Metaballs

Metaballs remain editable source objects until explicit conversion. Previewing or saving them does not add ordinary contour points. Choose the paired-circle tool to place and move centers; use the inspector for position, Radius, Strength, and Threshold. Centers in a group blend together, while Start a new group prepares an independent group.

Use Groups to cubic or Glyph to cubic in the inspector or Path menu to create ordinary outlines. The overview can convert a font’s current source as one undoable batch. Convert before using an external compiler that does not understand Runebender’s metaball metadata.

For a separate output UFO, run:

runebender collapse-metaballs Source.ufo --out Cubic.ufo

The destination must not exist, and the input is not overwritten. --resolution controls field sampling and --accuracy controls curve fitting. Conversion prepares the result before publishing it and reports a failure rather than replacing an unresolved shape.

Metaball metadata uses the versioned com.runebender.metaballs glyph-lib key. The outline engine locates the field boundary, extrema, and curvature features, then uses img2bez for constrained cubic fitting. This preserves type-design structure such as extrema and on-axis handles in the converted contour.