Round Corners replaces sharp corners with circular fillets of a chosen radius, with a tangent join on both sides so the curves flow smoothly into the arc. Line corners, curve corners and mixed corners are handled, for both TrueType (quadratic) and PostScript (cubic) outlines.

Select Round Corners from the Glyph menu for a one-off with its own undo, or use the Outlines - Round Corners step of the Glyph Transformer to round many glyphs at once. Rounding follows your selection: with contours selected only those are rounded, with on-curve points selected only those corners, and with nothing selected the whole glyph.

Settings

•Radius - the radius of the fillet, in font units. Default 20.

•Corners - Outer rounds the corners on the outside of the strokes (and the matching corners inside counters where the fill turns back on itself), Inner rounds the corners of the counters, Both rounds all of them. Default Outer.

•Max angle - corners flatter than this angle are left alone, so gentle, near-straight nodes stay as they are and only real corners are rounded. Default 170 degrees.

•Absorb short segments - a near-straight point on a segment shorter than the radius would only let the corner next to it round to a tiny fillet; with this option such points are removed so the corner rounds to the full radius.

Variable fonts

On a font with several masters the corners are planned once on the default master, and the same nodes and segment counts are applied to every master, so the masters stay compatible and keep interpolating. A corner that is too shallow to round on some master keeps its point count there.