adOCCT: Algorithmic Differentiation of the Open CASCADE Technology modeling kernel

Algorithmic Differentiation (AD) is applied to Open CASCADE Technology (OCCT) in order to enable the computation of the so-called geometric sensitivities (e.g., derivatives of surface nodes with respect to its design parameters such as control points). The differentiated OCCT variant, named adOCCT, is developed by integrating the AD tool ADOL-C (Automatic Differentiation by Overloading in C++) into its source-code.

License

adOCCT is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License version 2.1 as published by the Free Software Foundation, with a special exception defined in the file OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in the adOCCT distribution for the complete text of the license.

Note: adOCCT is provided on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND. The entire risk related to any use of the adOCCT code and materials is on you. See the license text for a formal disclaimer.

Build from sources

adOCCT is currently being tested only on Linux distributions. To use it, adOCCT has to be built from sources to ensure compatibility with your platform (OS, compiler). The process of configuring and building adOCCT using CMake is very similar to the original OCCT workflow. Please consult the official Building OCCT page for instructions. Additional steps and requirements are described in the following.

The first step is to build and install ADOL-C release 2.7.2. When configuring it, one has to activate the flag --enable-atrig-erf. For example, ADOL-C installation process can be executed as follows:

./configure --prefix=ADOLC_PREFIX --enable-atrig-erf
make && make install

where ADOLC_PREFIX is the destination where header and library files are going to be installed.

Next, one can proceed with configuring and building adOCCT as follows:

1. Checkout ad/master branch (should be done by default).
2. Configure adOCCT using CMake by setting the following variable: USE_ADOLC=ON. After that, a PkgConfig module for CMake is loaded to search for the existing ADOL-C installation. If it fails to find it, which can be the case with a local ADOL-C installation that is not added to common search paths, one has to manually set a variable 3RDPARTY_ADOLC_DIR to the path where ADOL-C installation resides (i.e., ADOLC_PREFIX described previously). From that, the variables for the ADOL-C include and library directory are automatically derived.
3. To activate the reverse mode of AD, set the variable ADOLC_REVERSE_MODE=ON. This will build adOCCT using the trace-based headers of ADOL-C, otherwise the traceless header of ADOL-C is employed which allows only the forward mode of AD.
4. Optionally, if ADOL-C has been built with Boost, one can provide the used Boost installation directory using the variable 3RDPARTY_BOOST_DIR. This option makes the traceless feature of ADOL-C more performant as Boost is used to handle the memory management of adouble objects.
5. Optionally, one can build AD-tests by setting BUILD_AD_TESTS=ON.
6. Once the configuring is done, proceed with make && make install.

Note: -Wextra has been removed from CMAKE_CXX_FLAGS in the file adm/cmake/occt_defs_flags.cmake to discard warnings regarding ADOL-C.

Version

The current version of adOCCT can be found in the file adm/cmake/version.cmake.

Cite as

• Banović, M., Mykhaskiv, O., Auriemma, S., Walther, A., Legrand, H., and Müller, J. D. (2018). Algorithmic differentiation of the Open CASCADE Technology CAD kernel and its coupling with an adjoint CFD solver. Optimization Methods and Software, 33(4–6), 813–828. https://doi.org/10.1080/10556788.2018.1431235
• Hafemann, T., Banović, M. , Büchner, A. , Ehrmanntraut, S., Höing, C., Gottfried, S., and Stück, A. (2024). A CAD-enabled MDAO Framework Approach for Gradient-based Aerodynamic Shape Optimization. In: 9th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2024). https://doi.org/10.23967/eccomas.2024.199

Note

The software is provided as is. We sincerely welcome your feedback on issues, bugs and possible improvements. Please use the issue tracker of the project for the corresponding communication or make a fork. Our priority and timeline for working on the issues depend on the project and its follow-ups. This may lead to issue and tickets, which are not pursued. In case you need an urgent fix, please contact us directly for discussing possible forms of collaboration (direct contribution, projects, contracting, ...): Institute of Software Methods for Product Virtualization