[vtkusers] how to access multiple point or cell scalars at the same time

[Jingsheng Ma]

Hi there,

I am trying to write a program to access multiple scalars, vectors or
tensors of point or cell data in the same dataset at the same time. This is
often required in, for example, mechanic and fluid simulation. 

Assume we have a vtk data set of the a simulation and this data set contains
displacement and fluid velocity vectors on points. Clearly we would like to
see both deformation of grid and fluid velocity in some forms, such as
streamlines or vertor arrows, at the same time.  

As far as I know, if the displacement vector is set to be the attribute to
be extracted from the dataset with a reader object of a vtkDataReader
subclass, using vtkWarpVector will do the job of showing the deformation of
the grid, but then the fluid velocity vector can't be used subsequently in
the same pipeline.

Is this correct? If not, can someone explain why? if it is true, what would
be the best approach to implement the above.

Or my problem may be stated in a more simple way. Can vtkWarpVector take a
vector which has not be selected by the reader? If so how to do this?  


Many thanks in advance.


Dr. Jingsheng Ma
Dept. of Petroleum Engineering
Heriot-Watt University
Edinburgh, EH14 4AS

Tel: +44 (0)131 451 3675