简单的DirectX 11程序运行时错误

我是DirectX 11的新手，我已经设法在我的书中获得了绘图三角形章节。我已经写了这段代码，但我得到一个运行时错误:" DirectX 11.exe中0x00cd14e6的未处理异常:0xc0000005:访问违反读取位置0x00000000。"

我的编译器显示错误是在InitPipeline函数，但我在那里找不到错误。我做错了什么?

    #include <windows.h>
#include <windowsx.h>
#include <d3d11.h>
#include <D3DX11.h>
#include <D3DX10.h>
#pragma comment(lib,"d3d11.lib")
#pragma comment(lib,"d3dx11.lib")
#pragma comment(lib,"d3dx10.lib")
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600
IDXGISwapChain                  *swapchain;
ID3D11Device                    *dev;
ID3D11DeviceContext             *devcon;
ID3D11InputLayout               *pInputLayout;
ID3D11Buffer                    *pVBuffer;
ID3D11RenderTargetView          *backbuffer;
ID3D11VertexShader              *pVS;
ID3D11PixelShader               *pPS;
// Type
struct VERTEX
{
    FLOAT X,Y,Z;
    D3DXCOLOR Color;
};
//DirectX
void InitPipeline()
{
    // load and compile the two shaders
     ID3D10Blob *VS, *PS;
     D3DX11CompileFromFile("shaders.hlsl", 0, 0, "VShader", "vs_5_0", 0, 0, 0, &VS, 0, 0);
     D3DX11CompileFromFile("shaders.hlsl", 0, 0, "PShader", "ps_5_0", 0, 0, 0, &PS, 0, 0);
     //debug
     if(!dev)
     {
         MessageBox(NULL, "DEV = NULL", "ERROR", NULL);
     }
     if(!devcon)
     {
         MessageBox(NULL, "DEVCON = NULL", "ERROR", NULL);
     }
     if(!VS)
     {
         MessageBox(NULL, "VS = NULL", "ERROR", NULL);
     }
     if(!PS)
     {
         MessageBox(NULL, "PS = NULL", "ERROR", NULL);
     }
     // encapsulate both shaders into shader objects
     dev->CreateVertexShader(VS->GetBufferPointer(), VS->GetBufferSize(), NULL, &pVS);
     dev->CreatePixelShader(PS->GetBufferPointer(), PS->GetBufferSize(), NULL, &pPS);
     // set the shader objects
     devcon->VSSetShader(pVS, 0, 0);
     devcon->PSSetShader(pPS, 0, 0);
    D3D11_INPUT_ELEMENT_DESC ied[] =
    {
        {"POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0,0,D3D11_INPUT_PER_VERTEX_DATA,0},
        {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT,0,D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0},
    };
    dev->CreateInputLayout(ied, 2, VS->GetBufferPointer(), VS->GetBufferSize(), &pInputLayout);
    devcon->IASetInputLayout(pInputLayout);
}

void InitGraphics()
{
    VERTEX OurVertices[] =
    {
        {1,0,0,D3DXCOLOR(1,0,0,1)},
        {0,-1,0,D3DXCOLOR(1,0,0,1)},
        {0,0,1,D3DXCOLOR(1,0,0,1)},
    };
    D3D11_BUFFER_DESC bd;
    ZeroMemory(&bd, sizeof(D3D11_BUFFER_DESC));
    bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    bd.ByteWidth = sizeof(VERTEX)*3;
    bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
    bd.Usage = D3D11_USAGE_DYNAMIC;
    dev->CreateBuffer(&bd, NULL, &pVBuffer);
    D3D11_MAPPED_SUBRESOURCE ms;
    devcon->Map(pVBuffer, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &ms);
    memcpy(ms.pData, OurVertices, sizeof(OurVertices));
    devcon->Unmap(pVBuffer, NULL);
}
void RenderFrame()
{
    devcon->ClearRenderTargetView(backbuffer, D3DXCOLOR(0,0,1,1));
    UINT stride = sizeof(VERTEX);
    UINT offset = 0;
    devcon->IASetVertexBuffers(0, 1, &pVBuffer, &stride, &offset);
    devcon->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
    devcon->Draw(3,0);
    swapchain->Present(0,0);
}
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.BufferDesc.Width = SCREEN_WIDTH;                   // set the back buffer width
     scd.BufferDesc.Height = SCREEN_HEIGHT;                 // set the back buffer height
     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 = 4;                              // how many multisamples
     scd.Windowed = TRUE;                                   // windowed/full-screen mode
     scd.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;    // allow full-screen switching
     // create a device, device context and swap chain using the information in the scd struct
     if(FAILED(D3D11CreateDeviceAndSwapChain(NULL,
                                   D3D_DRIVER_TYPE_HARDWARE,
                                   NULL,
                                   NULL,
                                   NULL,
                                   NULL,
                                   D3D11_SDK_VERSION,
                                   &scd,
                                   &swapchain,
                                   &dev,
                                   NULL,
                                   &devcon)))
     {
         MessageBox(NULL, "D3D11CreateDeviceAndSwapChain Failed", "ERROR", NULL);
     }


     // 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 = SCREEN_WIDTH;
     viewport.Height = SCREEN_HEIGHT;
     devcon->RSSetViewports(1, &viewport);
    InitPipeline();
     InitGraphics();
 }
void CleanD3D()
{
    swapchain->SetFullscreenState(FALSE, NULL);
    dev->Release();
    devcon->Release();
    swapchain->Release();
    pInputLayout->Release();
    pVBuffer->Release();
    backbuffer->Release();
    pVS->Release();
    pPS->Release();
}
// Window
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
}
INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, INT nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;
    ZeroMemory(&wc, sizeof(WNDCLASSEX));
    wc.cbSize = sizeof(WNDCLASSEX);
    //wc.hbrBackground = (HBRUSH)GetStockObject(GRAY_BRUSH);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hIcon = (HICON)LoadIcon(NULL, IDI_APPLICATION);
    wc.hInstance = hInstance;
    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = "DirectXWindow";
    wc.style = CS_HREDRAW | CS_VREDRAW;
    RegisterClassEx(&wc);
    hWnd = CreateWindowEx(NULL,
        "DirectXWindow",
        "DirectX 11 (June 2010",
        WS_OVERLAPPEDWINDOW,
        0,0,
        SCREEN_WIDTH, SCREEN_HEIGHT,
        NULL,
        NULL,
        hInstance,
        NULL);
    ShowWindow(hWnd, nCmdShow);
    InitD3D(hWnd);
    UpdateWindow(hWnd);
    MSG msg = {0};
    while(msg.message != WM_QUIT)
    {
        if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        else
        {
            RenderFrame();
        }
    }
    CleanD3D();
    return msg.wParam;
}