OpenCASCADE/fr

Description
OpenCASCADE Technology, OCC ou OCCT pour faire court, est une collection de bibliothèques C ++ qui constituent ensemble un noyau professionnel de conception assistée par ordinateur (CAO) pour la modélisation 2D et 3D objets et la construction d'outils spécialisés pour la fabrication, la simulation ou la visualisation. OpenCASCADE est le cœur des fonctionnalités géométriques de FreeCAD.

Les classes géométriques d'OCCT sont pour la plupart implémentées et rendues disponibles dans FreeCAD via l'atelier Part, dont dépendent la plupart des autres ateliers. Il fournit également des fonctions internes pour lire et écrire différents formats de fichiers comme STEP et IGES, et pour effectuer des projections 2D, qui peuvent être utilisées pour créer des dessins techniques dans l'atelier TechDraw.



OpenCASCADE ne doit pas être confondu avec OpenSCAD, qui est un autre projet open source pour construire des modèles 3D et qui est accessible via l'atelier OpenSCAD.

OpenCASCADE est un logiciel libre régi par les termes de la GNU Lesser General Public License (LGPL) version 2.1 avec une exception supplémentaire.

Installation
OpenCASCADE is a core component of FreeCAD, so if you get FreeCAD from one of the links in the Download page, you will have it installed, and no further installation is necessary.

However, if you would like to develop applications that use OCCT, or would like to contribute C++ code to FreeCAD, then you need to install the development files of OCCT. In this case, the procedure is explained in Compiling for each of the main systems, Linux, Windows, and MacOS.

Community edition
A "community edition" of OpenCASCADE, abbreviated OCE, was released in 2011, based on the official OpenCASCADE sources (OCCT) of version 6.5. In theory the community edition OCE should be compatible with the main version OCCT in most aspects, while having some additional code contributed by the community.

However, this alternative distribution stopped active development around 2017, and lagged behind the main version in terms of features and bug fixes. For this reason, since FreeCAD v0.17, FreeCAD is compiled exclusively with OCCT, and OCE is not tested.

In some older Linux distributions, FreeCAD is compiled against OCE 0.18, equivalent to OCCT 6.9.x, causing various issues that have been solved already in the main OCCT 7.x releases. If this is the case, try removing OCE, and installing OCCT instead. If this is not possible, use the AppImage to get a modern FreeCAD with an updated OCCT version.

History
The Cas.CADE geometric kernel was originally closed source, but it became open source under its current name around the year 2000. Shortly after, the FreeCAD project was started, with the oldest files being dated to January 2001. Read more in History.

OpenCASCADE version 6.6 and earlier were governed by its own "OCCT public license", which made it not entirely "free software". This was solved with the release of OCCT 6.7 (2013), when it adopted the LGPL2 license.

Related

 * Main website, opencascade.com
 * Development portal, dev.opencascade.org
 * OpenCASCADE Technology (OCCT), latest release
 * Glossary, Open CASCADE
 * Open Cascade Technology on Wikipedia
 * OpenCASCADE community edition (OCE), repository