初始化过程
初始化DirectX 3D的过程可以分为9步。
1.创建ID3D12Device
2.创建ID3D12Fence并查找descriptor的大小
3.查询4X MSAA支持的的quality level
4.创建一个command queue、command list allocator和主要的command list
5.创建swap chain
6.创建描述符堆
7.指定back buffer的大小然后创建rtv指向back buffer
8.创建depth/stencil buffer和对应的dsv
9.设置viewport和裁剪区域
创建ID3D12Device
ThrowIfFailed(CreateDXGIFactory1(IID_PPV_ARGS(&mdxgiFactory)));
// Try to create hardware device.
HRESULT hardwareResult = D3D12CreateDevice(
nullptr, // default adapter
D3D_FEATURE_LEVEL_11_0,
IID_PPV_ARGS(&md3dDevice));
// Fallback to WARP device.
if(FAILED(hardwareResult))
{
ComPtr<IDXGIAdapter> pWarpAdapter;
ThrowIfFailed(mdxgiFactory->EnumWarpAdapter(IID_PPV_ARGS(&pWarpAdapter)));
ThrowIfFailed(D3D12CreateDevice(
pWarpAdapter.Get(),
D3D_FEATURE_LEVEL_11_0,
IID_PPV_ARGS(&md3dDevice)));
}
创建Fence和查询描述符大小
ThrowIfFailed(md3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE,
IID_PPV_ARGS(&mFence)));
mRtvDescriptorSize = md3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
mDsvDescriptorSize = md3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_DSV);
mCbvSrvUavDescriptorSize = md3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);
查询4X MSAA支持的Quality Level
// Check 4X MSAA quality support for our back buffer format.
// All Direct3D 11 capable devices support 4X MSAA for all render
// target formats, so we only need to check quality support.
D3D12_FEATURE_DATA_MULTISAMPLE_QUALITY_LEVELS msQualityLevels;
msQualityLevels.Format = mBackBufferFormat;
msQualityLevels.SampleCount = 4;
msQualityLevels.Flags = D3D12_MULTISAMPLE_QUALITY_LEVELS_FLAG_NONE;
msQualityLevels.NumQualityLevels = 0;
ThrowIfFailed(md3dDevice->CheckFeatureSupport(
D3D12_FEATURE_MULTISAMPLE_QUALITY_LEVELS,
&msQualityLevels,
sizeof(msQualityLevels)));
m4xMsaaQuality = msQualityLevels.NumQualityLevels;
assert(m4xMsaaQuality > 0 && "Unexpected MSAA quality level.");
创建Command Objects
D3D12_COMMAND_QUEUE_DESC queueDesc = {};
queueDesc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
queueDesc.Flags = D3D12_COMMAND_QUEUE_FLAG_NONE;
ThrowIfFailed(md3dDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&mCommandQueue)));
ThrowIfFailed(md3dDevice->CreateCommandAllocator(
D3D12_COMMAND_LIST_TYPE_DIRECT,
IID_PPV_ARGS(mDirectCmdListAlloc.GetAddressOf())));
ThrowIfFailed(md3dDevice->CreateCommandList(
0,
D3D12_COMMAND_LIST_TYPE_DIRECT,
mDirectCmdListAlloc.Get(), // Associated command allocator
nullptr, // Initial PipelineStateObject
IID_PPV_ARGS(mCommandList.GetAddressOf())));
// Start off in a closed state. This is because the first time we refer
// to the command list we will Reset it, and it needs to be closed before
// calling Reset.
mCommandList->Close();
创建Swap Chain
创建swapchain的时候会创建SwapChainBufferCount个缓冲区，所以不需要我们再创建几个render target的resource，后面只要直接创建view就行了。
创建view的时候，需要的recource用SwapChain->GetBuffer方法取得。
// Release the previous swapchain we will be recreating.
mSwapChain.Reset();
DXGI_SWAP_CHAIN_DESC sd;
sd.BufferDesc.Width = mClientWidth;
sd.BufferDesc.Height = mClientHeight;
sd.BufferDesc.RefreshRate.Numerator = 60;
sd.BufferDesc.RefreshRate.Denominator = 1;
sd.BufferDesc.Format = mBackBufferFormat;
sd.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
sd.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;
sd.SampleDesc.Count = m4xMsaaState ? 4 : 1;
sd.SampleDesc.Quality = m4xMsaaState ? (m4xMsaaQuality - 1) : 0;
sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
sd.BufferCount = SwapChainBufferCount;
sd.OutputWindow = mhMainWnd;
sd.Windowed = true;
sd.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
sd.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;
// Note: Swap chain uses queue to perform flush.
