SUBTRACT — Subtract

Subtracts some solids from another.

Command: SUBTRACT · Global name: _SUBTRACT · Alias: SU
Ribbon: Home › Modify

Subtracts some solids from another (boolean subtraction), like AutoCAD's SUBTRACT. Between polyhedra it is computed by an in-house BSP modeler (pure Rust), exact even with coplanar faces.

Usage

Type SUBTRACT or click it in the ribbon.
Select the base solid (to subtract from) and press Enter.

Select the solid to subtract from (or the base and then the ones to subtract) and press Enter:

Select the solids to subtract from it (one or more) and press Enter.

Select the solids to subtract and press Enter:

Shortcut: if in step 2 you select two or more solids and press Enter, the first one selected is the base and the rest are subtracted from it (with a window, the order is the drawing order: the oldest first). The same with a pre-selection.

The result keeps the base's properties (layer, color, linetype, material…), not the current ones.

Notes

Between polyhedra (planar-faced solids) the result is exact, also with coplanar faces (a tool flush with the top, the bottom or a facade, a through hole) and when subtracting several tools at once (they are subtracted one by one): AutoCAD audits it with no errors and MASSPROP reports the exact volume. The result can be subtracted from again.
A face with a hole (e.g. the top pierced by an opening) is stored split into several planar faces, so seam lines show; the geometry and the volume are exact.
Solids with curved faces are not yet supported in booleans; they come in a later phase.
See also UNION, INTERSECT, EXTRUDE and REVOLVE.