SPHinXsys provides C++ APIs for engineering simulation and optimization. It aims at complex systems driven by fluid, structure, multi-body dynamics and beyond. The multi-physics library is based on a unique and unified computational framework by which strong coupling has been achieved for all involved physics.
https://github.com/Xiangyu-Hu/SPHinXsys/blob/fcff55f326ec1d563498c852e5c209511ca35316/src/shared/sphinxsys_system/sph_system.h#L94-L96 I did not find anything in cmake file for this definition anymore.