Context Cad

Experimental front end for cadquery.

import contextcad

with contextcad.workbench() as bench:
    with bench.build3d() as b:
        box = bench.box(5, 5, 5)
        top = box.face(">Z")
        with top.build3d():
            box_with_hole = box.hole(1)

would be analogous to

import cadquery as cq
box_with_hole = (
    cq.Workplane("front")
    .box(5, 5, 5)
    .faces(">Z)
    .hole(1)
)

Introduction

The idea here is the api is a roughly a "direct" api. Meaning when it comes to building an object that is composed of sub-objects, those sub-objects must be explicity referenced. Additionally every object is immutable.

i.e (to define a union of two solids)

new_shape = a_shape + some_other_shape

(a_shape and some_other_shape remain unchanged)

The difference between this and a pure "direct" API, is that:

1. There are different contexts which manage different tools you have access to.
2. Each context lives on a plane, which sets the local coordinate system.
3. These contexts automatically manage the GUI CAD view.

Contexts

There are different contexts which supply different APIs.

build3d

The build3d context is activated from the current context via

with c.build3d() as c:
    # some stuff here

In general it is the context to work with solids.

• Provides methods like c.box(), c.sphere()
• Solids are only allowed to be union'd, insected, etc... in this context
• Shapes are only allowed to be extruded in this context

build2d

The shapes workbench is activated from the current context via

with c.build2d() as c:
    # some stuff here

• Provides methods like c.circle(), c.rect()
• lines/wires must be "closed" in this context

lines_workbench

haven't quite figured this out but the idea here is this is where you do constraint based sketching

assembly_workbench (to-do)

where you create assemblies

Control Flow

In cadquery you can have multiple veritices/edges/faces selected and create objects at each point simultaneously i.e

import cadquery as cq

box_with_spheres_on_faces = (
    cq.Workplane("front")
    .box(5, 5, 5)
    .faces()
    .sphere(1)
)

To reduce complexity, in contextcad this would instead be done with a for loop. Something like

import contextcad

with contextcad.workbench() as bench:
    with bench.build3d() as b:
        box = b.box(5, 5, 5)
        box_with_spheres = box
        for face in box.faces():
            with face.build3d() as b:  # plane is automatically set to the face's plane
                box_with_spheres += bench.sphere(1)

with build1d() as ctx:
    l = ctx.start(0, 0).line(5, 0)
    l += l.angle(90).line(5)

with build1d() as ctx:
    ctx.line(0,3).angle(30).go().until(4)
    ctx.go().parallel_to().go().until(4)