Finding active section planes in a scene

[DanRathbun]

@chris.bassett25

What I stumped on, is finding away to search for active section planes without activating the scene.

Good news, SketchUp 2026.0 has implemented:

• Sketchup::Page#active_section_planes()

So going forward we no longer need to transition to a page (or each page) to find which of the section planes are active.

---

With regard to API tracker issue # 25
See what scenes a section is used in · Issue #25 · SketchUp/api-issue-tracker

# See what scene pages where a section is active. (SU2026+)
#
# @return [Array<Sketchup::Page>] The list of scene pages that the given
#  SectionPlane is active on, or empty if the section is unused on any page.
def pages_active_on(section)
  unless section.is_a?(Sketchup::SectionPlane)
    fail(TypeError,"SectionPlane expected for <#{section.class}> argument.",caller)
  end
  section.model.pages.select do |page|
    page.active_section_planes.include?(section)
  end
end

@ene_su Does this snippet now satisfy tracker issue #25 ?
I.e., using page.active_section_planes.include?(section) within a select filter block upon the pages collection.

---

@chris.bassett25

I’m writing a script to delete unused section planes as an aid to working with large models and drawing sets.

And in keeping with this new API feature, the SketchUp Extensibility Team has released an Example extension to purge unused section planes. (requires SketchUp 2026 or higher.)

See:

Purge Unused Section Planes

New team extension is out today This extension lets you remove section planes not currently used by a scene. This allows you to quickly remove any temporary section planes you use to see what you are working on, without risking losing section planes carefully set up for use in Layout to generate drawings. This extension also serves as a code example for the new scene section plane API released in SketchUp 2026.0. SketchUp 2026.0 required.