VTK 9.6.0 has a weird change behavior when it comes to the legacy file format: The data type for OFFSETS and CONNECTIVITY of POLYDATA is vtktypeint64 after creation (using the Python bindings) but changes to long when saving+reading to VTKHDF. When writing without the detour via VTKHDF, the file has a mixture of C-types (double) and VTK-types (vtktypeint64), with the 9.6.0 change this is more consistent.
My understanding is that the VTK-specific types such as vtktypeint64 are fixed while long etc. can differ between C libraries/operating systems (see, e.g., https://stackoverflow.com/questions/63938192), so VTK-types seem to be the better choice.
Simple Legacy Formats - VTK documentation does not mention vtktypeint64 as a valid dataType. But it also states that the current version is 3.0 while VTK 9.5.2 and 9.6.0 write version 5.1. The link in VTK Legacy File Format Specification does not work anymore.
My questions would be
- Which datatypes are supported?
- Is there a preferred variant, e.g.
vtktypeint64orlong? - Can I contribute to the documentation?