From 0a5b427ded6e4de61e7eded4473fccd4d63cb356 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Sun, 13 Oct 2019 02:00:10 +0200
Subject: [PATCH] [dxvk] Add function to insert framebuffer read-back barriers

Required for some D3D9 content.
---
 src/dxvk/dxvk_context.cpp    | 11 +++++++++++
 src/dxvk/dxvk_context.h      |  8 ++++++++
 src/dxvk/dxvk_renderpass.cpp | 12 ++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/src/dxvk/dxvk_context.cpp b/src/dxvk/dxvk_context.cpp
index 253a8bc4..8039f77b 100644
--- a/src/dxvk/dxvk_context.cpp
+++ b/src/dxvk/dxvk_context.cpp
@@ -1586,6 +1586,17 @@ namespace dxvk {
   }
 
 
+  void DxvkContext::emitRenderTargetReadbackBarrier() {
+    if (m_flags.test(DxvkContextFlag::GpRenderPassBound)) {
+      emitMemoryBarrier(VK_DEPENDENCY_BY_REGION_BIT,
+        VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
+        VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
+        VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
+        VK_ACCESS_SHADER_READ_BIT);
+    }
+  }
+
+
   void DxvkContext::initImage(
     const Rc<DxvkImage>&           image,
     const VkImageSubresourceRange& subresources,
diff --git a/src/dxvk/dxvk_context.h b/src/dxvk/dxvk_context.h
index a26c4e5c..8e6c246e 100644
--- a/src/dxvk/dxvk_context.h
+++ b/src/dxvk/dxvk_context.h
@@ -608,6 +608,14 @@ namespace dxvk {
             uint32_t          counterDivisor,
             uint32_t          counterBias);
     
+    /**
+     * \brief Emits barrier for render target readback
+     *
+     * Use between draw calls if the fragment shader
+     * reads one of the currently bound render targets.
+     */
+    void emitRenderTargetReadbackBarrier();
+
     /**
      * \brief Generates mip maps
      * 
diff --git a/src/dxvk/dxvk_renderpass.cpp b/src/dxvk/dxvk_renderpass.cpp
index 8c5f5a55..fd4baa43 100644
--- a/src/dxvk/dxvk_renderpass.cpp
+++ b/src/dxvk/dxvk_renderpass.cpp
@@ -151,6 +151,18 @@ namespace dxvk {
         VK_ACCESS_TRANSFORM_FEEDBACK_COUNTER_READ_BIT_EXT, 0 };
     }
 
+    if (ops.barrier.srcStages & (
+          VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT |
+          VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT |
+          VK_PIPELINE_STAGE_ALL_COMMANDS_BIT)) {
+      subpassDeps[subpassDepCount++] = { 0, 0,
+        VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT,
+        VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
+        VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT,
+        VK_ACCESS_SHADER_READ_BIT,
+        VK_DEPENDENCY_BY_REGION_BIT };
+    }
+
     if (ops.barrier.srcStages && ops.barrier.dstStages) {
       subpassDeps[subpassDepCount++] = {
         0, VK_SUBPASS_EXTERNAL,