From f55a5ff022cffd85c497e29a32bb4603b4897e01 Mon Sep 17 00:00:00 2001
From: assiduous <assiduous@diligentgraphics.com>
Date: Thu, 2 Jan 2020 22:55:54 -0800
Subject: A bunch of minor updated to D3D12 queries

---
 Graphics/GraphicsEngineD3D12/include/QueryManager.h | 3 +++
 Graphics/GraphicsEngineD3D12/src/QueryD3D12Impl.cpp | 5 ++++-
 Graphics/GraphicsEngineD3D12/src/QueryManager.cpp   | 7 +++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

(limited to 'Graphics/GraphicsEngineD3D12')

diff --git a/Graphics/GraphicsEngineD3D12/include/QueryManager.h b/Graphics/GraphicsEngineD3D12/include/QueryManager.h
index a3e37645..fc8044f9 100644
--- a/Graphics/GraphicsEngineD3D12/include/QueryManager.h
+++ b/Graphics/GraphicsEngineD3D12/include/QueryManager.h
@@ -39,6 +39,8 @@ namespace Diligent
 
 class CommandContext;
 
+// https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#queries
+
 class QueryManager
 {
 public:
@@ -79,6 +81,7 @@ private:
     std::mutex                                      m_HeapMutex;
     std::array<QueryHeapInfo, QUERY_TYPE_NUM_TYPES> m_Heaps;
 
+    // Readback buffer that will contain the query data.
     CComPtr<ID3D12Resource> m_pd3d12ResolveBuffer;
 };
 
diff --git a/Graphics/GraphicsEngineD3D12/src/QueryD3D12Impl.cpp b/Graphics/GraphicsEngineD3D12/src/QueryD3D12Impl.cpp
index 073f839a..1e102bd5 100644
--- a/Graphics/GraphicsEngineD3D12/src/QueryD3D12Impl.cpp
+++ b/Graphics/GraphicsEngineD3D12/src/QueryD3D12Impl.cpp
@@ -90,7 +90,9 @@ bool QueryD3D12Impl::GetData(void* pData, Uint32 DataSize)
             {
                 UINT64 AnySamplePassed;
                 QueryMgr.ReadQueryData(m_Desc.Type, m_QueryHeapIndex, &AnySamplePassed, sizeof(AnySamplePassed));
-                auto& QueryData           = *reinterpret_cast<QueryDataBinaryOcclusion*>(pData);
+                auto& QueryData = *reinterpret_cast<QueryDataBinaryOcclusion*>(pData);
+                // Binary occlusion queries write 64-bits per query. The least significant bit is either 0 or 1. The rest of the bits are 0.
+                // https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#resolvequerydata
                 QueryData.AnySamplePassed = AnySamplePassed != 0;
             }
             break;
@@ -105,6 +107,7 @@ bool QueryD3D12Impl::GetData(void* pData, Uint32 DataSize)
                 const auto& CmdQueue    = m_pDevice->GetCommandQueue(CmdQueueId);
                 auto*       pd3d12Queue = const_cast<ICommandQueueD3D12&>(CmdQueue).GetD3D12CommandQueue();
 
+                // https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#timestamp-frequency
                 UINT64 TimestampFrequency = 0;
                 pd3d12Queue->GetTimestampFrequency(&TimestampFrequency);
                 QueryData.Frequency = TimestampFrequency;
diff --git a/Graphics/GraphicsEngineD3D12/src/QueryManager.cpp b/Graphics/GraphicsEngineD3D12/src/QueryManager.cpp
index 00a37076..6474383c 100644
--- a/Graphics/GraphicsEngineD3D12/src/QueryManager.cpp
+++ b/Graphics/GraphicsEngineD3D12/src/QueryManager.cpp
@@ -80,6 +80,8 @@ QueryManager::QueryManager(ID3D12Device* pd3d12Device,
         auto hr = pd3d12Device->CreateQueryHeap(&d3d12HeapDesc, __uuidof(HeapInfo.pd3d12QueryHeap), reinterpret_cast<void**>(&HeapInfo.pd3d12QueryHeap));
         CHECK_D3D_RESULT_THROW(hr, "Failed to create D3D12 query heap of type");
 
+        // AlignedDestinationBufferOffset must be a multiple of 8 bytes.
+        // https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#resolvequerydata
         Uint32 AlignedQueryDataSize = Align(GetQueryDataSize(static_cast<QUERY_TYPE>(QueryType)), Uint32{8});
         HeapInfo.AvailableQueries.resize(HeapInfo.HeapSize);
         HeapInfo.ResolveBufferOffsets.resize(HeapInfo.HeapSize);
@@ -113,6 +115,9 @@ QueryManager::QueryManager(ID3D12Device* pd3d12Device,
     HeapProps.CreationNodeMask      = 1;
     HeapProps.VisibleNodeMask       = 1;
 
+    // The destination buffer of a query resolve operation must be in the D3D12_RESOURCE_USAGE_COPY_DEST state.
+    // ResolveQueryData works with all heap types (default, upload, readback).
+    // https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#resolvequerydata
     auto hr = pd3d12Device->CreateCommittedResource(&HeapProps, D3D12_HEAP_FLAG_NONE,
                                                     &D3D12BuffDesc, D3D12_RESOURCE_STATE_COPY_DEST, nullptr,
                                                     __uuidof(m_pd3d12ResolveBuffer),
@@ -185,6 +190,8 @@ void QueryManager::EndQuery(CommandContext& Ctx, QUERY_TYPE Type, Uint32 Index)
     auto  d3d12QueryType = QueryTypeToD3D12QueryType(Type);
     auto& HeapInfo       = m_Heaps[Type];
     Ctx.EndQuery(HeapInfo.pd3d12QueryHeap, d3d12QueryType, Index);
+
+    // https://microsoft.github.io/DirectX-Specs/d3d/CountersAndQueries.html#resolvequerydata
     Ctx.ResolveQueryData(HeapInfo.pd3d12QueryHeap, d3d12QueryType, Index, 1, m_pd3d12ResolveBuffer, HeapInfo.ResolveBufferOffsets[Index]);
 }
 
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