How do I build OpenSim Creator 0.5.10 on Ubuntu 20.04?

[adamkewley]

Question ported from [email protected] . Details REDACTED because the original source was a private email.

Our group has used OpenSim already for a few years in human motion analysis, and I rather recently started to develop Bayesian estimation tools (non-linear Kalman filters) for inverse kinematics in OpenSim.

Your name and OpenSim Creator came up as I contacted Professor Ajay Seth, acquaintance of our collaborator REDACTED. I became very interested when I heard that OpenSim Creator is a C++-based GUI, since we have issues of generating custom interfaces for OpenSim core, most notably on the Java side (having no prior experience on using SWIG does not help).

I am writing you to ask for guidance on how to build OpenSim Creator. My primary OS is Windows 11 so I first followed the build instructions for Windows. The build script threw an error very early, stating, 'compiler is not able to compile a simple test program'. I could not find useful solutions so I decided to set up a virtual machine on Hyper-V and try the build instructions for Linux.

On a VM running Ubuntu 22.04.4 I got further. The OpenSim core and OpenSim gui build scripts executed without errors. OpenSim Creator build script (build_debian-buster.sh), however, throws an error when building the Oscar library. I will attach a screenshot to clarify.

After some googling, I infer this error is related to template aliases and how they are used in different C++ standards — that is, the syntax used in CircularBuffer.h would be ok in C++20 and later standards, but I think gcc uses C++17 as default. Could you please confirm which C++ standard one should use when building Oscar, and whether this needs to be explicitly specified for the compilers (or is this handled already in some build file and I have just missed that)?

I would appreciate any further tips on configuring the tools. I would be happy to work with and expand OpenSim Creator, but first I need to be able build the basic version.

[adamkewley]

Note to all readers: opensim-creator is not an API-stable library project. It's an application that only guarantees GUI stability. Therefore, you can probably throw something together using the code that's within a release (e.g. 0.5.10), but beware that future versions of OSC are permitted to entirely change large parts of the API.

You got very close! Your diagnosis is correct: it's a C++20 project. This means that you need to use a C++20 compiler when building the sources.

The way to do that on Ubuntu 20.04 is to build it with clang instead of gcc (or use a newer gcc). The way you customize which compiler a build script should use is to set the CC and CXX environment variables before configuring the project. So, for you, I'd remove the (configured with the wrong compiler) oscar build and then rebuild it with clang:

rm -rf osc-build && CC=clang CXX=clang++ ./scripts/build_debian-buster.sh

See: https://github.com/ComputationalBiomechanicsLab/opensim-creator/blob/0.5.11/.github/workflows/continuous-integration-workflow.yml#L53

You'll need to install clang++ on Ubuntu 20.04 or greater in order for this to work (apt-get install clang++). You can also try g++-12 (apt-get install g++-12; CC=gcc-12 CXX=g++-12), which can compile C++20. However, it isn't tested in CI (EDIT: changed since 0.5.12, which also builds via gcc), so there's sometimes some errors that get through whenever I haven't manually double-checked it.