[Paraview] Comparative views

[Jean Favre]

Comparative viewing is a great tool to look at multiple timesteps. While 
preparing our next set of tutorial, I am running against the following 
issues:

1) parallel projection must be turned OFF, otherwise the views are not 
linked.
2) time range of the data must be [0-1], otherwise timesteps are 
truncated to [0-1]
3) With a time-range of [0-1], the last frame never ends up at time=1, 
but at an earlier timestep. Looking in the source code, an easy fix is 
on line 565 of ./Servers/ServerManager/vtkSMComparativeViewProxy.cxx

changing the computation of the increment from

  double increment =  (this->TimeRange[1] - this->TimeRange[0])/
    (this->Dimensions[0]*this->Dimensions[1]);

to

  double increment =  (this->TimeRange[1] - this->TimeRange[0])/
    (this->Dimensions[0]*this->Dimensions[1] - 1.0);

fixes at least that issue. May we suggest to the developpers to apply 
this change, and see how issues 1) and 2) could be fixed.

This is with ParaView cvs of today.

cheers
Jean
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