vtkMergeDataObjectFilter does not propagate time.

[rchristie]

I've been using the time series reader with vtkDataObject to read pure time-varying field data to merge into a non time-varying dataset with vtkMergeDataObjectFilter. I've found it doesn't report the time steps and time range from the data object.

This can be solved by adding a RequestInformation() method that propagates time; this largely copied from vtkProbeFilter:

int vtkMergeDataObjectFilter::RequestInformation(
vtkInformation _vtkNotUsed(request),
vtkInformationVector *_inputVector,
vtkInformationVector *outputVector)
{
if (this->GetNumberOfInputConnections(1) > 0)
{
// get the info objects
vtkInformation *outInfo = outputVector->GetInformationObject(0);
vtkInformation *dataObjectInfo = inputVector[1]->GetInformationObject(0);
outInfo->CopyEntry(dataObjectInfo,
vtkStreamingDemandDrivenPipeline::TIME_STEPS());
outInfo->CopyEntry(dataObjectInfo,
vtkStreamingDemandDrivenPipeline::TIME_RANGE());
}
return 1;
}

Even though this works for my data, I'm unsatisfied by this code and have some questions:
What happens if the input is time-varying but the data object is not?
What happens if both are time-varying but with different time steps and range?
Are there standard methods for merging time information from two sources?