Home > Regions & booleans

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Turn curves into filled regions and combine them with exact union, intersect, and difference.

A region is a closed, filled shape - the building block you union, subtract, and offset to compose a pattern. Locus keeps regions exact: when a boundary curves, it stays a true arc, not a chopped-up approximation.

There are three ways to make one.

• From points. Pick three or more points and Locus fills the polygon they enclose. If a corner has two or more real points stacked on the same spot, a chooser pops up so you pick which one that corner is: the same disambiguation used elsewhere for a coincident stack (see Points). Clicking back on your first corner closes the loop by position, not by which exact point object you picked, so the region still closes reliably even when its start and end resolve to different-but-coincident points.
• From enclosing edges. Select curves that already close a loop and turn them into a filled region. When the endpoints are almost touching, Locus welds them so the boundary closes cleanly (you'll get a short confirmation when it does).
• By filling an enclosed space. Reach for Fill (the paint-bucket) and click inside any area that curves already enclose. Locus traces the surrounding curves, cuts the boundary out of them, and hands you a real region: one that moves and updates with the geometry it was cut from, and deletes cleanly when you remove it. Fill works against straight segments, arcs, and circles, and also against infinite lines and rays - a triangle made of three lines, or two segments and a ray, each floods to a clean loop.
• By painting across several spaces. Paint Region is Fill with a drag instead of a click: sweep the cursor across the enclosed spaces you want and every one it crosses joins a single fill, cut from the surrounding curves. With a fill already selected, Shift-drag adds spaces to it and Alt-drag takes them back out.

The three boolean operations combine regions, and every result comes back as exact geometry - arcs stay arcs. This is Locus's own analytic boolean engine, so a circle-and-arc shape survives the operation instead of degrading into a many-sided polygon.

The same two regions under each operation: Union merges them into one shape, Intersect keeps only the area they share, and Difference returns A minus B. In each result panel the two inputs are ghosted so you can read what was kept.

• Union welds everything into one region: all the input merged into a single filled shape, holes and all.
• Intersect keeps only the area two shapes share.
• Difference subtracts: it returns the first shape minus the rest.

Intersect and Difference are list-aware, which makes clipping a whole pattern to one shape a single step.

• The A input is the subject: if it holds many separate regions, each one is operated on individually, so a list of ten shapes in gives up to ten shapes out.
• The B input is the tool: one shape that clips or subtracts from every subject.

So to trim a full field of motifs down to a border, feed the field into A and the border into B with Intersect. A single region in A behaves exactly like a plain two-shape boolean.

Offset grows or shrinks a region's boundary by a distance you set, reconciling the corners as sharp, rounded, chamfered, or left open. An offset of zero passes the shape through unchanged. Offset is how you turn a pattern outline into a finished band, and it pairs naturally with the boolean workflow above.

For rounding and bevelling corners, see the Fillet and Chamfer nodes.

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