为什么我的索引生成函数不能正确构建三角形基元？

问：

我正在尝试编写一个函数，该函数会自动填充网格的索引向量容器。从理论上讲，该函数应该可以毫无问题地工作，因为它会以正确的顺序生成适当的索引;但是，三角形不会形成！相反，我只剩下一行。

我的网格生成代码应该构建一个八面体，然后在主游戏循环中渲染它。网格类完整如下所示：

struct vertex
{
    glm::vec3 position;
    glm::vec3 color;
};

class Mesh
{
public:
    GLuint VAO, VBO, EBO;
    std::vector <vertex> vtx;
    std::vector <glm::vec3> idx;
    glm::mat4 modelMatrix = glm::mat4(1.f); 

    Mesh(glm::vec3 position, glm::vec3 scale)
    {
        vertexGen(6);
        idx = indexGen(6);
        modelMatrix = glm::scale(glm::translate(modelMatrix, position), scale);
        initMesh();
    };
    void Render(Shader shaderProgram, Camera camera, bool wireframe)
    {
        glUseProgram(shaderProgram.ID);
        glPatchParameteri(GL_PATCH_VERTICES, 3); // Indicates to the VAO that each group of three vertices is one patch (triangles)
        glProgramUniformMatrix4fv(shaderProgram.ID, 0, 1, GL_FALSE, glm::value_ptr(modelMatrix));
        glProgramUniformMatrix4fv(shaderProgram.ID, 1, 1, GL_FALSE, glm::value_ptr(camera.camMatrix));
        glProgramUniform3fv(shaderProgram.ID, 2, 1, glm::value_ptr(camera.Position));

        glBindVertexArray(VAO); // Binds the VAO to the shader program
        if (wireframe)
        {
            glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
            glDisable(GL_CULL_FACE);
        }
        else
        {
            glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
            //glEnable(GL_CULL_FACE);
        }
        glDrawElements(GL_PATCHES, idx.size(), GL_UNSIGNED_INT, 0); // Tells the shader program how to draw the primitives
    }
private:
    void vertexGen(int n) {
        // Populate the base six vertices
        vtx.push_back(vertex{ glm::vec3( 0.0f, 0.5f,  0.0f), glm::vec3(0.f, 1.f, 0.f) });
        vtx.push_back(vertex{ glm::vec3(-0.5f, 0.0f,  0.0f), glm::vec3(0.f, 1.f, 0.f) });
        vtx.push_back(vertex{ glm::vec3( 0.0f, 0.0f, -0.5f), glm::vec3(0.f, 1.f, 0.f) });
        vtx.push_back(vertex{ glm::vec3( 0.5f, 0.0f,  0.0f), glm::vec3(0.f, 1.f, 0.f) });
        vtx.push_back(vertex{ glm::vec3( 0.0f, 0.0f,  0.5f), glm::vec3(0.f, 1.f, 0.f) });
        vtx.push_back(vertex{ glm::vec3( 0.0f,-0.5f,  0.0f), glm::vec3(0.f, 1.f, 0.f) });
    }
    std::vector<glm::vec3> indexGen(int n) {
        std::vector<glm::vec3> indices;

        // Calculate the indices for the top 4 triangles
        indices.push_back(glm::vec3( 0, n - 5, n - 4 ));
        indices.push_back(glm::vec3( 0, n - 4, n - 3 ));
        indices.push_back(glm::vec3( 0, n - 3, n - 2 ));
        indices.push_back(glm::vec3( 0, n - 2, n - 5 ));

        // Calculate the indices for the bottom 4 triangles
        indices.push_back(glm::vec3( 5, n - 5, n - 4)); 
        indices.push_back(glm::vec3( 5, n - 4, n - 3));
        indices.push_back(glm::vec3( 5, n - 3, n - 2));
        indices.push_back(glm::vec3( 5, n - 2, n - 5));

        return indices;
    }
    void initMesh()
    {
        glCreateVertexArrays(1, &VAO); // Sets the address of the uint VAO as the location of a gl vertex array object
        glCreateBuffers(1, &VBO);      // Sets the address of the uint VBO as the location of a gl buffer object
        glCreateBuffers(1, &EBO);      // Sets the address of the uint EBO as the location of a gl buffer object

        glNamedBufferData(VBO, vtx.size() * sizeof(vtx[0]), vtx.data(), GL_STATIC_DRAW); // Sets the data of the buffer named VBO
        glNamedBufferData(EBO, idx.size() * sizeof(idx[0]), idx.data(), GL_STATIC_DRAW); // Sets the data of the buffer named EBO

        glEnableVertexArrayAttrib(VAO, 0); // Enables an attribute of the VAO in location 0
        glEnableVertexArrayAttrib(VAO, 1); // Enables an attribute of the VAO in location 1

        glVertexArrayAttribBinding(VAO, 0, 0); // Layout Location of Position Vectors
        glVertexArrayAttribBinding(VAO, 1, 0); // Layout Location of Color Values

        glVertexArrayAttribFormat(VAO, 0, 3, GL_FLOAT, GL_FALSE, 0); // Size, and Type of Position Vectors
        glVertexArrayAttribFormat(VAO, 1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat)); // For the Color Values

        glVertexArrayVertexBuffer(VAO, 0, VBO, 0, 6 * sizeof(GLfloat)); // Sets the VBO to indicate the start, offset, and stride of vertex data in the VAO

        glVertexArrayElementBuffer(VAO, EBO); // Sets the EBO to index the VAO vertex connections
    }
};

我一步一步地回答了这个问题，并在纸上完成了所有的基本数学运算。索引生成函数以正确的顺序返回预期的索引，就像只写出索引一样，但它的不同之处在于，写出的索引生成所需的结果，而生成函数在呈现时只生成一行：

我怀疑问题出在我的网格初始化函数 （initMesh） 上，特别是在 glNamedBufferData 或 glVertexArrayVertexBuffer 中，但我对这些函数的了解非常有限。我尝试将 glNamedBufferData 函数的参数更改为 idx.size（）*sizeof（idx[0].x） 的不同变体，但这产生了相同的结果，所以我不知所措。有人可以帮我解决这个问题吗？