Projected Textures: An example using the new SketchUp v2021.1 functionality

copy_face_materials_2021.1.rb

# Copy face materials (front and back) from a source face to a target face.
# For v2021.1 and higher, any texture positioning and projection is copied.
# @param face1 [Sketchup::Face] the source face.
# @param face2 [Sketchup::Face] the target face.
# @return [Boolean] whether texture positioning was enabled during copy.
def copy_face_materials(face1, face2)
  # Test if the API is at or higher than 2021.1:
  positioning_enabled = face1.respond_to?(:texture_projected?)
  #
  frontside = true
  backside  = false
  reference = face1.vertices.first.position
  #
  for side in [frontside, backside]

    meth =( side ? :material : :back_material )
    matl = face1.send(meth)

    # Copy this side's material (might set to nil):
    face2.send("#{meth.to_s}=", matl)

    next unless positioning_enabled

    # If this side's material has a texture and is positioned:
    if matl.texture && face1.texture_positioned?(side)
      mapping = face.uv_tile_at(reference, side)
      if face1.texture_projected?(side)
        face2.position_material(
          matl, mapping, side, 
          face1.get_texture_projection(side)
        )
      else
        face2.position_material(matl, mapping, side)
      end
    end

  end # for side
  #
  return positioning_enabled
end