[vtk-developers] holes in documentation

Will Schroeder will.schroeder at kitware.com
Fri Dec 21 06:40:53 EST 2007


Open source software means pitching in when you see problems :-) We all know
that the documentation needs improvement; but given the size of the system
and the velocity of development; it is hard to keep up with it and
volunteers are needed. We are looking forward to your contributions ;-)


On 12/20/07, kent williams <nkwmailinglists at gmail.com> wrote:
> I don't have the current VTK book -- I have 3rd Edition, but it seems
> to me that there are some rather gaping holes in the documentation for
> VTK that I come across.
> Here's one example that I've spent a while scratching my head over:
> There is a static member function vtkPolygon::PointInPolygon. Great! I
> don't have to look that one up, code and debug it!
> But, look at the function signature:
> int vtkPolygon::PointInPolygon (double x[3], int numPts, double *pts,
>                                 double bounds[6], double *n)
> I think I can assume that the 'pts' parameter points to an array of 3D
> points -- i.e. x,y,z,x,y,z,x,y,z etc.  But does it say that anywhere?
> I have to infer that from reading the source code.
> Furthermore, nowhere does it explain that the parameter 'n' is the
> normal of the polygon -- again I found that out by reading the source.
> More mysteries: how do I construct a vtkPolygon from a list of points?
> Is there any real use for a naked vtkPolygon?
> Every example I can find that appears relevant to these questions does
> mystifying things with vtkCells without any comments explaining what's
> going on. My one best effort of dealing with vtkCell coding directly
> was a miserable failure.
> Everything to do with vtkCell and descendents is PFM to anyone except
> the implementers.  I'm not the brightest programmer in the world but
> I've been banging my head on this stuff for quite a while now, and it
> seems to me that there could be better Doxygen comments.
> And it wouldn't hurt to have better documentation of VTK internals
> because, unfortunately, any sort of information hiding seems to fall
> apart any time I try and do anything non-trivial. The internals don't
> stay internal, either because of gaps in the API, or for lack of any
> convenient higher-level interface to leave the book-keeping behind the
> curtain.
> This may seem like just bellyaching, and maybe it is, but I can't be
> the only person who has gotten frustrated trying to understand VTK.
> Really, I appreciate all the great things VTK can do for me, and I
> only want it to become better, and easier to use.
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William J. Schroeder, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
518-371-3971 (phone and fax)
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