08 How to use Polygroup Edit and Subdivide in Unreal Engine 5 6

Session 8 Summary – Model Menu: Polygroup Edit & Subdivide Tools

🔹 Project Setup

• New project: polygroup_practice.

• Created a new level with atmospheric lighting (Sky Light, Directional Light, Sky Atmosphere, Cloud, Fog).

• Switched to Modeling Mode (Shift + 5).

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🧩 Polygroup Edit Tools

🔸 Selection Filters

• Choose to edit vertices, edges, or faces.

• Use edge loop selection for efficient edge operations.

🔸 Core Tools

• Extrude: Pulls geometry outward (supports normal-based and even extrusion).

• Offset: Offsets faces, especially at corners (90°), with even spacing options.

• Push/Pull: Moves geometry with deletion or flattening effect (unlike Extrude).

• Inset / Outset: Creates inner or outer face boundaries for further modeling.

• Bevel: Adds curvature to edges by defining bevel width and subdivisions (curve effect).

• Delete Faces: Removes selected faces (can lead to flipped normals).

• Flip Normals: Changes the direction of face normals for rendering visibility.

• Fill Hole: Closes any open polygon loops or gaps.

• Insert Edge Loop: Adds edge loops to control shape and support subdivisions.

• Cut Faces: Manually slice geometry for custom face shapes.

• Duplicate: Clones a face, often used to construct new sections like roofs.

• Collapse: Collapses all selected vertices into one central vertex.

• Weld: Merges selected vertices into one.

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🏛 Modeling Exercise Examples

• Structure with Pillars: Used cut face and push/pull to design four-pillar base and a roof with dome effect.

• Flipped Normals: Demonstrated face direction effects on visibility.

• Gopuram-like Roof: Created with extrude + collapse + weld for vertex merging.

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🌀 Subdivision Tools

🔸 Types of Subdivision

• Catmull-Clark:

  • Smooths and rounds geometry heavily.

  • Ideal for organic forms but distorts hard edges.

  • Based on mathematical interpolation of edge loops.

• Bilinear:

  • Maintains shape better with even face division.

  • Ideal for mechanical or hard-surface models.

• Loop Subdivision:

  • Triangle-based subdivision for specific mesh structures (less commonly used).

🔸 Subdivision Control with Edge Loops

• Added supporting edge loops to preserve geometry shape during subdivision.

• Example: Created a coffee cup model with clean bevels and inside extrusion.

🔸 Demo Comparison

• Created three labeled cubes (sm_cap, sm_bilinear, sm_catmul) to visualize:

  • Catmull-Clark (spherical result),

  • Bilinear (retains boxy shape),

  • Loop (optimized triangle pattern).

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✅ Conclusion

• Covered entire Polygroup Edit toolset and three types of Subdivide operations.

• Prepped foundation for next session focusing on Boolean operations and more Model menu components.