delaunay_3d.h

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#ifndef GEOGRAM_DELAUNAY_DELAUNAY_3D
#define GEOGRAM_DELAUNAY_DELAUNAY_3D
 
#include <geogram/basic/common.h>
#include <geogram/delaunay/delaunay.h>
#include <geogram/delaunay/cavity.h>
#include <geogram/numerics/predicates.h>
#include <geogram/basic/geometry.h>
 
#include <stack>
 
namespace GEO {
 
    class GEOGRAM_API Delaunay3d : public Delaunay {
    public:
        Delaunay3d(coord_index_t dimension = 3);
 
        void set_vertices(
            index_t nb_vertices, const double* vertices
        ) override;
 
        index_t nearest_vertex(const double* p) const override;
 
 
    protected:
 
        static constexpr index_t NO_TETRAHEDRON = index_t(-1);
 
        bool create_first_tetrahedron(
            index_t& iv0, index_t& iv1, index_t& iv2, index_t& iv3
        );
 
        index_t locate(
            const double* p, index_t hint = NO_TETRAHEDRON,
            bool thread_safe = false,
            Sign* orient = nullptr
        ) const;
 
        index_t locate_inexact(
            const double* p, index_t hint, index_t max_iter
        ) const;
 
        index_t insert(index_t v, index_t hint = NO_TETRAHEDRON);
 
        void find_conflict_zone(
            index_t v,
            index_t t, const Sign* orient,
            index_t& t_bndry, index_t& f_bndry,
            index_t& first, index_t& last
        );
 
        void find_conflict_zone_iterative(
            const double* p, index_t t,
            index_t& t_bndry, index_t& f_bndry,
            index_t& first, index_t& last
        );
 
        index_t stellate_cavity(index_t v);
 
 
        index_t stellate_conflict_zone_iterative(
            index_t v,
            index_t t_bndry, index_t f_bndry,
            index_t prev_f=index_t(-1)
        );
 
        bool get_neighbor_along_conflict_zone_border(
            index_t t1,
            index_t t1fborder,
            index_t t1ft2,
            index_t& t2,
            index_t& t2fborder,
            index_t& t2ft1
        ) const {
 
            // Note: this function is a bit long for an inline function,
            // but I observed a (modest) performance gain doing so.
 
            //   Find two vertices that are both on facets new_f and f1
            //  (the edge around which we are turning)
            //  This uses duality as follows:
            //  Primal form (not used here):
            //    halfedge_facet_[v1][v2] returns a facet that is incident
            //    to both v1 and v2.
            //  Dual form (used here):
            //    halfedge_facet_[f1][f2] returns a vertex that both
            //    f1 and f2 are incident to.
            signed_index_t ev1 =
                tet_vertex(t1, index_t(halfedge_facet_[t1ft2][t1fborder]));
            signed_index_t ev2 =
                tet_vertex(t1, index_t(halfedge_facet_[t1fborder][t1ft2]));
 
            //   Turn around edge [ev1,ev2] inside the conflict zone
            // until we reach again the boundary of the conflict zone.
            // Traversing inside the conflict zone is faster (as compared
            // to outside) since it traverses a smaller number of tets.
            index_t cur_t = t1;
            index_t cur_f = t1ft2;
            index_t next_t = index_t(tet_adjacent(cur_t,cur_f));
            while(tet_is_in_list(next_t)) {
                geo_debug_assert(next_t != t1);
                cur_t = next_t;
                cur_f = get_facet_by_halfedge(cur_t,ev1,ev2);
                next_t = index_t(tet_adjacent(cur_t, cur_f));
            }
 
            //  At this point, cur_t is in conflict zone and
            // next_t is outside the conflict zone.
            index_t f12,f21;
            get_facets_by_halfedge(next_t, ev1, ev2, f12, f21);
            t2 = index_t(tet_adjacent(next_t,f21));
            signed_index_t v_neigh_opposite = tet_vertex(next_t,f12);
            t2ft1 = find_tet_vertex(t2, v_neigh_opposite);
            t2fborder = cur_f;
 
