RhsAssembler.hpp

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#pragma once
 
#include <polyfem/assembler/Assembler.hpp>
#include <polyfem/mesh/Obstacle.hpp>
 
#include <polyfem/assembler/Problem.hpp>
#include <polyfem/assembler/MatParams.hpp>
#include <polyfem/mesh/LocalBoundary.hpp>
 
namespace polyfem
{
    namespace assembler
    {
        // computes the rhs of a problem by \int \phi rho rhs
        class RhsAssembler
        {
        public:
            // initialization with assembler factory mesh
            // size of the problem, bases
            // and solver used internally
            RhsAssembler(
                const Assembler &assembler,
                const mesh::Mesh &mesh,
                const mesh::Obstacle &obstacle,
                const std::vector<int> &dirichlet_nodes,
                const std::vector<int> &neumann_nodes,
                const std::vector<RowVectorNd> &dirichlet_nodes_position,
                const std::vector<RowVectorNd> &neumann_nodes_position,
                const int n_basis,
                const int size,
                const std::vector<basis::ElementBases> &bases,
                const std::vector<basis::ElementBases> &gbases,
                const AssemblyValsCache &ass_vals_cache,
                const Problem &problem,
                const std::string bc_method,
                const json &solver_params);
 
            // computes the rhs of a problem by \int \phi rho rhs
            void assemble(const Density &density, Eigen::MatrixXd &rhs, const double t = 1) const;
 
            // computes the initial soltion for time dependent, calls time_bc
            void initial_solution(Eigen::MatrixXd &sol) const;
            // computes the initial velocity for time dependent, calls time_bc
            void initial_velocity(Eigen::MatrixXd &sol) const;
            // computes the initial acceleration for time dependent, calls time_bc
            void initial_acceleration(Eigen::MatrixXd &sol) const;
 
            // sets boundary conditions to rhs, the boundary conditions are projected (Dirichlet) integrated (Neumann) at resolution
            // local boundary stores the mapping from elemment to nodes for Dirichlet nodes
            // local local_neumann_boundary stores the mapping from elemment to nodes for Neumann nodes
            // calls set_bc
            void set_bc(
                const std::vector<mesh::LocalBoundary> &local_boundary,
                const std::vector<int> &bounday_nodes,
                const int resolution,
                const std::vector<mesh::LocalBoundary> &local_neumann_boundary,
                Eigen::MatrixXd &rhs,
                const Eigen::MatrixXd &displacement = Eigen::MatrixXd(),
                const double t = 1) const;
 
            // compute body energy
            double compute_energy(
                const Eigen::MatrixXd &displacement,
                const Eigen::MatrixXd &displacement_prev,
                const std::vector<mesh::LocalBoundary> &local_neumann_boundary,
                const Density &density,
                const int resolution,
                const double t) const;
            // compute body energy gradient, hessian is zero, rhs is a linear function
            void compute_energy_grad(
                const std::vector<mesh::LocalBoundary> &local_boundary,
                const std::vector<int> &bounday_nodes,
                const Density &density,
                const int resolution,
                const std::vector<mesh::LocalBoundary> &local_neumann_boundary,
                const Eigen::MatrixXd &final_rhs,
                const double t,
                Eigen::MatrixXd &rhs) const;
 
            // compute body hessian wrt to previous solution
            void compute_energy_hess(const std::vector<int> &bounday_nodes, const int resolution, const std::vector<mesh::LocalBoundary> &local_neumann_boundary, const Eigen::MatrixXd &displacement, const double t, const bool project_to_psd, StiffnessMatrix &hess) const;
 
            inline const Problem &problem() const { return problem_; }
            inline const mesh::Mesh &mesh() const { return mesh_; }
            inline const std::vector<basis::ElementBases> &bases() const { return bases_; }
            inline const std::vector<basis::ElementBases> &gbases() const { return gbases_; }
            inline const AssemblyValsCache &ass_vals_cache() const { return ass_vals_cache_; }
            inline const Assembler &assembler() const { return assembler_; }
 
        private:
            // leastsquares fit bc
            void lsq_bc(const std::function<void(const Eigen::MatrixXi &, const Eigen::MatrixXd &, const Eigen::MatrixXd &, Eigen::MatrixXd &)> &df,
                        const std::vector<mesh::LocalBoundary> &local_boundary, const std::vector<int> &bounday_nodes, const int resolution, Eigen::MatrixXd &rhs) const;
 
            // sample bc at nodes
            void sample_bc(const std::function<void(const Eigen::MatrixXi &, const Eigen::MatrixXd &, const Eigen::MatrixXd &, Eigen::MatrixXd &)> &df,
                           const std::vector<mesh::LocalBoundary> &local_boundary, const std::vector<int> &bounday_nodes, Eigen::MatrixXd &rhs) const;
 
            // set boundary condition
            // the 2 lambdas are callback to dirichlet df and neumann nf
            // diriclet boundary condition are projected on the FEM bases, it inverts a linear system
            void set_bc(
                const std::function<void(const Eigen::MatrixXi &, const Eigen::MatrixXd &, const Eigen::MatrixXd &, Eigen::MatrixXd &)> &df,
                const std::function<void(const Eigen::MatrixXi &, const Eigen::MatrixXd &, const Eigen::MatrixXd &, const Eigen::MatrixXd &, Eigen::MatrixXd &)> &nf,
                const std::vector<mesh::LocalBoundary> &local_boundary, const std::vector<int> &bounday_nodes, const int resolution, const std::vector<mesh::LocalBoundary> &local_neumann_boundary,
                const Eigen::MatrixXd &displacement, const double t, Eigen::MatrixXd &rhs) const;
 
            // sets the time (initial) boundary condition
            // the lambda depeneds if soltuion, velocity, or acceleration
            // they are projected on the FEM bases, it inverts a linear system
            void time_bc(const std::function<void(const mesh::Mesh &, const Eigen::MatrixXi &, const Eigen::MatrixXd &, Eigen::MatrixXd &)> &fun, Eigen::MatrixXd &sol) const;
 
            const Assembler &assembler_;
            const mesh::Mesh &mesh_;
            const mesh::Obstacle &obstacle_;
            const int n_basis_;
            const int size_;                                 
            const std::vector<basis::ElementBases> &bases_;  
            const std::vector<basis::ElementBases> &gbases_; 
            const AssemblyValsCache &ass_vals_cache_;
            const Problem &problem_;
            const std::string bc_method_;
            const json solver_params_;
            const std::vector<int> &dirichlet_nodes_;
            const std::vector<RowVectorNd> &dirichlet_nodes_position_;
            const std::vector<int> &neumann_nodes_;
            const std::vector<RowVectorNd> &neumann_nodes_position_;
        };
    } // namespace assembler
} // namespace polyfem