UV texture coordinate math expressions in 'Make Parametric Grid Mesh' node

(Created on behalf of @unicode from Make Parametric Grid Mesh node doesn’t conform to documentation.)

Add input ports U Expression and V Expression that allow specifying arbitrary UV texture mappings independent of the mesh’s shape in XYZ space.

Examples of how this would be useful (details here):

  • scrolling an image around a curved surface
  • wrapping world-map images of various projections onto a sphere