            //  Test whether the found neighboring tet was created
            //  (then return true) or is an old tet in conflict
            //  (then return false).
            return(t2 != cur_t);
        }
 
        // _________ Combinatorics - new and delete _________________________
 
        index_t max_t() const {
            return cell_to_v_store_.size() / 4;
        }
 
 
        static constexpr index_t NOT_IN_LIST  = index_t(~0);
 
        static constexpr index_t NOT_IN_LIST_BIT = index_t(1u << 31);
 
        static constexpr index_t END_OF_LIST = ~(NOT_IN_LIST_BIT);
 
 
        bool tet_is_in_list(index_t t) const {
            geo_debug_assert(t < max_t());
            return (cell_next_[t] & NOT_IN_LIST_BIT) == 0;
        }
 
        index_t tet_next(index_t t) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(tet_is_in_list(t));
            return cell_next_[t];
        }
 
        void add_tet_to_list(index_t t, index_t& first, index_t& last) {
            geo_debug_assert(t < max_t());
            geo_debug_assert(!tet_is_in_list(t));
            if(last == END_OF_LIST) {
                geo_debug_assert(first == END_OF_LIST);
                first = last = t;
                cell_next_[t] = END_OF_LIST;
            } else {
                cell_next_[t] = first;
                first = t;
            }
        }
 
        void remove_tet_from_list(index_t t) {
            geo_debug_assert(t < max_t());
            geo_debug_assert(tet_is_in_list(t));
            cell_next_[t] = NOT_IN_LIST;
        }
 
        static constexpr signed_index_t VERTEX_AT_INFINITY = -1;
 
        bool tet_is_finite(index_t t) const {
            return
                cell_to_v_store_[4 * t]     >= 0 &&
                cell_to_v_store_[4 * t + 1] >= 0 &&
                cell_to_v_store_[4 * t + 2] >= 0 &&
                cell_to_v_store_[4 * t + 3] >= 0;
        }
 
        bool tet_is_real(index_t t) const {
            return !tet_is_free(t) && tet_is_finite(t);
        }
 
        bool tet_is_virtual(index_t t) const {
            return
                !tet_is_free(t) && (
                    cell_to_v_store_[4 * t] == VERTEX_AT_INFINITY ||
                    cell_to_v_store_[4 * t + 1] == VERTEX_AT_INFINITY ||
                    cell_to_v_store_[4 * t + 2] == VERTEX_AT_INFINITY ||
                    cell_to_v_store_[4 * t + 3] == VERTEX_AT_INFINITY) ;
        }
 
        bool tet_is_free(index_t t) const {
            return tet_is_in_list(t);
        }
 
        index_t new_tetrahedron() {
            index_t result;
            if(first_free_ == END_OF_LIST) {
                cell_to_v_store_.resize(cell_to_v_store_.size() + 4, -1);
                cell_to_cell_store_.resize(cell_to_cell_store_.size() + 4, -1);
                // index_t(NOT_IN_LIST) is necessary, else with
                // NOT_IN_LIST alone the compiler tries to generate a
                // reference to NOT_IN_LIST resulting in a link error.
                cell_next_.push_back(index_t(NOT_IN_LIST));
                result = max_t() - 1;
            } else {
                result = first_free_;
                first_free_ = tet_next(first_free_);
                remove_tet_from_list(result);
            }
 
            cell_to_cell_store_[4 * result] = -1;
            cell_to_cell_store_[4 * result + 1] = -1;
            cell_to_cell_store_[4 * result + 2] = -1;
            cell_to_cell_store_[4 * result + 3] = -1;
 
            return result;
        }
 
        index_t new_tetrahedron(
            signed_index_t v1, signed_index_t v2,
            signed_index_t v3, signed_index_t v4
        ) {
            index_t result = new_tetrahedron();
            cell_to_v_store_[4 * result] = v1;
            cell_to_v_store_[4 * result + 1] = v2;
            cell_to_v_store_[4 * result + 2] = v3;
            cell_to_v_store_[4 * result + 3] = v4;
            return result;
        }
 
        void set_tet_mark_stamp(index_t stamp) {
            cur_stamp_ = (stamp | NOT_IN_LIST_BIT);
        }
 
