I was trying to draw the HalfEdge Data Structure solid with openGL, and I have to subdivision face which may have holes and turn the face to triangles. I use the poly2tri lib. Relate Code is blow.

void Renderer::Poly2Triangles(Face* face)
{
    Plane2D plane(face);
    std::vector<p2t::Point*> all_points;
    std::vector<p2t::Point*> out_points;
    std::vector<p2t::Point*> in_points;

    //outter loop
    Loop* outerLoop = face->fLoops;
    while (outerLoop->IsInnerLoop) outerLoop = outerLoop->lNext;
    glm::vec3 firstEdge = (outerLoop->lHEdge->destination->Pos).position - (outerLoop->lHEdge->origin->Pos).position;
    glm::vec3 secondEdge = (outerLoop->lHEdge->Next->destination->Pos).position - (outerLoop->lHEdge->Next->origin->Pos).position;
    glm::vec3 norm = glm::normalize(glm::cross(firstEdge, secondEdge));
    HalfEdge* he = outerLoop->lHEdge;
    do {
        glm::vec2 p = plane.Space3DToPlane2D((he->origin->Pos).position);
        p2t::Point* point = new p2t::Point(p.x, p.y);
        all_points.push_back(point);
        out_points.push_back(point);
        he = he->Next;
    } while (he != outerLoop->lHEdge);
    p2t::CDT cdt(std::move(out_points)); //-----------first link error here--------------- 


    //inner loop
    Loop* innerLoop = face->fLoops;
    do {
        if (!(innerLoop->IsInnerLoop)) {
            innerLoop = innerLoop->lNext;
            continue;
        }

        HalfEdge* he = innerLoop->lHEdge;
        do {
            glm::vec2 p = plane.Space3DToPlane2D((he->origin->Pos).position);
            p2t::Point* point = new p2t::Point(p.x, p.y);
            in_points.push_back(point);
            all_points.push_back(point);
            he = he->Next;
        } while (he != innerLoop->lHEdge);

        cdt.AddHole(std::move(in_points));//----------------link error-------------
        innerLoop = innerLoop->lNext;
    } while (innerLoop != face->fLoops);

    cdt.Triangulate();//-----------------------link error------------------------ 


    auto tris = cdt.GetTriangles();//------------------------link error---------------------- 
    for (auto tri : tris) {
        Triangle triangle;
        for (int i = 0; i < 3; i++) {
            auto _p = tri->GetPoint(i);
            triangle.vertex[i] = plane.Plane2DToSpace3D(glm::vec2(_p->x, _p->y));
            triangle.normal[i] = norm;
        }
        triangles.push_back(triangle);
    }
    for (auto p : all_points)
        delete p;
}

When I try to run it, it shows five link error:

• Renderer.obj : error LNK2019: 无法解析的外部符号 “public: __thiscall p2t::CDT::CDT(class std::vector<struct p2t::Point *,class std::allocator<struct p2t::Point *> >)” (??0CDT@p2t@@QAE@V?$vector@PAUPoint@p2t@@V?$allocator@PAUPoint@p2t@@@std@@@std@@@Z)，函数 “private: void __thiscall Renderer::Poly2Triangles(class Face *)” (?Poly2Triangles@Renderer@@AAEXPAVFace@@@Z) 中引用了该符号

• 1>Renderer.obj : error LNK2019: 无法解析的外部符号 “public: __thiscall p2t::CDT::~CDT(void)” (??1CDT@p2t@@QAE@XZ)，函数 “private: void __thiscall Renderer::Poly2Triangles(class Face *)” (?Poly2Triangles@Renderer@@AAEXPAVFace@@@Z) 中引用了该符号

• 1>Renderer.obj : error LNK2019: 无法解析的外部符号 “public: void __thiscall p2t::CDT::AddHole(class std::vector<struct p2t::Point *,class std::allocator<struct p2t::Point *> >)” (?AddHole@CDT@p2t@@QAEXV?$vector@PAUPoint@p2t@@V?$allocator@PAUPoint@p2t@@@std@@@std@@@Z)，函数 “private: void __thiscall Renderer::Poly2Triangles(class Face *)” (?Poly2Triangles@Renderer@@AAEXPAVFace@@@Z) 中引用了该符号

• 1>Renderer.obj : error LNK2019: 无法解析的外部符号 “public: void __thiscall p2t::CDT::Triangulate(void)” (?Triangulate@CDT@p2t@@QAEXXZ)，函数 “private: void __thiscall Renderer::Poly2Triangles(class Face *)” (?Poly2Triangles@Renderer@@AAEXPAVFace@@@Z) 中引用了该符号

• 1>Renderer.obj : error LNK2019: 无法解析的外部符号 “public: class std::vector<class p2t::Triangle *,class std::allocator<class p2t::Triangle *> > __thiscall p2t::CDT::GetTriangles(void)” (?GetTriangles@CDT@p2t@@QAE?AV?$vector@PAVTriangle@p2t@@V?$allocator@PAVTriangle@p2t@@@std@@@std@@XZ)，函数 “private: void __thiscall Renderer::Poly2Triangles(class Face *)” (?Poly2Triangles@Renderer@@AAEXPAVFace@@@Z) 中引用了该符号

just all the p2t::CDT class member was unresolved external symbol: CDT、~CDT、CDT::AddHole、 CDT::Triangulate、CDT::GetTriangles

I use VS2022 build this project, I add the poly2tri header file to the include file path in project properties. the file structure is blow and I just #include "poly2tri.h". it actually pass the compile.

I have no idea what’s going on, I want to find errors and correct them. Or I’m happy to know other way to subdivision polygon to triangles.