c++ - CGAL:从表面网格获取人脸数据

Question

我试图用从 CGAL::Surface_mesh 检索到的数据填充我自己的结构。

您可以通过..将面添加到表面网格

CGAL::SM_Face_index face = SM_Surface_Mesh.add_face(SM_Vertex_Index, SM_Vertex_Index, SM_Vertex_Index);

.. 但是如何根据 SM_Face_Index 检索那张脸呢？我已尝试筛选文档，但无济于事。

InteropMesh * outputMesh = new InteropMesh();
uint32_t num = mesh1.number_of_vertices();

outputMesh->vertexCount = num;

outputMesh->vertices = new InteropVector3[num];

for (Mesh::Vertex_index vd : mesh1.vertices()) 
{
    uint32_t index = vd; //via size_t

    Point data = mesh1.point(vd);
    outputMesh->vertices[index].x = (float)data.x();
    outputMesh->vertices[index].y = (float)data.y();
    outputMesh->vertices[index].z = (float)data.z();
}

outputMesh->indices = new uint32_t[mesh1.number_of_faces() * 3];

for (CGAL::SM_Face_index fd : mesh1.faces())
{
    //? How do I get the three vertex indices?
}

Answer 1

获取顶点和面索引的简单方法可以像这样完成；

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Surface_mesh<K::Point_3> Mesh;

Mesh sm;

// sm created here or as a result of some CGAL function

std::vector<float> verts;
std::vector<uint32_t> indices;

//Get vertices ...
for (Mesh::Vertex_index vi : sm.vertices()) {
    K::Point_3 pt = sm.point(vi);
    verts.push_back((float)pt.x());
    verts.push_back((float)pt.y());
    verts.push_back((float)pt.z());
}

//Get face indices ...
for (Mesh::Face_index face_index : sm.faces()) {
    CGAL::Vertex_around_face_circulator<Mesh> vcirc(sm.halfedge(face_index), sm), done(vcirc);
    do indices.push_back(*vcirc++); while (vcirc != done);
}

这个例子假设三角形输出(即每 3 个索引描述一个三角形)，尽管正如 Andry 指出的那样，人脸可以有更多的索引。

应添加另一个函数来检查人脸索引计数，如果索引超过 3 个，则将人脸拆分为三角形。