ThrowIfFailed(mdxgiFactory->CreateSwapChain(
mCommandQueue.Get(),
&sd,
mSwapChain.GetAddressOf()));
创建dsv堆和rtv堆
D3D12_DESCRIPTOR_HEAP_DESC rtvHeapDesc;
rtvHeapDesc.NumDescriptors = SwapChainBufferCount;
rtvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
rtvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
rtvHeapDesc.NodeMask = 0;
ThrowIfFailed(md3dDevice->CreateDescriptorHeap(
&rtvHeapDesc, IID_PPV_ARGS(mRtvHeap.GetAddressOf())));
D3D12_DESCRIPTOR_HEAP_DESC dsvHeapDesc;
dsvHeapDesc.NumDescriptors = 1;
dsvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_DSV;
dsvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
dsvHeapDesc.NodeMask = 0;
ThrowIfFailed(md3dDevice->CreateDescriptorHeap(
&dsvHeapDesc, IID_PPV_ARGS(mDsvHeap.GetAddressOf())));
创建多个rtv和一个dsv
书上的示例程序把这一步和下一步写在了OnResize()里了，并且在Initialize的最后一步调用了OnResize()。
assert(md3dDevice);
assert(mSwapChain);
assert(mDirectCmdListAlloc);
// Flush before changing any resources.
FlushCommandQueue();
ThrowIfFailed(mCommandList->Reset(mDirectCmdListAlloc.Get(), nullptr));
// Release the previous resources we will be recreating.
for (int i = 0; i < SwapChainBufferCount; ++i)
mSwapChainBuffer[i].Reset();
mDepthStencilBuffer.Reset();
// Resize the swap chain.
ThrowIfFailed(mSwapChain->ResizeBuffers(
SwapChainBufferCount,
mClientWidth, mClientHeight,
mBackBufferFormat,
DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH));
mCurrBackBuffer = 0;
CD3DX12_CPU_DESCRIPTOR_HANDLE rtvHeapHandle(mRtvHeap->GetCPUDescriptorHandleForHeapStart());
for (UINT i = 0; i < SwapChainBufferCount; i++)
{
ThrowIfFailed(mSwapChain->GetBuffer(i, IID_PPV_ARGS(&mSwapChainBuffer[i])));
md3dDevice->CreateRenderTargetView(mSwapChainBuffer[i].Get(), nullptr, rtvHeapHandle);
rtvHeapHandle.Offset(1, mRtvDescriptorSize);
}
// Create the depth/stencil buffer and view.
D3D12_RESOURCE_DESC depthStencilDesc;
depthStencilDesc.Dimension = D3D12_RESOURCE_DIMENSION_TEXTURE2D;
depthStencilDesc.Alignment = 0;
depthStencilDesc.Width = mClientWidth;
depthStencilDesc.Height = mClientHeight;
depthStencilDesc.DepthOrArraySize = 1;
depthStencilDesc.MipLevels = 1;
depthStencilDesc.Format = mDepthStencilFormat;
depthStencilDesc.SampleDesc.Count = m4xMsaaState ? 4 : 1;
depthStencilDesc.SampleDesc.Quality = m4xMsaaState ? (m4xMsaaQuality - 1) : 0;
depthStencilDesc.Layout = D3D12_TEXTURE_LAYOUT_UNKNOWN;
depthStencilDesc.Flags = D3D12_RESOURCE_FLAG_ALLOW_DEPTH_STENCIL;
D3D12_CLEAR_VALUE optClear;
optClear.Format = mDepthStencilFormat;
optClear.DepthStencil.Depth = 1.0f;
optClear.DepthStencil.Stencil = 0;
ThrowIfFailed(md3dDevice->CreateCommittedResource(
&CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
D3D12_HEAP_FLAG_NONE,
&depthStencilDesc,
D3D12_RESOURCE_STATE_COMMON,
&optClear,
IID_PPV_ARGS(mDepthStencilBuffer.GetAddressOf())));
// Create descriptor to mip level 0 of entire resource using the format of the resource.
