DIRECTX9 中 CustomVertex 的虚拟析构函数

Tarun 发表于 Dev

塔伦

这是我关于 stackoverflow 的第一个问题，如果我的问题很愚蠢，请原谅我。我想简单地在 Visual Studio 2012 中的 DirectX9 中渲染一个三角形，如下所示：www.directxtutorial.com/Lesson.aspx?lessonid=9-4-4。

当我使用非虚拟析构函数创建 CUSTOMVERTEX 类时，它可以毫无问题地呈现三角形。而如果我将析构函数设为虚拟，则不会呈现三角形。

这是带有虚拟析构函数的代码：

// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>

// define the screen resolution
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600

// include the Direct3D Library file
#pragma comment (lib, "d3d9.lib")

#define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 v_buffer = NULL;    // the pointer to the vertex buffer

// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations
// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);



//************CUSTOMVERTEX CLASS**********/
class CUSTOMVERTEX {
public:
    CUSTOMVERTEX( float _X, float _Y, float _Z, float _RHW, DWORD _COLOR )
        : X(_X), Y(_Y), Z(_Z), RHW(_RHW), COLOR(_COLOR)
    {}

    virtual ~CUSTOMVERTEX(){
        OutputDebugString("Destructed!!!\n");
    }
    float X, Y, Z, RHW;
    DWORD COLOR;
};

// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = "WindowClass";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL,
                          "WindowClass",
                          "Our Direct3D Program",
                          WS_OVERLAPPEDWINDOW,
                          0, 0,
                          SCREEN_WIDTH, SCREEN_HEIGHT,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    ShowWindow(hWnd, nCmdShow);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        if(msg.message == WM_QUIT)
            break;

        render_frame();
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

    return DefWindowProc (hWnd, message, wParam, lParam);
}


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;

    // create a device class using this information and the info from the d3dpp struct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the triangle
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

        // select which vertex format we are using
        d3ddev->SetFVF(CUSTOMFVF);

        // select the vertex buffer to display
        d3ddev->SetStreamSource(0, v_buffer, 0, sizeof(CUSTOMVERTEX));

        // copy the vertex buffer to the back buffer
        d3ddev->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);

    d3ddev->EndScene();

    d3ddev->Present(NULL, NULL, NULL, NULL);
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    v_buffer->Release();    // close and release the vertex buffer
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    // create the vertices using the CUSTOMVERTEX class
    CUSTOMVERTEX vertices[] =
    {
        CUSTOMVERTEX(400.0f, 62.5f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255)),
        CUSTOMVERTEX(650.0f, 500.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0)),
        CUSTOMVERTEX(150.0f, 500.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0)),
    };

    // create a vertex buffer interface called v_buffer
    d3ddev->CreateVertexBuffer(3*sizeof(CUSTOMVERTEX),
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &v_buffer,
                               NULL);

    VOID* pVoid;    // a void pointer

    // lock v_buffer and load the vertices into it
    v_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, vertices, sizeof(vertices));
    v_buffer->Unlock();
}

渲染三角形：渲染三角形

没有虚拟析构函数的代码：

// include the basic windows header files and the Direct3D header file
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>

// define the screen resolution
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600

// include the Direct3D Library file
#pragma comment (lib, "d3d9.lib")

#define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 v_buffer = NULL;    // the pointer to the vertex buffer

// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations
// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);



//************CUSTOMVERTEX CLASS**********/
class CUSTOMVERTEX {
public:
    CUSTOMVERTEX( float _X, float _Y, float _Z, float _RHW, DWORD _COLOR )
        : X(_X), Y(_Y), Z(_Z), RHW(_RHW), COLOR(_COLOR)
    {}

    ~CUSTOMVERTEX(){
        OutputDebugString("Destructed!!!\n");
    }
    float X, Y, Z, RHW;
    DWORD COLOR;
};

// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.lpszClassName = "WindowClass";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL,
                          "WindowClass",
                          "Our Direct3D Program",
                          WS_OVERLAPPEDWINDOW,
                          0, 0,
                          SCREEN_WIDTH, SCREEN_HEIGHT,
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    ShowWindow(hWnd, nCmdShow);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        if(msg.message == WM_QUIT)
            break;

        render_frame();
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

    return DefWindowProc (hWnd, message, wParam, lParam);
}


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;

    // create a device class using this information and the info from the d3dpp struct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the triangle
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

        // select which vertex format we are using
        d3ddev->SetFVF(CUSTOMFVF);

        // select the vertex buffer to display
        d3ddev->SetStreamSource(0, v_buffer, 0, sizeof(CUSTOMVERTEX));

        // copy the vertex buffer to the back buffer
        d3ddev->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);

    d3ddev->EndScene();

    d3ddev->Present(NULL, NULL, NULL, NULL);
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    v_buffer->Release();    // close and release the vertex buffer
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    // create the vertices using the CUSTOMVERTEX class
    CUSTOMVERTEX vertices[] =
    {
        CUSTOMVERTEX(400.0f, 62.5f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255)),
        CUSTOMVERTEX(650.0f, 500.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0)),
        CUSTOMVERTEX(150.0f, 500.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0)),
    };

    // create a vertex buffer interface called v_buffer
    d3ddev->CreateVertexBuffer(3*sizeof(CUSTOMVERTEX),
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &v_buffer,
                               NULL);

    VOID* pVoid;    // a void pointer

    // lock v_buffer and load the vertices into it
    v_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, vertices, sizeof(vertices));
    v_buffer->Unlock();
}

没有任何三角形渲染：没有任何三角形

任何人都可以向我解释为什么会发生这种情况吗？

查克·沃尔伯恩

简而言之：添加virtual更改结构的内存布局，这意味着您的数据不再位于您提供的顶点声明的正确位置：

struct CUSTOMVERTEX {
    CUSTOMVERTEX( float _X, float _Y, float _Z, float _RHW, DWORD _COLOR )
        : X(_X), Y(_Y), Z(_Z), RHW(_RHW), COLOR(_COLOR)
    {}

    float X, Y, Z, RHW;
    DWORD COLOR;
};

该结构的大小为 20 字节。

class CUSTOMVERTEX {
public:
    CUSTOMVERTEX( float _X, float _Y, float _Z, float _RHW, DWORD _COLOR )
        : X(_X), Y(_Y), Z(_Z), RHW(_RHW), COLOR(_COLOR)
    {}

    virtual ~CUSTOMVERTEX(){
        OutputDebugString("Destructed!!!\n");
    }
    float X, Y, Z, RHW;
    DWORD COLOR;
};

此结构的大小对于 x86 (Win32) 为 24 字节，对于 x64 本机为 32 字节。这是因为在结构的开头添加了一个指向 vtable 的指针（在 x64 上，额外的填充将其推出多于 8 个字节）。

此外，由于您通过 Direct3D 顶点缓冲区使用该类型，因此永远不会执行它的构造函数或析构函数。它只是从堆中分配为“普通旧数据类型”。唯一的一次构造或析构函数被调用用于堆分配内存是通过new，new []，delete，和/或delete []。内部 Direct3D 顶点缓冲区正在做一些更类似于malloc.

当您创建初始化数组时vertices，C++ 编译器会调用您的构造函数，并在vertices超出范围时调用析构函数。

换句话说：这并不像你认为的那样。不要virtual在你的顶点数据结构中使用。

请注意，您应该考虑使用智能指针Microsoft::WRL::ComPtr来管理 Direct3D COM 对象的生命周期。这利用了构造函数/析构函数的 C++ 范围规则来正确Release自动调用。当然，您也不应该花大量时间学习旧版 Direc3D 9。

本文收集自互联网，转载请注明来源。

如有侵权，请联系 [email protected] 删除。

编辑于 2021-06-8

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