        bool tet_is_marked(index_t t) const {
            return cell_next_[t] == cur_stamp_;
        }
 
        void mark_tet(index_t t) {
            cell_next_[t] = cur_stamp_;
        }
 
        // _________ Combinatorics ___________________________________
 
        static index_t tet_facet_vertex(index_t f, index_t v) {
            geo_debug_assert(f < 4);
            geo_debug_assert(v < 3);
            return index_t(tet_facet_vertex_[f][v]);
        }
 
        signed_index_t tet_vertex(index_t t, index_t lv) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(lv < 4);
            return cell_to_v_store_[4 * t + lv];
        }
 
        index_t find_tet_vertex(index_t t, signed_index_t v) const {
            geo_debug_assert(t < max_t());
            //   Find local index of v in tetrahedron t vertices.
            const signed_index_t* T = &(cell_to_v_store_[4 * t]);
            return find_4(T,v);
        }
 
 
        index_t finite_tet_vertex(index_t t, index_t lv) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(lv < 4);
            geo_debug_assert(cell_to_v_store_[4 * t + lv] != -1);
            return index_t(cell_to_v_store_[4 * t + lv]);
        }
 
        void set_tet_vertex(index_t t, index_t lv, signed_index_t v) {
            geo_debug_assert(t < max_t());
            geo_debug_assert(lv < 4);
            cell_to_v_store_[4 * t + lv] = v;
        }
 
        signed_index_t tet_adjacent(index_t t, index_t lf) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(lf < 4);
            signed_index_t result = cell_to_cell_store_[4 * t + lf];
            return result;
        }
 
        void set_tet_adjacent(index_t t1, index_t lf1, index_t t2) {
            geo_debug_assert(t1 < max_t());
            geo_debug_assert(t2 < max_t());
            geo_debug_assert(lf1 < 4);
            cell_to_cell_store_[4 * t1 + lf1] = signed_index_t(t2);
        }
 
        index_t find_tet_adjacent(
            index_t t1, index_t t2_in
        ) const {
            geo_debug_assert(t1 < max_t());
            geo_debug_assert(t2_in < max_t());
            geo_debug_assert(t1 != t2_in);
 
            signed_index_t t2 = signed_index_t(t2_in);
 
            // Find local index of t2 in tetrahedron t1 adajcent tets.
            const signed_index_t* T = &(cell_to_cell_store_[4 * t1]);
            index_t result = find_4(T,t2);
 
            // Sanity check: make sure that t1 is adjacent to t2
            // only once!
            geo_debug_assert(tet_adjacent(t1,(result+1)%4) != t2);
            geo_debug_assert(tet_adjacent(t1,(result+2)%4) != t2);
            geo_debug_assert(tet_adjacent(t1,(result+3)%4) != t2);
            return result;
        }
 
 
 
        void set_tet(
            index_t t,
            signed_index_t v0, signed_index_t v1,
            signed_index_t v2, signed_index_t v3,
            index_t a0, index_t a1, index_t a2, index_t a3
        ) {
            geo_debug_assert(t < max_t());
            cell_to_v_store_[4 * t] = v0;
            cell_to_v_store_[4 * t + 1] = v1;
            cell_to_v_store_[4 * t + 2] = v2;
            cell_to_v_store_[4 * t + 3] = v3;
            cell_to_cell_store_[4 * t] = signed_index_t(a0);
            cell_to_cell_store_[4 * t + 1] = signed_index_t(a1);
            cell_to_cell_store_[4 * t + 2] = signed_index_t(a2);
            cell_to_cell_store_[4 * t + 3] = signed_index_t(a3);
        }
 
        // _________ Combinatorics - traversals ______________________________
 
        index_t get_facet_by_halfedge(
            index_t t, signed_index_t v1, signed_index_t v2
        ) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(v1 != v2);
            //   Find local index of v1 and v2 in tetrahedron t
            const signed_index_t* T = &(cell_to_v_store_[4 * t]);
            index_t lv1 = find_4(T,v1);
            index_t lv2 = find_4(T,v2);
            geo_debug_assert(lv1 != lv2);
            return index_t(halfedge_facet_[lv1][lv2]);
        }
 
 
        void get_facets_by_halfedge(
            index_t t, signed_index_t v1, signed_index_t v2,
            index_t& f12, index_t& f21
        ) const {
            geo_debug_assert(t < max_t());
            geo_debug_assert(v1 != v2);
 
