Question

ma Model类中的问题是处理由它组成的每个网格。当它由7个网格组成时，首先将析构函数调用21次。退出该计划后，它被召唤了14次。真的不知道我做错了什么。我能够将问题拖到这个特定的代码片段中。

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Model对象的网格的私有向量。

编辑：

澄清一下，问题是当Mesh类的析构函数没有被注释掉时，它会完全破坏mMeshes向量中的所有内容。这是Mesh

的析构函数

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

这是Meshes的载体。

std::vector<Vertex> mVertices;

和processNode的标题，它只是创建新的网格物体并将其返回到矢量。

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

Answer 1

如果在向量中没有保留足够的内存来容纳新元素，则向量可以在添加新元素时重新分配内存。在这种情况下，它会分配一个新的内存扩展，并将旧内存区域中的所有元素复制到新内存中。因此，在将元素复制到新位置之后，将删除旧位置中的元素。成员函数push_back也可以处理将被复制到向量的临时对象，之后将被删除。

这是一个示范程序

#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

析构函数被多次调用并且不合适

1 个答案: