Merge Hole Output Modes

When Merge Overlapping Polygons creates shapes that contain holes, LinkCAD can emit the result in three different representations.

Use this page as the reference for the Draw generated holes using… option in the Merge dialog.

Modes

Mode	What geometry is emitted	Best for
Cut-lines in re-entrant polygons	One polygon per merged island, with bridge/cut-lines connecting each hole to the outer boundary	Workflows that require a single contour object and can accept bridge segments
Sliced simple polygons	Multiple simple polygons with no holes and no internal cut-lines	Downstream tools that reject re-entrant boundaries but can consume multiple polygons
Extract holes as polygons	Hole regions emitted as standalone polygons, separate from the outer shape	Pipelines that represent holes as explicit independent polygons

Visual Comparison

Important: In these illustrations, visible gaps and separation are intentionally exaggerated for clarity. In real outputs (for example, photomask data), cut-lines and sliced boundaries are superimposed and typically not visible as open gaps.

Cut-lines in re-entrant polygons

The hole is linked to the outer contour by a cut-line, producing a single re-entrant polygon boundary.

Sliced simple polygons

The shape is split into multiple simple polygons so no cut-line is needed.

Extract holes as polygons

The outer region and the hole are emitted as separate polygons. Depending on the target format and renderer, these independent polygons may overlap in display or require additional post-processing to reconstruct hole semantics.

Choosing a Mode

• Use Cut-lines in re-entrant polygons when you want a single merged shape per island.
• Use Sliced simple polygons when your target toolchain requires simple (non-re-entrant) polygons.
• Use Extract holes as polygons when your pipeline explicitly manages hole regions as separate objects.

See also: Merge Overlapping Polygons, Extract Holes, and De-embed Polygons.