#include "pch.h"
#include "Direct3DBase.h"

using namespace Microsoft::WRL;
using namespace Windows::UI::Core;
using namespace Windows::Foundation;

// Constructor.
Direct3DBase::Direct3DBase()
{
}

// Initialize the Direct3D resources required to run.
void Direct3DBase::Initialize(CoreWindow^ window)
{
    m_window = window;
    
    CreateDeviceResources();
    CreateWindowSizeDependentResources();
}

// These are the resources that depend on the device.
void Direct3DBase::CreateDeviceResources()
{
    // This flag adds support for surfaces with a different color channel ordering than the API default.
    // It is recommended usage, and is required for compatibility with Direct2D.
    UINT creationFlags = D3D11_CREATE_DEVICE_BGRA_SUPPORT;

#if defined(_DEBUG)
    // If the project is in a debug build, enable debugging via SDK Layers with this flag.
    creationFlags |= D3D11_CREATE_DEVICE_DEBUG;
#endif

    // This array defines the set of DirectX hardware feature levels this app will support.
    // Note the ordering should be preserved.
    // Don't forget to declare your application's minimum required feature level in its
    // description.  All applications are assumed to support 9.1 unless otherwise stated.
    D3D_FEATURE_LEVEL featureLevels[] = 
    {
        D3D_FEATURE_LEVEL_11_1,
        D3D_FEATURE_LEVEL_11_0,
        D3D_FEATURE_LEVEL_10_1,
        D3D_FEATURE_LEVEL_10_0,
        D3D_FEATURE_LEVEL_9_3,
        D3D_FEATURE_LEVEL_9_2,
        D3D_FEATURE_LEVEL_9_1
    };

    // Create the DX11 API device object, and get a corresponding context.
    ComPtr<ID3D11Device> device;
    ComPtr<ID3D11DeviceContext> context;
    DX::ThrowIfFailed(
        D3D11CreateDevice(
            nullptr,                    // specify null to use the default adapter
            D3D_DRIVER_TYPE_HARDWARE,
            nullptr,                    // leave as nullptr unless software device
            creationFlags,              // optionally set debug and Direct2D compatibility flags
            featureLevels,              // list of feature levels this app can support
            ARRAYSIZE(featureLevels),   // number of entries in above list
            D3D11_SDK_VERSION,          // always set this to D3D11_SDK_VERSION
            &device,                    // returns the Direct3D device created
            &m_featureLevel,            // returns feature level of device created
            &context                    // returns the device immediate context
            )
        );

    // Get the DirectX11.1 device by QI off the DirectX11 one.
    DX::ThrowIfFailed(
        device.As(&m_d3dDevice)
        );

    // And get the corresponding device context in the same way.
    DX::ThrowIfFailed(
        context.As(&m_d3dContext)
        );
}

// Allocate all memory resources that change on a window SizeChanged event.
void Direct3DBase::CreateWindowSizeDependentResources()
{ 
    // Store the window bounds so the next time we get a SizeChanged event we can
    // avoid rebuilding everything if the size is identical.
    m_windowBounds = m_window->Bounds;

    // If the swap chain already exists, resize it.
    if(m_swapChain != nullptr)
    {
        DX::ThrowIfFailed(
            m_swapChain->ResizeBuffers(2, 0, 0, DXGI_FORMAT_B8G8R8A8_UNORM, 0)
            );
    }
    // Otherwise, create a new one.
    else
    {
        // Create a descriptor for the swap chain.
        DXGI_SWAP_CHAIN_DESC1 swapChainDesc = {0};
        swapChainDesc.Width = 0;                                     // use automatic sizing
        swapChainDesc.Height = 0;
        swapChainDesc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;           // this is the most common swapchain format
        swapChainDesc.Stereo = false; 
        swapChainDesc.SampleDesc.Count = 1;                          // don't use multi-sampling
        swapChainDesc.SampleDesc.Quality = 0;
        swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
        swapChainDesc.BufferCount = 2;                               // use two buffers to enable flip effect
        swapChainDesc.Scaling = DXGI_SCALING_NONE;
        swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL; // we recommend using this swap effect for all applications
        swapChainDesc.Flags = 0;

        // Once the desired swap chain description is configured, it must be created on the same adapter as our D3D Device

        // First, retrieve the underlying DXGI Device from the D3D Device
        ComPtr<IDXGIDevice1>  dxgiDevice;
        DX::ThrowIfFailed(
            m_d3dDevice.As(&dxgiDevice)
            );

