isosurface.h

//
// Created by RainSure on 2024/2/29.
//
 
#ifndef RSMESH_ISOSURFACE_H
#define RSMESH_ISOSURFACE_H
 
#include "geometry/bbox3d.h"
#include "geometry/point3d.h"
#include "isosurface/mesh_defects_finder.h"
#include "isosurface/rmt_lattice.h"
#include "isosurface/rmt_surface.h"
#include "isosurface/surface.h"
#include <unordered_set>
 
 
namespace rsmesh::isosurface {
    class isosurface {
    public:
        isosurface(const geometry::bbox3d& bbox, double resolution) : rmt_lattice_(bbox, resolution) {}
 
        surface generate(field_function& field_fn, double isovalue = 0.0) {
            field_fn.set_evaluation_bbox(rmt_lattice_.extended_bbox());
 
            rmt_lattice_.add_all_nodes(field_fn, isovalue);
 
            return generate_common();
        }
 
        surface generate_from_seed_points(const geometry::points3d& seed_points, field_function& field_fn,
                                          double isovalue = 0.0) {
            field_fn.set_evaluation_bbox(rmt_lattice_.extended_bbox());
 
            for (auto p : seed_points.rowwise()) {
                rmt_lattice_.add_cell_contains_point(p);
            }
            rmt_lattice_.add_nodes_by_tracking(field_fn, isovalue);
 
            return generate_common();
        }
 
    private:
        surface generate_common() {
            rmt_lattice_.cluster_vertices();
 
            rmt_surface rmt_surf(rmt_lattice_);
            rmt_surf.generate_surface();
 
            // Unclustering non-manifold vertices may require a few iterations.
            while (true) {
                auto vertices = rmt_lattice_.get_vertices();
                auto faces = rmt_surf.get_faces();
                mesh_defects_finder defects(vertices, faces);
 
                auto vis = defects.singular_vertices();
                auto fis = defects.intersecting_faces();
 
                std::unordered_set<vertex_index> vertices_to_uncluster;
                for (auto vi : vis) {
                    vertices_to_uncluster.insert(vi);
                }
                for (auto fi : fis) {
                    auto f = faces.row(fi);
                    vertices_to_uncluster.insert(f(0));
                    vertices_to_uncluster.insert(f(1));
                    vertices_to_uncluster.insert(f(2));
                }
 
                rmt_lattice_.uncluster_vertices(vertices_to_uncluster);
 
                // fis.empty() is not checked as it is not possible to eliminate all self intersections.
                if (vis.empty()) {
                    break;
                }
            }
 
            surface surf(rmt_lattice_.get_vertices(), rmt_surf.get_faces());
 
            rmt_lattice_.clear();
 
            return surf;
        }
 
        rmt_lattice rmt_lattice_;
    };
}
 
#endif //RSMESH_ISOSURFACE_H