析构函数被多次调用并且不合适

Question

ma Model 类中的问题在于处理它所组成的每个网格。当它由 7 个网格组成时，首先调用析构函数 21 次。退出程序后，它被调用了 14 次。真的不知道我做错了什么。我能够将问题追溯到这段特定的代码。

void Model::processNode(aiNode *node, const aiScene *scene) {
    for(unsigned int i = 0; i < node->mNumMeshes; i++) {
        aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
        mMeshes.push_back(processMesh(mesh, scene));
    }
    for(unsigned int i = 0; i < node->mNumChildren; i++) {
        processNode(node->mChildren[i], scene);
    }
}

mMeshes 是单个模型对象的网格私有向量。

编辑：

澄清一下，问题是当Mesh类的析构函数没有被注释掉时，它完全破坏了mMeshes向量中的一切。这是Mesh的析构函数

Mesh::~Mesh () {
    glDeleteVertexArrays(1, &mVAO);
    glDeleteBuffers(NUM_BUFFERS, mVBOs);
}

这是网格的向量。

std::vector<Vertex> mVertices;

和processNode的头部，它只是创建新的网格并将其返回给向量。

Mesh Model::processMesh(aiMesh *mesh, const aiScene *scene);

Answer 1

如果您没有在向量中保留足够的内存来容纳新元素，那么向量可以在添加新元素时重新分配内存。在这种情况下，它分配一个新的内存扩展并将所有元素从旧的内存扩展复制到新的内存扩展。因此，将元素复制到新位置后，旧位置的元素将被删除。此外，成员函数push_back 可以处理一个临时对象，该对象将被复制到向量中，之后将被删除。

这是一个演示程序

#include <iostream>
#include <vector>
#include <string>

struct A
{
    std::string s;
    A(const std::string &s) : s(s)
    {
        std::cout << "Object " << this->s << " is created" << std::endl; 
    }

    A( const A &a ) : s( "copy of " + a.s )
    {
        std::cout << "A " << this->s << " is created" << std::endl;
    }

    ~A()
    {
        std::cout << "Object " << s << " is deleted" << std::endl;
    }
};

int main()
{
    {
        std::vector<A> v;

        v.push_back(A("A"));
        v.push_back(A("B"));
        v.push_back(A("C"));
    }
}

它的输出可能看起来像

Object A is created
A copy of A is created
Object A is deleted
Object B is created
A copy of copy of A is created
Object copy of A is deleted
A copy of B is created
Object B is deleted
Object C is created
A copy of copy of copy of A is created
A copy of copy of B is created
Object copy of copy of A is deleted
Object copy of B is deleted
A copy of C is created
Object C is deleted
Object copy of copy of copy of A is deleted
Object copy of copy of B is deleted
Object copy of C is deleted