How can I change scalar value for points in structured grid data?

Hi there,

I'm really new to paraview and vtk and I'm trying to write a programable filter in paraview and it seems need vtk functions. I'm trying to modify the content of my structured data's point value (not xyz but a scalar value), however, it seems structuredGrid don't have any scalar value to give a point besides its coordinates? May I check what will be a better way to do this?

Thanks!