我设置了一个仅清除后台缓冲的DX12应用程序。
它真的非常简单:没有PSO,没有根...唯一的特点是它在开始新帧之前等待SwapChain完成Present() (msdn waitable swap chain) (我将帧延迟设置为1,并且仅有2个缓冲区)。
第一帧运行正常,但它立即开始绘制第二帧,当然,命令分配器会抱怨正在执行GPU上的命令时被重置。
我当然可以设置一个fence来等待GPU完成后再移动到新的帧,但我认为这是waitable swap chain对象的工作。
以下是渲染例程:
if (m_command_allocator->Reset() == E_FAIL) { throw; }
HRESULT res = S_OK;
res = m_command_list->Reset(m_command_allocator.Get(), nullptr);
if (res == E_FAIL || res == E_OUTOFMEMORY) { throw; }
m_command_list->ResourceBarrier(1,
&CD3DX12_RESOURCE_BARRIER::Transition(m_render_targets[m_frame_index].Get(),
D3D12_RESOURCE_STATE_PRESENT, D3D12_RESOURCE_STATE_RENDER_TARGET));
m_command_list->RSSetViewports(1, &m_screen_viewport);
m_command_list->RSSetScissorRects(1, &m_scissor_rect);
m_command_list->ClearRenderTargetView(get_rtv_handle(),
DirectX::Colors::BlueViolet, 0, nullptr);
m_command_list->OMSetRenderTargets(1, &get_rtv_handle(), true, nullptr);
m_command_list->ResourceBarrier(1,
&CD3DX12_RESOURCE_BARRIER::Transition(m_render_targets[m_frame_index].Get(),
D3D12_RESOURCE_STATE_RENDER_TARGET, D3D12_RESOURCE_STATE_PRESENT));
tools::throw_if_failed(m_command_list->Close());
ID3D12CommandList* ppCommandLists[] = { m_command_list.Get() };
m_command_queue->ExecuteCommandLists(_countof(ppCommandLists),
ppCommandLists);
if (m_swap_chain->Present(1, 0) != S_OK) { throw; }
m_frame_index = m_swap_chain->GetCurrentBackBufferIndex();
我使用从交换链获取的可等待对象循环运行此例程:
while (WAIT_OBJECT_0 == WaitForSingleObjectEx(waitable_renderer, INFINITE, TRUE) && m_alive == true)
{
m_graphics.render();
}
我对交换链进行了初始化,并使用了可等待标志:
DXGI_SWAP_CHAIN_DESC1 swap_chain_desc = {};
swap_chain_desc.BufferCount = s_frame_count;
swap_chain_desc.Width = window_width;
swap_chain_desc.Height = window_height;
swap_chain_desc.Format = m_back_buffer_format;
swap_chain_desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
swap_chain_desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
swap_chain_desc.SampleDesc.Count = 1;
swap_chain_desc.Flags = DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
ComPtr<IDXGISwapChain1> swap_chain;
tools::throw_if_failed(
factory->CreateSwapChainForHwnd(m_command_queue.Get(), window_handle, &swap_chain_desc, nullptr, nullptr, &swap_chain));
在创建交换链后,我立即调用SetFrameLatency:
ComPtr<IDXGISwapChain2> swap_chain2;
tools::throw_if_failed(m_swap_chain.As(&swap_chain2));
tools::throw_if_failed(swap_chain2->SetMaximumFrameLatency(1));
m_waitable_renderer = swap_chain2->GetFrameLatencyWaitableObject();
还有与此相关的交换链调整:
tools::throw_if_failed(
m_swap_chain->ResizeBuffers(s_frame_count, window_width, window_height, m_back_buffer_format, DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT));
我的问题是:我是否设置了一些不正确的东西?或者这就是可等待交换链的工作方式(即在等待交换链可用之前,您还需要使用围栏与GPU进行同步)?
编辑:添加SetFrameLatency调用+ C ++着色。
GetFrameLatencyWaitableObject
来获取waitable_renderer
。 - user7860670