:
>
>     look here:
>     http://vtk.org/Wiki/VTK/Examples/Cxx/GeometricObjects/OrientedArrow
>
>     maybe not easier, but another way.
>
>
> Bill, my method is here (the AlignRays function (not fully tested yet 
> because of the linker errors) ):
> http://github.com/daviddoria/daviddoria-vtk/commit/e97738896ed41aa007424f9fefb5a5d2a9a0aa78
>
> Jim, if David Gobbi is right and we can move vtkLandmarkTransform to 
> Common then it would be fine to allow vtkArrowSource to accept a 
> Point1 and Point2, right?
>
> David G, if we don't hear any screaming would you volunteer to verify 
> my commit of moving vtkLandmarkTransform to Common (to github) before 
> we push to VTK master?
>
> Thanks,
>
> David D.
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