C = union (A, B, …) takes any number of solid.Shape objects and combines them in one operation, which is several times faster than combining them a pair at a time. Faces that end up in one plane and edges that end up on one line are merged, so the union of two blocks that share a face reads as one block of six faces. Empty shapes add nothing, and the union of a single shape is that shape.

Each solid of the result takes the colour of the first coloured solid it came from, as solid.Shape.Colour describes.

 ## Two blocks side by side become one block
 A = solid.box (10, 10, 10);
 B = translate (solid.box (10, 10, 10), [10, 0, 0]);
 numfaces (union (A, B))
 ⇒ 6

See also: solid.Shape.subtract, solid.Shape.intersect

Source Code: solid.Shape