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OCC beginner is missing something

Matteo's picture

Hello OCC experts,

I'm an assolute beginner with OCC and I'm trying to use it to see if it fits my needs. I'm working on Ubuntu-8.10 using the packages

- libopencascade6.2 (6.2-7ubuntu1)
- libopencascade-dev (6.2-7ubuntu1)
- opencascade-doc (6.2-7ubuntu1)
- opencascade-examples (6.2-7ubuntu1)
- opencascade-tools (6.2-7ubuntu1)

provided by my distrib (via aptitude).

Basically (for now), I'm interested in visualizing an object whose CAD data are in an existing STP file. I found an example which supposed to work with STP files at I tried, and it compiled and linked succesfully:

g++ -I/usr/include/opencascade -DHAVE_CONFIG_H -DHAVE_IOSTREAM -DHAVE_FSTREAM -DMAVE_LIMITS_H -lTKTopAlgo -lTKPrim -lTKFillet -lTKBO -lTKOffset -lTKSTEP -lTKXSBase main.cxx -o exe
main.cxx: In function 'int main()':
main.cxx:18: warning: deprecated conversion from string constant to 'char*'

But when I tried to launch the executable file, it didn't show anything. Am I missing something?

Thank you for your time,


Arthur Magill's picture

Hi Matteo,

Not an expert here, but I think I can point you in the right direction :-)

The example in the thread you linked only tests the reader - it doesn't try to display anything. If no error message appears, you have successfully compiled an OCC program that can read your STP file - so, progress of sorts!

Two ideas to get you started come to mind. You could have a look at the tutorial example shipped with OCC (the one that builds and displays a bottle). You could probably combine your basic STP reader with that fairly easily.

Alternatively, have a look at PythonOCC ( It's a set of Python wrappers around OCC. There are quite a few examples provided and the support, via the email list, is *very* good (thanks Thomas & Jelle). I can't remember, but there may already be a STP read/display example in there.

Good luck and let us know if you get it working,


Matteo's picture

Hi Arthur,

thank you for your suggestions.

Actually, looking at the MakeBottle tutorial is the first thing I tried to do, but, unfortunately, the "opencascade-examples" package provided by my distrib does not ship any of the tutorials that can be found in the source version of OCC.

At light of this fact, I removed Ubuntu's OCC packages from my PC and installed OCC sources with the usual combination

make install

executed from the OpenCASCADE6.3.0/ros directory (I got a failure during the make process, fixed as explained at

However, I'm still not able to run any of the demonstrations in the OpenCASCADE6.3.0/samples directory. As an example, when I try to execute the script to compile the code in OpenCASCADE6.3.0/samples/tutorial/src, I get the following error:

matt@isaac:/usr/src/OpenCASCADE6.3.0/samples/tutorial$ export CASROOT=/usr/src/OpenCASCADE6.3.0/ros/
matt@isaac:/usr/src/OpenCASCADE6.3.0/samples/tutorial$ sh
Executable "/usr/src/OpenCASCADE6.3.0/samples/tutorial/Linux/bin/Tutorial" not found.
Probably you don't compile the application. Execute "make".

What does it means? There is no "Makefile" in the OpenCASCADE6.3.0/samples/tutorial directory. Ideed, if try to type "make", I get:

matt@isaac:/usr/src/OpenCASCADE6.3.0/samples/tutorial$ make
make: *** No targets specified and no makefile found. Stop.

Where should I execute "make" then?

I get the same error also with the QT demo in OpenCASCADE6.3.0/samples/standard/qt. Maybe I skipped some critical step during the installation process?

Thank you for your time.


Arthur Magill's picture

Hi Matteo,

The tutorial is QT based - you should see a file called in the tutorial directory. Make sure you have the qt-devel libs installed, then run "qmake". That will generate a Makefile. You can then run make as-per-normal. Check inside the Linux/bin directory, where you should find Tutorial. The run it, use the script (it sets some env vars I think).

Good luck!


Matteo's picture

Hello Arthur,

I'm new both in OCC and in QT-based GUI, so I didn't know that I should have run the qmake command on Thank you!

I installed a lot of qt4* packages, and the following dev libraries:

- libqt4-dev
- libqt4-opengl-dev

and finally, after a make failure complaining of not finding the command /bin/lrelease (I fixed it with a symlink to /usr/bin/lrelease), I've been able to create the executable file for the tutorial.

However, when I launch it, I get an empty GUI with a lot of buttons (MNU_FILE, MNU_VIEW, MNU_HELP, MNU_NEW and MNU_ABOUT). I tried to click on MNU_NEW button to see if I would be able to visualize something, but the whole application crashed and the following message appeared on the shell:

matt@isaac:/usr/src/OpenCASCADE6.3.0/samples/tutorial$ ./Linux/bin/Tutorial
terminate called after throwing an instance of 'Aspect_GraphicDeviceDefinitionError'

The same issue occurred also with the IESample demo in OpenCASCADE6.3.0/samples/standard/qt. Any ideas?

Thank you for your valuable advices!


Matteo's picture

Ok, sorry.

Just a quick update. I forgot to run "" after the make command. I didn't specified the QTDIR and this is the reason for which I got the complain of not finding the command /bin/lrelease.

I exported QTDIR to /usr/share/qt4/ and now I get a nice --still empty-- GUI where buttons have labels. However, clicking on the "New" button to try to visualize something still leads to a crash of the whole application:

matt@isaac:/usr/src/OpenCASCADE6.3.0/samples/tutorial$ sh
terminate called after throwing an instance of 'Aspect_GraphicDeviceDefinitionError'

Thank you!


Arthur Magill's picture

You're close now. Have you set CASROOT? Did you set various env vars, by running

$ source $CASROOT/

? (if you don't have ksh installed, just change the first line to #!/bin/bash instead). You may have to edit this file, and, to find a sensible QTDIR (mine is /usr under Debian), TCL, etc. You sound like you know how to figure these out :-)

Matteo's picture

Hello Arthur,

your sentence "my QTDIR is /usr" made me rethink the whole setting I chose for the environment variables. So, I changed them to


launched and it did work! The demos are really impressive.

Thank you for your help.


Arthur Magill's picture

Excellent, glad it's working. Now you just have to write your STP reader ;-)


Bryan Bishop's picture

By the way, there are packages available for OCC 6.3.1 (you said you're using 6.2.7?). Try this:

sudo apt-key add opennovation.key
echo "deb jaunty main contrib non-free" | sudo tee -a /etc/apt/sources.list
sudo apt-get update

sudo apt-get install libopencascade-visualization-dev libopencascade-dev libopencascade-dev x11proto-core-dev libx11-dev libopencascade-visualization-dev libopencascade-ocaf-dev opencascade-wok opencascade-draw

Hope this helps. They seem to have debug output turned on though, so be mindful of that. They probably have to be recompiled if you want them to be quiet.