md3dDevice->CreateDepthStencilView(mDepthStencilBuffer.Get(), nullptr, DepthStencilView());
// Transition the resource from its initial state to be used as a depth buffer.
mCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(mDepthStencilBuffer.Get(),
D3D12_RESOURCE_STATE_COMMON, D3D12_RESOURCE_STATE_DEPTH_WRITE));
// Execute the resize commands.
ThrowIfFailed(mCommandList->Close());
ID3D12CommandList* cmdsLists[] = { mCommandList.Get() };
mCommandQueue->ExecuteCommandLists(_countof(cmdsLists), cmdsLists);
设置Viewport和ScissorRect
// Wait until resize is complete.
FlushCommandQueue();
// Update the viewport transform to cover the client area.
mScreenViewport.TopLeftX = 0;
mScreenViewport.TopLeftY = 0;
mScreenViewport.Width = static_cast<float>(mClientWidth);
mScreenViewport.Height = static_cast<float>(mClientHeight);
mScreenViewport.MinDepth = 0.0f;
mScreenViewport.MaxDepth = 1.0f;
mScissorRect = { 0, 0, mClientWidth, mClientHeight };
初始化demo
书上还写了一个简单的初始化demo，可以创建一个窗口并输出一个纯色。该demo应用继承自书本自己封装的D3DApp然后重载了Draw函数。
void InitDirect3DApp::Draw(const GameTimer& gt)
{
// Reuse the memory associated with command recording.
// We can only reset when the associated command lists have finished execution on the GPU.
ThrowIfFailed(mDirectCmdListAlloc->Reset());
// A command list can be reset after it has been added to the command queue via ExecuteCommandList.
// Reusing the command list reuses memory.
ThrowIfFailed(mCommandList->Reset(mDirectCmdListAlloc.Get(), nullptr));
// Indicate a state transition on the resource usage.
mCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(CurrentBackBuffer(),
D3D12_RESOURCE_STATE_PRESENT, D3D12_RESOURCE_STATE_RENDER_TARGET));
// Set the viewport and scissor rect. This needs to be reset whenever the command list is reset.
mCommandList->RSSetViewports(1, &mScreenViewport);
mCommandList->RSSetScissorRects(1, &mScissorRect);
// Clear the back buffer and depth buffer.
mCommandList->ClearRenderTargetView(CurrentBackBufferView(), Colors::LightSteelBlue, 0, nullptr);
mCommandList->ClearDepthStencilView(DepthStencilView(), D3D12_CLEAR_FLAG_DEPTH | D3D12_CLEAR_FLAG_STENCIL, 1.0f, 0, 0, nullptr);
// Specify the buffers we are going to render to.
mCommandList->OMSetRenderTargets(1, &CurrentBackBufferView(), true, &DepthStencilView());
// Indicate a state transition on the resource usage.
mCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(CurrentBackBuffer(),
D3D12_RESOURCE_STATE_RENDER_TARGET, D3D12_RESOURCE_STATE_PRESENT));
// Done recording commands.
ThrowIfFailed(mCommandList->Close());
// Add the command list to the queue for execution.
ID3D12CommandList* cmdsLists[] = { mCommandList.Get() };
mCommandQueue->ExecuteCommandLists(_countof(cmdsLists), cmdsLists);
// swap the back and front buffers
ThrowIfFailed(mSwapChain->Present(0, 0));
mCurrBackBuffer = (mCurrBackBuffer + 1) % SwapChainBufferCount;
// Wait until frame commands are complete. This waiting is inefficient and is
// done for simplicity. Later we will show how to organize our rendering code
// so we do not have to wait per frame.
FlushCommandQueue();
}
运行结果
编译运行代码可以得到以下结果
![[DirectX12学习笔记] 初始化之美_ DirectX](http://dev-img.mos.moduyun.com/20231027/761c1b7f-3163-415b-ac26-9c27d36b2791.png)