triangle_intersection.h

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#ifndef GEOGRAM_MESH_TRIANGLE_INTERSECTION
#define GEOGRAM_MESH_TRIANGLE_INTERSECTION
 
#include <geogram/basic/common.h>
#include <geogram/basic/geometry.h>
#include <geogram/basic/memory.h>
#include <utility>
 
namespace GEO {
 
    enum TriangleRegion {
        T1_RGN_P0 = 0,
        T1_RGN_P1 = 1,
        T1_RGN_P2 = 2,
 
        T2_RGN_P0 = 3,
        T2_RGN_P1 = 4,
        T2_RGN_P2 = 5,
 
        T1_RGN_E0 = 6,
        T1_RGN_E1 = 7,
        T1_RGN_E2 = 8,
 
        T2_RGN_E0 = 9,
        T2_RGN_E1 = 10,
        T2_RGN_E2 = 11,
 
        T1_RGN_T  = 12,
        T2_RGN_T  = 13,
 
        T_RGN_NB  = 14
    };
 
 
    inline bool is_in_T1(TriangleRegion R) {
        return (R == T1_RGN_P0) ||
            (R == T1_RGN_P1) ||
            (R == T1_RGN_P2) ||
            (R == T1_RGN_E0) ||
            (R == T1_RGN_E1) ||
            (R == T1_RGN_E2) ||
            (R == T1_RGN_T ) ;
    }
 
    TriangleRegion GEOGRAM_API swap_T1_T2(TriangleRegion R);
 
    typedef std::pair<TriangleRegion, TriangleRegion> TriangleIsect;
 
 
    class TriangleIsects {
    public:
        TriangleIsects() : size_(0) {
        }
 
        typedef TriangleIsect* iterator;
        typedef const TriangleIsect* const_iterator;
 
        iterator begin() {
            return data_;
        }
 
        iterator end() {
            return begin()+size_;
        }
 
        const_iterator begin() const {
            return data_;
        }
 
        const_iterator end() const {
            return begin()+size_;
        }
 
        void push_back(const TriangleIsect& I) {
            geo_assert(size_ < capacity_);
            data_[size_] = I;
            ++size_;
        }
 
        void clear() {
            size_ = 0;
        }
 
        index_t size() const {
            return size_;
        }
 
        void resize(index_t new_size) {
            geo_debug_assert(new_size <= capacity_);
            size_ = new_size;
        }
 
        TriangleIsect& operator[](index_t i) {
            geo_debug_assert(i<size());
            return data_[i];
        }
 
        const TriangleIsect& operator[](index_t i) const {
            geo_debug_assert(i<size());
            return data_[i];
        }
 
    private:
        static constexpr int capacity_ = 20;
        index_t size_;
        TriangleIsect data_[capacity_];
    };
 
 
    bool GEOGRAM_API triangles_intersections(
        const vec3& p0, const vec3& p1, const vec3& p2,
        const vec3& q0, const vec3& q1, const vec3& q2,
        TriangleIsects& result
    );
 
 
    [[deprecated("use TriangleIsects instead of vector<TriangleIsect>")]]
    inline bool triangles_intersections(
        const vec3& p0, const vec3& p1, const vec3& p2,
        const vec3& q0, const vec3& q1, const vec3& q2,
        vector<TriangleIsect>& result
    ) {
        TriangleIsects result_;
        bool r = triangles_intersections(p0,p1,p2,q0,q1,q2,result_);
        result.clear();
        for(TriangleIsect I : result_) {
            result.push_back(I);
        }
        return r;
    }
 
 
    bool GEOGRAM_API triangles_intersections(
        const vec3& p0, const vec3& p1, const vec3& p2,
        const vec3& q0, const vec3& q1, const vec3& q2,
        index_t p0_index,
        index_t p1_index,
        index_t p2_index,
        index_t q0_index,
        index_t q1_index,
        index_t q2_index,
        TriangleIsects& result
    );
 
 
    bool triangles_intersections(
        const vec3& p0, const vec3& p1, const vec3& p2,
        const vec3& q0, const vec3& q1, const vec3& q2
    );
 
    std::string GEOGRAM_API region_to_string(TriangleRegion rgn);
 
    coord_index_t GEOGRAM_API region_dim(TriangleRegion r);
 
    void GEOGRAM_API get_triangle_vertices(
        TriangleRegion T,
        TriangleRegion& p0, TriangleRegion& p1, TriangleRegion& p2
    );
 
    void GEOGRAM_API get_triangle_edges(
        TriangleRegion T,
        TriangleRegion& e0, TriangleRegion& e1, TriangleRegion& e2
    );
 
    void GEOGRAM_API get_edge_vertices(
        TriangleRegion E, TriangleRegion& q0, TriangleRegion& q1
    );
 
 
    TriangleRegion GEOGRAM_API regions_convex_hull(
        TriangleRegion R1, TriangleRegion R2
    );
 
    inline std::ostream& operator<<(
        std::ostream& out, const TriangleIsect& I
    ) {
        return (
            out << "("
            << region_to_string(I.first) << ","
            << region_to_string(I.second)
            << ")"
        );
    }
 
    inline std::ostream& operator<<(
        std::ostream& out, TriangleIsects& II
    ) {
        for(const TriangleIsect& I : II) {
            out << I << " ";
        }
        return out;
    }
 
    [[deprecated("use TriangleIsects instead of vector<TriangleIsect>")]]
    inline std::ostream& operator<<(
        std::ostream& out, const vector<TriangleIsect>& II
    ) {
        for(const TriangleIsect& I : II) {
            out << I << " ";
        }
        return out;
    }
 
 
}
 
#endif