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ifcGears : Open Source IFC Library/Framework & Viewer

ifcGears (

This is a C++ Open Source library, providing a framework to generate IFC reader/writer classes from the Express files.

In addition, there is an IFC Viewer program, using OpenSceneGraph or OSG ( and Nokia Qt SDK (

Compilation Issues

I was able (after some serious struggle) to compile the ifcGears library and the ifcGearsViewer on OSX.
It uses the CMake build system ( which has support for OSG. But the GUI-version of CMake on OSX does not properly generate all settings, as it seems to miss the environment variables somehow. When generating the XCode project or the Makefiles using cmake from the command line, things run smoother.

Anyway, if you use the graphical CMake, you have to ensure that all libraries are found. I have only used the release-versions.

With the OPT_VIEWER you can optionally enable the generation of the IFC Viewer too, but you need OpenSceneGraph installed properly (which was also a bit of a problem on OSX, but I'll skip that in this post). I used version 3.0.1. In addition, you also need Qt available (qmake etc...). I used version 4.7.

All was compiled for 64-bit (x86_64) for Intel and using Cocoa (native) instead of Carbon (deprecated), but it should be possible to make 32-bit versions for PPC and Intel too.

With all of that into place, I was able to compile the library and the viewer.

The red commands are probably due to the IFC-version used when exporting the model from ArchiCAD. I am not worrying too much here, as I have to test more.

I see no Windows or Doors and some walls are apparently not visible. When trying a single wall with a door and a window, the openings got hidden beneath the closed wall geometry, so more work seems to be required.


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