[英]Read access violation. _Mycont was nullptr error while getting udp data into vectors in C++
[英]C++ Directx Error: Access Violation, swapchain was nullptr
我正在嘗試使用DirectX學習3D繪圖,並且在教程中獲得了此代碼,但是每次嘗試對其進行編譯時,我的編譯器都會出現“訪問沖突swapchain was nullptr”錯誤。
提前致謝
// include the basic windows header files and the Direct3D header files
#include <windows.h>
#include <windowsx.h>
#include <d3d11.h>
#include <d3dx11.h>
#include <d3dx10.h>
// include the Direct3D Library file
#pragma comment (lib, "d3d11.lib")
#pragma comment (lib, "d3dx11.lib")
#pragma comment (lib, "d3dx10.lib")
// global declarations
IDXGISwapChain *swapchain; // the pointer to the swap chain interface
ID3D11Device *dev; // the pointer to our Direct3D device interface
ID3D11DeviceContext *devcon; // the pointer to our Direct3D device context
ID3D11RenderTargetView *backbuffer; // the pointer to our back buffer
// function prototypes
void InitD3D(HWND hWnd); // sets up and initializes Direct3D
void RenderFrame(void); // renders a single frame
void CleanD3D(void); // closes Direct3D and releases memory
// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
// 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.hbrBackground = (HBRUSH)COLOR_WINDOW;
wc.lpszClassName = L"WindowClass";
RegisterClassEx(&wc);
RECT wr = {0, 0, 800, 600};
AdjustWindowRect(&wr, WS_OVERLAPPEDWINDOW, FALSE);
hWnd = CreateWindowEx(NULL,
L"WindowClass",
L"Our First Direct3D Program",
WS_OVERLAPPEDWINDOW,
300,
300,
wr.right - wr.left,
wr.bottom - wr.top,
NULL,
NULL,
hInstance,
NULL);
ShowWindow(hWnd, nCmdShow);
// set up and initialize Direct3D
InitD3D(hWnd);
// enter the main loop:
MSG msg;
while(TRUE)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
if(msg.message == WM_QUIT)
break;
}
RenderFrame();
}
// 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)
{
// create a struct to hold information about the swap chain
DXGI_SWAP_CHAIN_DESC scd;
// clear out the struct for use
ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC));
// fill the swap chain description struct
scd.BufferCount = 1; // one back buffer
scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; // use 32-bit color
scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; // how swap chain is to be used
scd.OutputWindow = hWnd; // the window to be used
scd.SampleDesc.Count = 1; // how many multisamples
scd.SampleDesc.Quality = 0; // multisample quality level
scd.Windowed = TRUE; // windowed/full-screen mode
// create a device, device context and swap chain using the information in the scd struct
D3D11CreateDeviceAndSwapChain(NULL,
D3D_DRIVER_TYPE_HARDWARE,
NULL,
NULL,
NULL,
NULL,
D3D11_SDK_VERSION,
&scd,
&swapchain,
&dev,
NULL,
&devcon);
// get the address of the back buffer
ID3D11Texture2D *pBackBuffer;
swapchain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer);
// use the back buffer address to create the render target
dev->CreateRenderTargetView(pBackBuffer, NULL, &backbuffer);
pBackBuffer->Release();
// set the render target as the back buffer
devcon->OMSetRenderTargets(1, &backbuffer, NULL);
// Set the viewport
D3D11_VIEWPORT viewport;
ZeroMemory(&viewport, sizeof(D3D11_VIEWPORT));
viewport.TopLeftX = 0;
viewport.TopLeftY = 0;
viewport.Width = 800;
viewport.Height = 600;
devcon->RSSetViewports(1, &viewport);
}
// this is the function used to render a single frame
void RenderFrame(void)
{
// clear the back buffer to a deep blue
devcon->ClearRenderTargetView(backbuffer, D3DXCOLOR(0.0f, 0.2f, 0.4f, 1.0f));
// do 3D rendering on the back buffer here
// switch the back buffer and the front buffer
swapchain->Present(0, 0);
}
// this is the function that cleans up Direct3D and COM
void CleanD3D(void)
{
// close and release all existing COM objects
swapchain->Release();
backbuffer->Release();
dev->Release();
devcon->Release();
}
當像Direct3D一樣對COM AP進行編程時,檢查返回HRESULT
的所有函數的返回值至關重要。 如果可以安全地忽略返回值,則它將返回void
。
這意味着在每個HRESULT上使用SUCCEEDED
或FAILED
宏。 您應該避免執行== S_OK
或!= S_OK
因為除了S_OK
之外還有成功的結果。 使用現代C ++,更好的選擇是將ThrowIfFailed用於“致命的快速失敗”方案,在這種情況下程序無法從失敗中恢復。
您的代碼也無法檢查對RegisterClassEx
或CreateWindowEx
的調用是否失敗,這可能會導致hWnd
在您真正開始之前為null。
您還應該考慮使用
nullptr
而不是NULL
。 您正在實際使用UINT
位置傳遞NULL
,因為您使用的是老式的預處理器定義0,所以該位置只能編譯。
一旦檢查了返回值,下一步就是啟用調試設備。 請參見Direct3D剖析11創建設備和Direct3D SDK調試層技巧 。 當返回諸如E_INVALIDARG
常見故障時,調試層將在調試輸出窗口中提供其他信息。
請注意, BufferCount
必須至少為2。無論如何,低於1的值都將被視為2。
由於您是Direct3D 11編程的新手,因此建議您看一下DirectX Tool Kit教程 。
您還應該初始化所有變量。
IDXGISwapChain *swapchain = nullptr;
ID3D11Device *dev = nullptr;
ID3D11DeviceContext *devcon = nullptr;
ID3D11RenderTargetView *backbuffer = nullptr;
您應該真正避免對COM對象使用“原始”指針。 更好的選擇是使用ComPtr之類的COM智能指針。
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