Though I did pointed to @David_Tschumperle about a tutorial for Cartesian Transform, I decided to bring attention to this website, which can provide inspiration for new filters:
Main Source: https://screamingbrainstudios.com/
Some collection of ideas for new filters: Textures with GIMP - Screaming Brain Studios - Free Game Assets
Bump Map or Lighting Effects is not something G’MIC has, but it would sure be nice to have those. Construction Material Texture has some elements of the above link.