🔹 Editable Poly – Border Selection & Capping 🔹

Now that we've covered polygon selection, let’s dive into border selection—a tool used mainly for working with open edges and gaps in geometry.

1️⃣ What is Border Selection?

A border is a selection of open edges that form a continuous loop.

• Example: If you delete a polygon from an object, the surrounding edges form a border.
• Use Case: Borders are useful when modeling objects with holes, cutouts, or gaps.

2️⃣ Selecting Borders

1. Switch to Border Mode (Shortcut: 3 in Editable Poly).
2. Click on any open edge → The entire border loop will be selected.
3. Shift+Click → Add more border selections.

3️⃣ How to Cap Borders (Fill Gaps)

✅ Using Cap to Close a Hole

• Select the border (the open loop).
• Go to Edit Borders → Click Cap.
• This creates a single polygon covering the hole.

✅ Fixing Geometry After Capping

• The cap may not have clean topology.
• Use Alt+C (Cut Tool) to manually add supporting edges.
• Adjust smoothing groups to prevent shading issues.

4️⃣ Other Useful Border Tools

🔹 Bridge Tool (Connecting Two Borders)

• If two separate open borders need to be connected:
  1. Select both borders.
  2. Click Bridge → Creates a polygon bridge between them.

🔹 Extrude Borders (To Extend Geometry)

• Select a border → Use Extrude to create a new extrusion.
• Useful for expanding an object’s shape without creating new polygons manually.

5️⃣ Best Practices for Capping Borders

✅ Always check topology after capping (use Alt+C to refine).
✅ Avoid n-gons (caps may create non-quads).
✅ Use Bridge instead of Cap when connecting gaps.
✅ After capping, apply smoothing groups for clean shading.