ID3D11Factory instead of ID3D11Factory1

[matt77hias]

While integrating the current version of ImGui, I kept failing the following assert of ImGui::NewFrame in my application:

IM_ASSERT(g.IO.Fonts->Fonts.Size > 0 && "Font Atlas not built. Did you call io.Fonts >GetTexDataAsRGBA32() / GetTexDataAsAlpha8() ?");

However, the actual cause is not directly related to fonts and font atlases, but rather to ImGui's provided D3D11 bindings. In the code below, the first two if conditions are true and the third one is false, resulting in no device, device context and factory bindings. This is the case for my application, but not for the demo application provided with ImGui.

bool    ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_context)
{
    // Get factory from device
    IDXGIDevice* pDXGIDevice = NULL;
    IDXGIAdapter* pDXGIAdapter = NULL;
    IDXGIFactory1* pFactory = NULL;

    if (device->QueryInterface(IID_PPV_ARGS(&pDXGIDevice)) == S_OK) // true
        if (pDXGIDevice->GetParent(IID_PPV_ARGS(&pDXGIAdapter)) == S_OK) // true
            if (pDXGIAdapter->GetParent(IID_PPV_ARGS(&pFactory)) == S_OK) // false
            {
                g_pd3dDevice = device;
                g_pd3dDeviceContext = device_context;
                g_pFactory = pFactory;
            }
    if (pDXGIDevice) pDXGIDevice->Release();
    if (pDXGIAdapter) pDXGIAdapter->Release();

    return true;
}

For obtaining a device and device context in my application, I go the other way around and start with a IDXGIFactory (whereas ImGui does use the default IDXGIAdapter).

When I replace both occurrences of IDXGIFactory1 with IDXGIFactory in imgui_impl_dx11.cpp, both my application and the provided demo application work correctly. This change is handled by this pull request. (Apparently, ImGui's provided D3D11 bindings do not really use the global variable g_pFactory at all. So I am not sure why there is such a variable in the first place and why it needs to be of type IDXGIFactory1?)

[ocornut]

Thanks @matt77hias this is merged. You are right this isn't used in master branch. The factory is used in the viewport branch and I have merged this part earlier in master with the intention of testing it, so your report is helpful.