            //   Find local index of v1 and v2 in tetrahedron t
            // The following expression is 10% faster than using
            // if() statements (multiply by boolean result of test).
            // Thank to Laurent Alonso for this idea.
            const signed_index_t* T = &(cell_to_v_store_[4 * t]);
 
            signed_index_t lv1 =
                (T[1] == v1) | ((T[2] == v1) * 2) | ((T[3] == v1) * 3);
 
            signed_index_t lv2 =
                (T[1] == v2) | ((T[2] == v2) * 2) | ((T[3] == v2) * 3);
 
            geo_debug_assert(lv1 != 0 || T[0] == v1);
            geo_debug_assert(lv2 != 0 || T[0] == v2);
            geo_debug_assert(lv1 >= 0);
            geo_debug_assert(lv2 >= 0);
            geo_debug_assert(lv1 != lv2);
 
            f12 = index_t(halfedge_facet_[lv1][lv2]);
            f21 = index_t(halfedge_facet_[lv2][lv1]);
        }
 
 
        index_t next_around_halfedge(
            index_t& t, signed_index_t v1, signed_index_t v2
        ) const {
            return (index_t)tet_adjacent(
                t, get_facet_by_halfedge(t, v1, v2)
            );
        }
 
        // _________ Predicates _____________________________________________
 
        bool tet_is_conflict(index_t t, const double* p) const {
 
            // Lookup tetrahedron vertices
            const double* pv[4];
            for(index_t i=0; i<4; ++i) {
                signed_index_t v = tet_vertex(t,i);
                pv[i] = (v == -1) ? nullptr : vertex_ptr(index_t(v));
            }
 
            // Check for virtual tetrahedra (then in_sphere()
            // is replaced with orient3d())
            for(index_t lf = 0; lf < 4; ++lf) {
 
                if(pv[lf] == nullptr) {
 
                    // Facet of a virtual tetrahedron opposite to
                    // infinite vertex corresponds to
                    // the triangle on the convex hull of the points.
                    // Orientation is obtained by replacing vertex lf
                    // with p.
                    pv[lf] = p;
                    Sign sign = PCK::orient_3d(pv[0],pv[1],pv[2],pv[3]);
 
                    if(sign > 0) {
                        return true;
                    }
 
                    if(sign < 0) {
                        return false;
                    }
 
                    // If sign is zero, we check the real tetrahedron
                    // adjacent to the facet on the convex hull.
                    geo_debug_assert(tet_adjacent(t, lf) >= 0);
                    index_t t2 = index_t(tet_adjacent(t, lf));
                    geo_debug_assert(!tet_is_virtual(t2));
 
                    //  If t2 is already chained in the conflict list,
                    // then it is conflict
                    if(tet_is_in_list(t2)) {
                        return true;
                    }
 
                    //  If t2 is marked, then it is not in conflict.
                    if(tet_is_marked(t2)) {
                        return false;
                    }
 
                    return tet_is_conflict(t2, p);
                }
            }
 
            //   If the tetrahedron is a finite one, it is in conflict
            // if its circumscribed sphere contains the point (this is
            // the standard case).
 
            if(weighted_) {
                double h0 = heights_[finite_tet_vertex(t, 0)];
                double h1 = heights_[finite_tet_vertex(t, 1)];
                double h2 = heights_[finite_tet_vertex(t, 2)];
                double h3 = heights_[finite_tet_vertex(t, 3)];
                index_t pindex = index_t(
                    (p - vertex_ptr(0)) / int(vertex_stride_)
                );
                double h = heights_[pindex];
                return (PCK::orient_3dlifted_SOS(
                            pv[0],pv[1],pv[2],pv[3],p,h0,h1,h2,h3,h
                        ) > 0) ;
            }
 
            return (PCK::in_sphere_3d_SOS(pv[0], pv[1], pv[2], pv[3], p) > 0);
        }
 
    protected:
 
