Question

This fails on the ClearRenderTargetView call.
Im not sure where my error is – im following a tutorial and i hvae no clue what is incorrect.
Would appreciate some help, thanks guys!

// DX6.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "DX6.h"
#include <d3d11.h>
#include <d3dx11.h>
#include <d3d10.h>
#include <d3dx9core.h>

// include the Direct3D Library file
#pragma comment (lib, "d3d11.lib")
#pragma comment (lib, "d3dx11.lib")
#pragma comment (lib, "d3dx10.lib")

//forward declares
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
void InitD3D(HWND hWnd);     // sets up and initializes Direct3D
void RenderFrame(void);
void CleanD3D(void);         // closes Direct3D and releases memory

// Global Variables:
HWND hWnd;
HINSTANCE hInst;
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;    // global declaration




int APIENTRY _tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR lpCmdLine,int nCmdShow)
{
    WNDCLASSEX wc;
    ZeroMemory(&wc,sizeof(WNDCLASSEX));
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
    wc.lpszClassName = L"WindowClass1";
    RegisterClassEx(&wc);

    // TODO: Place code here.
    MSG msg={0};

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(L"WindowClass1", L"Test Title", WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return 1;
   }

   ShowWindow(hWnd, nCmdShow);

    // Main message loop:
    while (true)
    {
        if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            // translate keystroke messages into the right format
            TranslateMessage(&msg);

            // send the message to the WindowProc function
            DispatchMessage(&msg);

            // check to see if it's time to quit
            if(msg.message == WM_QUIT)
                break;
        }
        else{
            RenderFrame();
        }
    }

    return (int) msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    PAINTSTRUCT ps;
    HDC hdc;

    switch (message)
    {
    case WM_COMMAND:
        wmId    = LOWORD(wParam);
        wmEvent = HIWORD(wParam);
        // Parse the menu selections:
        switch (wmId)
        {
        case IDM_EXIT:
            DestroyWindow(hWnd);
            break;
        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
        }
        break;
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        // TODO: Add any drawing code here...
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

//D3D
void InitD3D(HWND hWnd){
    DXGI_SWAP_CHAIN_DESC scd;
    ZeroMemory(&scd,sizeof(DXGI_SWAP_CHAIN_DESC));

    scd.BufferCount=1;
    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 = 4;                               // how many multisamples
    scd.Windowed = TRUE;  
    D3D11CreateDeviceAndSwapChain(NULL,D3D_DRIVER_TYPE_HARDWARE,NULL,NULL,NULL,NULL,D3D11_SDK_VERSION,&scd,&swapchain,&dev,NULL,&devcon);

    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);

    //create viewport
    D3D11_VIEWPORT viewport;
    ZeroMemory(&viewport,sizeof(D3D11_VIEWPORT));
    viewport.TopLeftX=0;
    viewport.TopLeftY=0;
    viewport.Width=800;
    viewport.Height=800;

    //set viewport
    devcon->RSSetViewports(1,&viewport);


}
void RenderFrame(void){
    //FAILS HERE!!!
   //Unhandled exception at 0x002e1a9f in DX6.exe: 0xC0000005: Access violation       //reading location 0x00000000.
    devcon->ClearRenderTargetView(backbuffer,D3DXCOLOR(0.0f,0.2f,0.4f,1.0f));

    //switch back & front buffer
    swapchain->Present(0,0);
}

void CleanD3D()
{
    // close and release all existing COM objects
    swapchain->Release();
    dev->Release();
    devcon->Release();
}

Answer 1

You never call InitD3D, so when CreateRenderTargetView is called in RenderFrame the backbuffer has not been set yet.