        // Identify the physical adapter (GPU or card) this device is running on.
        ComPtr<IDXGIAdapter> dxgiAdapter;
        DX::ThrowIfFailed(
            dxgiDevice->GetAdapter(&dxgiAdapter)
            );

        // And obtain the factory object that created it.
        ComPtr<IDXGIFactory2> dxgiFactory;
        DX::ThrowIfFailed(
            dxgiAdapter->GetParent(
                __uuidof(IDXGIFactory2), 
                &dxgiFactory
                )
            );

		Windows::UI::Core::CoreWindow^ p = m_window.Get();

        // Create a swap chain for this window from the DXGI factory.
        DX::ThrowIfFailed(
            dxgiFactory->CreateSwapChainForCoreWindow(
                m_d3dDevice.Get(),
                reinterpret_cast<IUnknown*>(p),
                &swapChainDesc,
                nullptr,    // allow on all displays
                &m_swapChain
                )
            );
            
        // Ensure that DXGI does not queue more than one frame at a time. This both reduces 
        // latency and ensures that the application will only render after each VSync, minimizing 
        // power consumption.
        DX::ThrowIfFailed(
            dxgiDevice->SetMaximumFrameLatency(1)
            );
    }
    
    // Obtain the backbuffer for this window which will be the final 3D rendertarget.
    ComPtr<ID3D11Texture2D> backBuffer;
    DX::ThrowIfFailed(
        m_swapChain->GetBuffer(
            0,
            __uuidof(ID3D11Texture2D),
            &backBuffer
            )
        );

    // Create a view interface on the rendertarget to use on bind.
    DX::ThrowIfFailed(
        m_d3dDevice->CreateRenderTargetView(
            backBuffer.Get(),
            nullptr,
            &m_renderTargetView
            )
        );

    // Cache the rendertarget dimensions in our helper class for convenient use.
    D3D11_TEXTURE2D_DESC backBufferDesc;
    backBuffer->GetDesc(&backBufferDesc);
    m_renderTargetSize.Width  = static_cast<float>(backBufferDesc.Width);
    m_renderTargetSize.Height = static_cast<float>(backBufferDesc.Height);

    // Create a descriptor for the depth/stencil buffer.
    CD3D11_TEXTURE2D_DESC depthStencilDesc(
        DXGI_FORMAT_D24_UNORM_S8_UINT, 
        backBufferDesc.Width,
        backBufferDesc.Height,
        1,
        1,
        D3D11_BIND_DEPTH_STENCIL);

    // Allocate a 2-D surface as the depth/stencil buffer.
    ComPtr<ID3D11Texture2D> depthStencil;
    DX::ThrowIfFailed(
        m_d3dDevice->CreateTexture2D(
            &depthStencilDesc,
            nullptr,
            &depthStencil
            )
        );

    // Create a DepthStencil view on this surface to use on bind.
    DX::ThrowIfFailed(
        m_d3dDevice->CreateDepthStencilView(
            depthStencil.Get(),
            &CD3D11_DEPTH_STENCIL_VIEW_DESC(D3D11_DSV_DIMENSION_TEXTURE2D),
            &m_depthStencilView
            )
        );

    // Create a viewport descriptor of the full window size.
    CD3D11_VIEWPORT viewPort(
        0.0f,
        0.0f,
        static_cast<float>(backBufferDesc.Width),
        static_cast<float>(backBufferDesc.Height)
        );
        
    // Set the current viewport using the descriptor.
    m_d3dContext->RSSetViewports(1, &viewPort);
}

void Direct3DBase::UpdateForWindowSizeChange()
{
    if (m_window->Bounds.Width  != m_windowBounds.Width ||
        m_window->Bounds.Height != m_windowBounds.Height)
    {
        m_renderTargetView = nullptr;
        m_depthStencilView = nullptr;
        CreateWindowSizeDependentResources();
    }
}

void Direct3DBase::Present()
{
    // The first argument instructs DXGI to block until VSync, putting the application
    // to sleep until the next VSync. This ensures we don't waste any cycles rendering
    // frames that will never be displayed to the screen.
    HRESULT hr = m_swapChain->Present(1, 0);

    // If the device was removed either by a disconnect or a driver upgrade, we 
    // must completely reinitialize the renderer.
    if (hr == DXGI_ERROR_DEVICE_REMOVED || hr == DXGI_ERROR_DEVICE_RESET)
    {
        Initialize(m_window.Get());
    }
    else
    {
        DX::ThrowIfFailed(hr);
    }
}