        static index_t find_4(const signed_index_t* T, signed_index_t v) {
            // The following expression is 10% faster than using
            // if() statements. This uses the C++ norm, that
            // ensures that the 'true' boolean value converted to
            // an int is always 1. With most compilers, this avoids
            // generating branching instructions.
            // Thank to Laurent Alonso for this idea.
            // Note: Laurent also has this version:
            //    (T[0] != v)+(T[2]==v)+2*(T[3]==v)
            // that avoids a *3 multiply, but it is not faster in
            // practice.
            index_t result = index_t(
                (T[1] == v) | ((T[2] == v) * 2) | ((T[3] == v) * 3)
            );
            // Sanity check, important if it was T[0], not explicitly
            // tested (detects input that does not meet the precondition).
            geo_debug_assert(T[result] == v);
            return result;
        }
 
        ~Delaunay3d() override;
 
        void show_tet(index_t t) const;
 
        void show_tet_adjacent(index_t t, index_t lf) const;
 
        void show_list(
            index_t first, const std::string& list_name
        ) const;
 
        void check_combinatorics(bool verbose = false) const;
 
        void check_geometry(bool verbose = false) const;
 
    private:
        vector<signed_index_t> cell_to_v_store_;
        vector<signed_index_t> cell_to_cell_store_;
        vector<index_t> cell_next_;
        vector<index_t> reorder_;
        index_t cur_stamp_; // used for marking
        index_t first_free_;
        bool weighted_;
        vector<double> heights_; // only used in weighted mode
 
        bool debug_mode_;
 
        bool verbose_debug_mode_;
 
        bool benchmark_mode_;
 
        static char tet_facet_vertex_[4][3];
 
        static char halfedge_facet_[4][4];
 
        std::stack<index_t> S_;
 
        class StellateConflictStack {
        public:
 
            void push(index_t t1, index_t t1fbord, index_t t1fprev) {
                store_.resize(store_.size()+1);
                top().t1 = t1;
                top().t1fbord = Numeric::uint8(t1fbord);
                top().t1fprev = Numeric::uint8(t1fprev);
            }
 
            void save_locals(index_t new_t, index_t t1ft2, index_t t2ft1) {
                geo_debug_assert(!empty());
                top().new_t = new_t;
                top().t1ft2 = Numeric::uint8(t1ft2);
                top().t2ft1 = Numeric::uint8(t2ft1);
            }
 
            void get_parameters(
                index_t& t1, index_t& t1fbord, index_t& t1fprev
            ) const {
                geo_debug_assert(!empty());
                t1      = top().t1;
                t1fbord = index_t(top().t1fbord);
                t1fprev = index_t(top().t1fprev);
            }
 
 
            void get_locals(
                index_t& new_t, index_t& t1ft2, index_t& t2ft1
            ) const {
                geo_debug_assert(!empty());
                new_t = top().new_t;
                t1ft2 = index_t(top().t1ft2);
                t2ft1 = index_t(top().t2ft1);
            }
 
            void pop() {
                geo_debug_assert(!empty());
                store_.pop_back();
            }
 
            bool empty() const {
                return store_.empty();
            }
 
        private:
 
            struct Frame {
                // Parameters
                index_t t1;
                index_t new_t;
                Numeric::uint8 t1fbord ;
 
                // Local variables
                Numeric::uint8 t1fprev ;
                Numeric::uint8 t1ft2   ;
                Numeric::uint8 t2ft1   ;
            };
 
            Frame& top() {
                geo_debug_assert(!empty());
                return *store_.rbegin();
            }
 
            const Frame& top() const {
                geo_debug_assert(!empty());
                return *store_.rbegin();
            }
 
            std::vector<Frame> store_;
        };
 
        StellateConflictStack S2_;
 
        Cavity cavity_;
    };
 
    /************************************************************************/
 
    class GEOGRAM_API RegularWeightedDelaunay3d : public Delaunay3d {
    public:
        RegularWeightedDelaunay3d(coord_index_t dimension = 4);
 
    protected:
        ~RegularWeightedDelaunay3d() override;
    };
}
 
#endif