occt

OpenCascade is an open-source software development platform used for building 3D modeling and visualization applications. It provides a set of tools that allow developers to create complex geometric models and perform operations on them, such as Boolean operations, intersections, and extrusions.

OpenCascade is often used in the engineering, architecture, and manufacturing industries for designing and analyzing objects and structures.

This is a wrapper that enables using OpenCascade from Nim.

The site it is not maintained. Maybe in the future: Further documentation in occt.nim site

Example

The following has been done with occt.nim.

3d model viewer

How to install?

Right now I am only testing it in Linux (ArchLinux). You can install OpenCascade like:

ArchLinux:

$ yay -S opencascade

Ubuntu:

$ sudo apt install libocct-foundation-dev

In order to install the bindings:

$ nimble install https://github.com/mantielero/occt.nim

Status

Right now, a significant part of the library is wrapped. There are 75 packages already wrapped (in better or worst shape). For sure, there are much more functions wrapped than what you might need.

Most of the bindings are untested. On the other hand, they should work (or they should work with very little modification).

Wrapping the functions is the first step. Later you need more convenient functions that make the library more convenient to use (more "Nim-ish" -if that word exists-).

Library structure

The wrapped packages are located under src/wrapper.

In the folder src/lib, some functions are included in order to make easier dealing with OpenCascade.

I wanna help!

There are many things that can be done:

Using the library. This will help to detect issues. This is about populating the examples folder.
Improving the usability. Some examples on how to improve the usability can be found in src/lib/foundation/gp.nim or src/lib/foundation/iter.nim.
Adding easier API's like CadQuery or RepliCAD are proposing. An example is src/lib/sketcher/sketcher2d.nim. With that API you can do things like examples/api/sketcher2d_01.nim.
OCCTUtils: seems interesting as well. It could serve as inspiration also. See also https://techoverflow.net/category/opencascade/
If you wanna add a new package, here you can find some instructions. It is pretty straightforward.

License

I don't know much about licenses (any advise is wellcomed). My code is BSD, but you need to fulfill whatever OpenCascade license requires which is: GNU Lesser General Public License (LGPL) version 2.1.

How to add a new package

Create the new package folder. For example src/wrapper/pcdm.
Copy the files genGenerator.nim and ed.nim from src/wrapper/cdm into the new folder.
In genGenerator.nim modify the following lines:

let prefix = "CDM"
let packageName = "cdm"

The prefix indicate the starting string for the header files under /usr/include/opencascade.

The packageName is the name of the created folder.

Execute genGenerator:

nim c -r genGenerator

this will create a new file gen.nim and copy opencascade headers locally.

Execute gen.nim:

nim c -r gen

this will execute c2nim under the hood.

If all the headers were removed, then everything went fine. If not, you will have to play with gen.nim commenting parts of the headers in order to avoid c2nim failing.

Then we edit src/wrapper/pp.nim (not a beauty). Around line 650, you have something like:

let folder = "cdm"
let toolkit = "TKCDF"

comment those lines and add two similar lines with the name of the new folder and the name of the associated toolkit for the package. In this case:

#let folder = "cdm"
#let toolkit = "TKCDF"

let folder = "pcdm"
let toolkit = "TKCDF"

Execute it, by going into folder src/wrapper and then:

nim c -r pp

Notes: a. Fixing Iterator. Iterators are defined in ncollection_types. If you have something like:

StorageDataMapIteratorOfMapOfPers* = Iterator....

probably needs to be:

StorageDataMapIteratorOfMapOfPers* = NCollectionDataMapIterator....