[vtkusers] Deforming mesh.

[Rodrigo Pinheiro]

Dear Nark,

    I know it can sound strange, but if you go to the source code, you will 
get a good insight on how to implement that.
    I have been working with VTK for non-linear transient finite element 
results visualisation. I am using vtk 3.2, so my codes are out-of-date, but 
the concept should remains the same.
    For the dataset, I have two possibilities:
    - No adaptivity. The polygons and points datasets are constant, only the 
coords should be updated. There are functions you can use for doing that, 
but depends on yous data structure. I don´t use the vtk pipeline for that, 
the idea is to have the coord vector for each state already loaded into the 
memory, and just replace the pointer whenever you need. It is faster, but 
requires more memory (but you can work arround and optimize the memory 
using). Another way can be reading the coords from file as necessary. I am 
using HDF5 as file standard, and doing so I can easily control the dataset 
being read from the file.
    - With adaptivity. The polygons and points datasets are always changing 
from step to step. In this case, I have an actor for each state, which I 
turn on and of as necessary.

    Another problem is the timer. Depending the platform you are working, 
the implementation will be different. With windows and VC++, you can set a 
timer and answer to a "timer" message with a specific function that will 
prepare the necessary changes for you and call the renderer update.

    Please, if you can send me more information, I will be gald to inform 
more details about the code.

Regards,

Rodrigo



>From: Mark Foskey <mark_foskey at unc.edu>
>To: vtkusers at public.kitware.com
>Subject: [vtkusers] Deforming mesh.
>Date: Sun, 23 Feb 2003 18:55:20 -0500
>
>Is there a standard way to render a polygonal mesh that is being
>deformed over time?  I envision grabbing the point data by something
>like GetPoint() or GetPointData() and then modifying it.  But it's not 
>clear from the documentation that I get pointers to the actual data rather 
>than a copy.
>
>I'm also thinking I will want to subclass an InteractorStyle and use a 
>Timer, but I can't find documentation for how frequently Timer events go 
>off, or for what the significance of creating and destroying a timer is. 
>Perhaps the documentation for CreateTimer() should be written on a more 
>elementary level, even maybe with more background.  The same applies to the 
>comment for vtkInteractorStyle::OnTimer() -- why does it only run when the 
>mouse button is down, for instance?  (There' also is a small typo -- it 
>should read "Rotate, Spin, etc", not "Rotate, Rotate, etc", right?)
>
>Thanks for any help,
>Mark
>
>--
>Mark Foskey    (919) 843-5436  Computer-Aided Diagnosis and Display Lab
>mark_foskey at unc.edu            Department of Radiology, CB 7515, UNC
>http://www.cs.unc.edu/~foskey  Chapel Hill, NC  27599-7515
>
>
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