Booleans

Example A gear cut by its rack: one subtraction per position Example A bone scaffold: some 6000 struts united Example A motor lamination glued into its regions Example The moving sofa as one intersection

Faces combine with + (union), - (difference) and * (intersection), and lists of faces with px.Unify, px.Subtract and px.Intersect, which run on all cores. Every edge is cut where it meets an edge of the other operand. After that, each piece lies wholly inside, wholly outside or on the boundary of the other operand, so one test at its midpoint decides whether it stays. Where edges meet, they share one bit-exact vertex, so no gap remains between them, and the areas agree with their formulas up to rounding. Lines, arcs and full circles stay exact, and the result is a shape of clean faces, ready for the next operation.

px.Glue keeps the parts as regions that share their common edges, which is what a mesher needs for several materials. See Faces, shapes and compounds for gluing faces. Split and Trim cut faces and wires along any curve.

In this section

Two facesUnion, difference and intersection of two faces, keeping names and colors.

Many faces at onceUnify, Subtract and Intersect on lists, as a balanced tree on all cores.

Faces and wiresWires united and glued, as in a truss built from its member center lines.

Splitting and trimmingA face cut along any curve, from segments to trimmed blanks and punched holes.

Traces and padsOffsets of paths, round pads and drills, with every edge named after its net.

Everything at a glance

Two faces	a + b, a - b, a * b, a += b, a -= b, a *= b
Many faces	px.Unify(faces), px.Intersect(faces), px.Subtract([first, *others]), on all cores
Wires	wire + wire unites wires; face + wire raises a TypeError.
Glue	px.Glue(parts) cuts faces and wires against each other. Faces that touch share their edges. Two overlapping parts give three faces, each part alone and the overlap, which takes the first part’s properties. A part entirely inside another keeps its own region and properties, and a wire through a face splits it.
Splitting	Split(cutter), Trim(cutter, keep_closest_to=, remove_closest_to=, keep_largest=, keep_smallest=, keep_left=, keep_right=)