Particle generation breaks restart feature

[FabienPean-Virtonomy]

SPHinXsys/SPHINXsys/src/shared/bodies/base_body.h

Lines 137 to 144 in e5d224d

	template <class ParticleGeneratorType, typename... ConstructorArgs>
	void generateParticles(ConstructorArgs &&...args)
	{
	ParticleGeneratorType particle_generator(*this, std::forward<ConstructorArgs>(args)...);
	particle_generator.initializeGeometricVariables();
	base_particles_->initializeOtherVariables();
	base_material_->assignBaseParticles(base_particles_);
	};

Restart is inherently broken with new particle generation approach. For any particle generator, initializeOtherVariables happens after the function implemented by the user, the initialization of extra variable based on a function such as

SPHinXsys/SPHINXsys/src/shared/particles/solid_particles.cpp

Lines 30 to 32 in e5d224d

	registerVariable(n0_, "InitialNormalDirection",
	[&](size_t i) -> Vecd
	{ return n_[i]; });

is (1) crashing if the variable was registered by the user inadvertently (avoidable and ok, requires removing some lines), and (2) overriding any user/file loaded values (more problematic from design POV). See the sources of problems in base_particles.hpp

SPHinXsys/SPHINXsys/src/shared/particles/base_particles.hpp

Lines 45 to 56 in e5d224d

	if (all_variable_maps_[type_index].find(variable_name) == all_variable_maps_[type_index].end())
	{
	variable_addrs.resize(real_particles_bound_, initial_value);
	std::get<type_index>(all_particle_data_).push_back(&variable_addrs);
	all_variable_maps_[type_index].insert(make_pair(variable_name, std::get<type_index>(all_particle_data_).size() - 1));
	}
	else
	{
	std::cout << "\n Error: the variable '" << variable_name << "' has already been registered!" << std::endl;
	std::cout << __FILE__ << ':' << __LINE__ << std::endl;
	exit(1);
	}

and

SPHinXsys/SPHINXsys/src/shared/particles/base_particles.hpp

Lines 59 to 71 in e5d224d

	template <typename VariableType, class InitializationFunction>
	void BaseParticles::
	registerVariable(StdLargeVec<VariableType> &variable_addrs,
	const std::string &variable_name, const InitializationFunction &initialization)
	{
	constexpr int type_index = DataTypeIndex<VariableType>::value;
	registerVariable(variable_addrs, variable_name);
	for (size_t i = 0; i != real_particles_bound_; ++i)
	{
	variable_addrs[i] = initialization(i);
	}
	}

[Xiangyu-Hu]

Yes. This issue is very relevant to that a variable is only allowed once. The other Variable are only those in particle classes. Any new variable will be defined in method will be initialized in the specific method class. My original design is separate geometric model variable, physical model variables and dynamics relevant variables. The first two are defined in particles, the third in method classes. However, the clear separation between the three is not very obvious.