DirectX 11: Runtime crash when running simple DirectX application - c++

Question

I've attempted to inherit some public globals from a base class and successfully got the window up and running and initialized directx similarly in a simple way- in it's own class, inheriting globals, such as HWND hWnd.
However when the program is run, D3D11CreateDeviceAndSwapChain() fails. On further inspection, debugger gives:
DXGI ERROR: IDXGIFactory::CreateSwapChain: No target window specified in DXGI_SWAP_CHAIN_DESC, and no window associated with owning factory. [ MISCELLANEOUS ERROR #6: ]
The DXGI_SWAP_CHAIN_DESC structure is as follows:
SwapChainDesc.BufferCount = 1;
SwapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
SwapChainDesc.BufferDesc.Width = 1024;
SwapChainDesc.BufferDesc.Height = 768;
SwapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
SwapChainDesc.OutputWindow = hWnd;
SwapChainDesc.BufferDesc.RefreshRate.Numerator = 60;
SwapChainDesc.BufferDesc.RefreshRate.Denominator = 1;
SwapChainDesc.SampleDesc.Count = 4;
SwapChainDesc.Windowed = TRUE;
SwapChainDesc.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;
Where hWnd is stored in:
class Infinity{
public:
Infinity();
~Infinity();
HWND hWnd;
};
And inherited as such:
class Direct3D : public Infinity{
public:
Direct3D();
~Direct3D();
IDXGISwapChain *Swapchain; //Display modes.
ID3D11Device *Device;
ID3D11DeviceContext *DeviceContext;
ID3D11RenderTargetView *RenderTargetView;
void D3D_Start(int width, int height);
void D3D_Render();
void D3D_Terminate();
}Direct3D;
Checked the value for SwapChainDesc.OutputWindow = hWnd; at runtime and it's null. (0x00000000) and I think that's what is causing Swapchain->GetBuffer to fail, since D3D11CreateDeviceAndSwapChain needs a working HWND. If this is true, Why is ShowWindow() successful?
Edit: I should also add that ShowWindow()is in a similar class inheriting from class Infinity:
class Windows : public Infinity{
public:
Windows();
~Windows();
bool DisplayWindow(int width, int height, HINSTANCE hInstance);
static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
}Windows;

Answer 1

Observe the following code:
class A {
public:
int memA;
static int memB;
};
int A::memB = 0;
class B : public A {};
class C : public A {};
int main() {
A a;
B b;
C c;
a.memA = 4;
b.memA = 5;
c.memA = 6;
A::memB = 4;
B::memB = 5;
C::memB = 6;
printf("a.memA = %d\n", a.memA);
printf("b.memA = %d\n", b.memA);
printf("c.memA = %d\n", c.memA);
printf("A::memB = %d\n", A::memB);
printf("B::memB = %d\n", B::memB);
printf("C::memB = %d\n", C::memB);
return 0;
}
The output of this code is:
a.memA = 4
b.memA = 5
c.memA = 6
A::memB = 6
B::memB = 6
C::memB = 6
By making a member static, you ensure that: A) There is only ever one instance of that member and B) All child classes have direct access to that member (assuming it isn't private). Your hWnd is not global as your code is written, however making it static will accomplish what you want.
The following code does this:
//header file
class Infinity {
public:
static HWND hWnd;
};
//cpp file
HWND Infinity::hWnd = NULL;
Your Direct3D class will be able to access the non-null hWnd written to by your Window class. This is only a valid solution if you intend to create one window - otherwise, you will have to resort to a more complicated parent-child relationship between the two classes (probably without using inheritance).