[vtk-developers] Why wasn't vtkCellArray in vtkPolyData designed similar to vtkCellLinks?

Mingcheng Chen linyufly at gmail.com
Fri Feb 10 15:01:12 EST 2012


Thanks Will!

Best regards,
Mingcheng Chen
February 10th, 2012

On Fri, Feb 10, 2012 at 9:37 PM, Will Schroeder
<will.schroeder at kitware.com>wrote:

> In the early days of VTK it was envisioned as a "read-only" system where
> data was loaded and then viewed. The idea was to minimize data structure
> size (as Dave says) yet enable more
> sophisitcated topological representations on an incremental / as needed
> basis.
>
> With the success of VTK its usage pattern has changed. Many of us now want
> to load and edit structures. Work has been done to create full-blown
> topological hierarchies in VTK to support complex mesh editing operations
> and engineering simulation (like adaptive refinement). While these have not
> yet fully made their way into VTK proper, it is likely such structures will
> be added to the system as funding and support becomes available.
>
> W
>
>
> On Fri, Feb 10, 2012 at 8:28 AM, David E DeMarle <dave.demarle at kitware.com
> > wrote:
>
>> Because iteration is the more common access pattern (most importantly
>> when pushing the elements to GL). Thus making the primary structure a
>> sequential layout and making the random access layout optional saves
>> both time and memory.
>>
>> David E DeMarle
>> Kitware, Inc.
>> R&D Engineer
>> 21 Corporate Drive
>> Clifton Park, NY 12065-8662
>> Phone: 518-881-4909
>>
>>
>>
>> On Thu, Feb 9, 2012 at 7:26 PM, Mingcheng Chen <linyufly at gmail.com>
>> wrote:
>> > Hi all,
>> >
>> > Currently, without vtkCellTypes we cannot randomly access cell in poly
>> data
>> > because there is no uniform "entry length" in vtkCellArray (cells may
>> have
>> > different number of connectivities).
>> >
>> > However, vtkCellLinks can support random access for every point,
>> because it
>> > uses local linked list in each entry.
>> >
>> > Why wasn't vtkCellArray designed like vtkCellLinks? If so, we can deal
>> with
>> > only three arrays instead of four.
>> >
>> > Could anyone please help me with that puzzle? What is the advantage of
>> the
>> > current design?
>> >
>> > Thanks!
>> >
>> > Best regards,
>> > Mingcheng Chen
>> > February 9th, 2012
>> >
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>
>
> --
> William J. Schroeder, PhD
> Kitware, Inc.
> 28 Corporate Drive
> Clifton Park, NY 12065
> will.schroeder at kitware.com
> http://www.kitware.com
> (518) 881-4902
>



-- 
Mingcheng Chen

Research Assistant in Graphics Group
University of Illinois at Urbana-Champaign

---------------------------------------------------------
Below is my undergraduate information.
---------------------------------------------------------
Personal Page: http://epcc.sjtu.edu.cn/~mingchengchen
Embedded and Pervasive Computing Center
Shanghai Jiao Tong University
No.800 Dongchuan Road, Minhang District, Shanghai, PRC
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