geop-lib-shell

This page is a reference to the crate; its rebuild is taught in Lecture 30 and offsets in Lecture 31.

Shelling, built directly rather than cut out by a boolean: shell hollows a solid of a NamedModel out to walls of one thickness, open where the given faces were. Every face kept is offset inward, a vertex moves to where the offsets of its faces meet, an edge to where the offsets of its two faces meet, and where a face is taken away a rim joins the outer side to the inner one. The inner side has exactly the solid’s topology, so nothing is intersected.

A sheet is shelled the same way: thicken turns it into a solid, a wall along each free edge, and offset_faces copies faces along their normals into a sheet of their own.

Others that rebuild a solid face by face (a draft, geop-ops-plastic) use its pieces: extended gives a surface room around a face, pcurve a coedge’s pcurve on a moved surface, and surface_missed checks that a curve built for an edge lies on its faces.

What it takes are models, faces and solids by id, and a Namer; the Shell operation of geop-ops-shell resolves a step’s references and calls it.