1f5e0f6494
Historically, `App::Document::recompute()` ran entirely on the **main**
(GUI) thread and directly emitted `signalBeforeRecompute()`.
* Add-ons like **Assembly3** and others depend on that signal for
setup/teardown hooks before any recompute work begins.
* After offloading `recompute()` into a background worker thread to keep
the UI responsive, calling `signalBeforeRecompute()` directly from the
worker would break thread-affinity rules and silently break
compatibility with those add-ons.
**Solution**
1. **Introduce a generic hook** (`PreRecomputeHook`) in
**App::Document**:
* A `std::function<void()>` that, if set, is invoked at the very
start of `recompute()`.
* Core code stays Qt-free—only knows to call a callback if one
exists.
2. **Wire up the hook in `Gui::Document`**:
* In the GUI wrapper’s constructor, install a hook that calls
`callSignalBeforeRecompute()`.
* `callSignalBeforeRecompute()` uses `QMetaObject::invokeMethod(...,
Qt::BlockingQueuedConnection)` to enqueue `signalBeforeRecompute()` on
the GUI thread and **block** the worker until it completes.
* If already on the GUI thread, it simply calls the signal directly.
3. **Maintain add-on compatibility**:
* From the add-on’s perspective nothing changes—they still receive
`signalBeforeRecompute()` on the main thread before any recompute work.
* Internally, the recompute body now runs on a worker thread,
improving UI responsiveness without breaking existing hooks.
**Result**
* **Recompute** remains fully backward-compatible for add-ons like
Assembly3.
* **UI thread** still handles all GUI-related signaling.
* **Worker thread** performs the actual heavy lifting, unblocked only
once the GUI is primed and all pre-recompute signals have been
delivered.
Your own 3D parametric modeler
Website • Documentation • Forum • Bug tracker • Git repository • Blog
Overview
-
Freedom to build what you want FreeCAD is an open-source parametric 3D modeler made primarily to design real-life objects of any size. Parametric modeling allows you to easily modify your design by going back into your model history to change its parameters.
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Create 3D from 2D and back FreeCAD lets you to sketch geometry constrained 2D shapes and use them as a base to build other objects. It contains many components to adjust dimensions or extract design details from 3D models to create high quality production-ready drawings.
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Designed for your needs FreeCAD is designed to fit a wide range of uses including product design, mechanical engineering and architecture, whether you are a hobbyist, programmer, experienced CAD user, student or teacher.
-
Cross platform FreeCAD runs on Windows, macOS and Linux operating systems.
-
Underlying technology
- OpenCASCADE A powerful geometry kernel, the most important component of FreeCAD
- Coin3D library Open Inventor-compliant 3D scene representation model
- Python FreeCAD offers a broad Python API
- Qt Graphical user interface built with Qt
Installing
Precompiled packages for stable releases are available for Windows, macOS and Linux on the Releases page.
On most Linux distributions, FreeCAD is also directly installable from the software center application.
For development releases visit the weekly-builds page.
Other options are described on the wiki Download page.
Compiling
FreeCAD requires several dependencies to correctly compile for development and production builds. The following pages contain updated build instructions for their respective platforms:
Reporting Issues
To report an issue please:
- Consider posting to the Forum, Discord channel, or Reddit to verify the issue;
- Search the existing issues for potential duplicates;
- Use the most updated stable or development versions of FreeCAD;
- Post version info from
Help > About FreeCAD > Copy to clipboard; - Restart FreeCAD in safe mode
Help > Restart in safe modeand try to reproduce the issue again. If the issue is resolved it can be fixed by deleting the FreeCAD config files. - Start recording a macro
Macro > Macro recording...and repeat all steps. Stop recording after the issue occurs and upload the saved macro or copy the macro code in the issue; - Post a Step-By-Step explanation on how to recreate the issue;
- Upload an example file (FCStd as ZIP file) to demonstrate the problem;
For more details see:
Note
The FPA offers developers the opportunity to apply for a grant to work on projects of their choosing. Check jobs and funding to know more.
Usage & Getting Help
The FreeCAD wiki contains documentation on general FreeCAD usage, Python scripting, and development. View these pages for more information:
The FreeCAD forum is a great place to find help and solve specific problems when learning to use FreeCAD.
This project receives generous infrastructure support from
and KiCad Services Corp.