Add vtk threshold point

[finetjul]

Context

Add vtkThresholdPoints filter.

Results

A new filter with an example are added.

Changes

• Documentation and TypeScript definitions were updated to match those changes

PR and Code Checklist

• semantic-release commit messages
• Run npm run reformat to have correctly formatted code

Testing

• This change adds or fixes unit tests
• Tested environment:
  • vtk.js: master
  • OS: Windows
  • Browser: Chrome

[finetjul]

@floryst @jourdain I was surprised to have to shallow copy.
If I simply do outputData[0] = input, then the shader may not refresh.
This no-refresh happens when the threshold filter has previously generated a new ouput polydata and now it simply returns an old polydata. There must be some kind of time stamp issue. I'm not sure if that should be fixed instead in the mapper. WDYT ?

[floryst]

It's probably b/c input.getMTime() is older than output.getMTime() at that point, so there's probably a shouldUpdate flag set to false in the vtk algorithm macro. outputData[0] = input would probably work if input.modified() was called as well, but that's probably undesirable, so shallowCopy seems fine to me.

[floryst]

Are you planning on adding typescript definitions as well?

[finetjul]

Are you planning on adding typescript definitions as well?

I was not planning to because I do not use typescript. Shall we make it mandatory for new contributions ?

[floryst]

I was not planning to because I do not use typescript. Shall we make it mandatory for new contributions ?

It's a good idea to do so nowadays, especially since vtk.js is ingested by typescript projects.