From e173318de20dba2dff7c5b8b64089005ff168583 Mon Sep 17 00:00:00 2001
From: baldurk <baldurk@baldurk.org>
Date: Fri, 16 Sep 2016 17:10:22 +0200
Subject: [PATCH] Don't copy buffers that are already on a readback heap, read
 directly

---
 renderdoc/driver/d3d12/d3d12_manager.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/renderdoc/driver/d3d12/d3d12_manager.cpp b/renderdoc/driver/d3d12/d3d12_manager.cpp
index aaf5bc76e..c90eb986f 100644
--- a/renderdoc/driver/d3d12/d3d12_manager.cpp
+++ b/renderdoc/driver/d3d12/d3d12_manager.cpp
@@ -470,6 +470,15 @@ bool D3D12ResourceManager::Prepare_InitialState(ID3D12DeviceChild *res)
     if(desc.Dimension == D3D12_RESOURCE_DIMENSION_BUFFER)
     {
       D3D12_HEAP_PROPERTIES heapProps;
+      r->GetHeapProperties(&heapProps, NULL);
+
+      if(heapProps.Type == D3D12_HEAP_TYPE_READBACK)
+      {
+        // already on readback heap, just mark that we can map it directly and continue
+        SetInitialContents(GetResID(r), D3D12ResourceManager::InitialContentData(NULL, 1, NULL));
+        return true;
+      }
+
       heapProps.Type = D3D12_HEAP_TYPE_READBACK;
       heapProps.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
       heapProps.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;
@@ -607,7 +616,7 @@ bool D3D12ResourceManager::Prepare_InitialState(ID3D12DeviceChild *res)
   return false;
 }
 
-bool D3D12ResourceManager::Serialise_InitialState(ResourceId resid, ID3D12DeviceChild *)
+bool D3D12ResourceManager::Serialise_InitialState(ResourceId resid, ID3D12DeviceChild *liveRes)
 {
   D3D12ResourceRecord *record = NULL;
   if(m_State >= WRITING)
@@ -634,6 +643,11 @@ bool D3D12ResourceManager::Serialise_InitialState(ResourceId resid, ID3D12Device
 
       ID3D12Resource *copiedBuffer = (ID3D12Resource *)initContents.resource;
 
+      if(initContents.num == 1)
+      {
+        copiedBuffer = (ID3D12Resource *)liveRes;
+      }
+
       byte dummy[4] = {};
       byte *ptr = NULL;
       size_t size = 0;