From 4795cf3666814ce20b42e3ede7f2e47a6a3d123c Mon Sep 17 00:00:00 2001
From: myT <>
Date: Sat, 18 Nov 2023 04:02:14 +0100
Subject: [PATCH] don't issue barriers in BeginTextureReadback when not needed

---
 code/renderer/rhi_d3d12.cpp | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/code/renderer/rhi_d3d12.cpp b/code/renderer/rhi_d3d12.cpp
index 28b6a28..9806f49 100644
--- a/code/renderer/rhi_d3d12.cpp
+++ b/code/renderer/rhi_d3d12.cpp
@@ -1162,17 +1162,27 @@ namespace RHI
 		srcBox.bottom = textureDesc.Height;
 		srcBox.back = 1;
 
+		const D3D12_RESOURCE_STATES prevState = texture.currentState;
+
 		// @TODO: use CmdBarrier
 		D3D12_RESOURCE_BARRIER barrier = {};
 		barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
 		barrier.Transition.pResource = texture.texture;
-		barrier.Transition.StateBefore = texture.currentState;
+		barrier.Transition.StateBefore = prevState;
 		barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_COPY_SOURCE;
-		readbackCommandList->ResourceBarrier(1, &barrier);
+		if(texture.currentState != D3D12_RESOURCE_STATE_COPY_SOURCE)
+		{
+			readbackCommandList->ResourceBarrier(1, &barrier);
+			texture.currentState = D3D12_RESOURCE_STATE_COPY_SOURCE;
+		}
 		readbackCommandList->CopyTextureRegion(&dstLoc, 0, 0, 0, &srcLoc, &srcBox);
 		barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_COPY_SOURCE;
-		barrier.Transition.StateAfter = texture.currentState;
-		readbackCommandList->ResourceBarrier(1, &barrier);
+		barrier.Transition.StateAfter = prevState;
+		if(texture.currentState != prevState)
+		{
+			readbackCommandList->ResourceBarrier(1, &barrier);
+			texture.currentState = prevState;
+		}
 
 		D3D(readbackCommandList->Close());
 		ID3D12CommandList* commandListArray[] = { readbackCommandList };