Blender LoopTools Circle on Quad Face Loop

The Circle operator in Blender's LoopTools add-on rearranges selected vertices into a smooth, circular arrangement while preserving the mesh's existing topology. When applied to a quad face loop, it transforms the geometric shape of the quad strip into a circular ring or cylinder-like cross-section by evenly distributing the inner and outer vertices around a central point without altering the underlying four-sided face structure.

Geometric Redistribution

When you run the Circle operator on a selected loop of quad faces, Blender calculates a center point based on the selection and projects the boundary vertices into concentric circles. The vertices are spaced at equal angular intervals, transforming irregular or rectangular quad layouts into a clean, uniform radial pattern.

Topology Preservation

The Circle tool only alters the spatial coordinates (X, Y, Z positions) of the vertices. It does not delete, merge, or add any geometry. The quad faces remain intact, retaining their four-sided structure and edge flow, which ensures that subsequent subdivision surface modifiers and edge loops function predictably.

Handling Closed vs. Open Quad Loops

  • Closed Quad Loops: If the selected face loop forms a complete, unbroken ring, the tool reshapes the geometry into a flat circular washer, a circular hole, or a round tubular section depending on the orientation of the mesh.
  • Open Quad Strips: If the face loop has open ends, the tool bends the strip along a circular arc based on the angle and position of the selection endpoints.

Key Operator Settings

After applying the Circle operator, several parameters in the Operator panel adjust how the quad loop is transformed:

  • Fit (Inside / Best Fit): Determines whether the circle is sized to fit within the existing selection bounds or adjusted to the best mathematical average.
  • Radius: Allows manual specification of the exact circle radius.
  • Flatten: When enabled, projects all vertices onto a single flat 2D plane. When disabled, vertices maintain their relative height along the normal axis while still forming a circle from a top-down perspective.
  • Angle: Rotates the alignment of the vertices around the calculated center to control the twisting of the quad strip.
  • Regular: Distributes the vertices at strictly equal distances from one another along the perimeter.