This page is under construction. This should eventually gather documentation for all keys used by VTK pipeline
- SDDP: vtkStreamingDemandDrivenPipeline
- DDP : vtkDemandDrivenPipeline
Fast Path Related Keys
Fast path mechanism is designed for providing some means for quickly accessing the data values associated with a cell or point over time instead of having to request the full dataset for each timestep and the pick the cell or point of interest.
- A boolean (0, 1) value set in output information by a vtkAlgorithm subclass during RequestInformation() pass to indicate that the algorithm supports fast path.
- All the other keys are set by consumers in RequestUpdateExtent() to request a particular cell or point from the input.
SDDP:: FAST_PATH_OBJECT_TYPE() [vtkInformationStringKey]
- Set by consumer in input information during RequestUpdateExtent() pass to indicate the type of the item being requested i.e. "CELL" or "POINT". "Face"/"Edge" are mentioned, but not really supported.
SDDP:: FAST_PATH_ID_TYPE() [vtkInformationStringKey]
- Used to indicate the index type i.e. GLOBAL ID or VTK id (local id). vtkExodusIIReader (the only reader supporting fast path) only supports GLOBAL ids.
- The actual id being requested.
- When the reader finds all the 3 keys in the output information in RequestData() it should information about the requested cell/point in field data of the output. Simply put, vtkExodusIIReader simply adds arrays named "<ArrayName>OverTime" associated with each point (or cell) array for the point (or cell) and with number of tuples == number of timesteps in the dataset and values of the tuples == the value for the array at that point (or cell) for the corresponding timestep.
Currently used by:
Note that the these keys are not propagated across filters. So if you put any other filter between vtkExodusIIReader and vtkExtractArraysOverTime, fast path cannot be used.