Boolean operations on 2D sketches?

[paulftw]

I've checked the API docs but there seems to be no way to intersect rectangle and a circle for example.
This would be super useful when preparing a sketch for extrusion, adding NEMA mounting holes, etc.

What is the best way to implement this, apart from extruding each sketch and using 3D booleans?

I also really need positive & negative offset but that's probably a separate feature request.

[paulftw]

Answering my own question: BlueprintSketcher is pretty much a drop-in replacement of the basic sketcher, intersectBlueprints and fuseBlueprints can be used on its results.

Still trying to figure out an effective offset implementation

[raydeleu]

Did you check the new drawing API? If I remember well, the author of Replicad mentioned that the drawing API was created to allow boolean operations that are not possible with Sketches. See discussion on "drawing API".

I edit this on my phone, I can give you more details later.

[sgenoud]

The intersect is missing for Drawings! I have created an issue to implement it.

The Blueprint is a lower level abstraction than the Drawing that does not easily take care of edge cases where there are discontinuities (or holes). I need to wrap the intersectBlueprint logic so that any two Drawings can be intersected together.

[paulftw]

thanks @raydeleu just found the drawing thread. It does look useful and approachable, will check it out for sure.

I was so happy when I discovered Blueprint and most of my experiments worked out of the box, now I wonder if I should start over with Drawing 😉
As a new user I'm finding it hard to grasp the difference between Blueprint, Blueprints, CompoundBlueprint, (Compound?)Sketch(er?), Drawing and DrawingPen. but that's something that can be cleaned up later as the project matures.

[sgenoud]

The aim of the Drawing API is actually to cleanup the blueprint complexity. A drawing is either a Blueprint a Blueprints or a CompoundBlueprint. It then handles all the mess with this API (i.e. what happens when you try to fuse a Blueprint with a CompoundBlueprint.

All of this is hidden if you use draw do a bunch of edits on it and then you finish with a done (or close) and it creates a Drawing that you can do a bunch of things on.

Unless you are trying to do some lower level things, you don't need to worry about anything else.

Note that the Sketcher should disappear if we see that the draw API works well.

[paulftw]

@sgenoud you're doing a great job and I really appreciate your work!

not trying to spam you with features I might probably need some day, I'm sure you are already getting to many of those, but once intersect, union and difference are covered it'd be cool to consider inward/outward expansions and convex hulls - something I've personally needed in the past two weeks.

Those functions are notable omissions from what openscad & jscad offer. Supporting them will make a transition to replicad easier.

(I did check how cadquery is doing convex hull and seems like they wrote the algorithm from scratch in python, so probably OCCT doesn't have a ready-to-use implementation).

There's also minkowski sum, but my non-scientific research into real-world openscad shows that regular people never heard of it.