From 401ac2f1433825b0aaaef384ab38713462dd20ce Mon Sep 17 00:00:00 2001
From: awemancba <kelan_10@hotmail.com>
Date: Sun, 2 Aug 2026 20:08:30 -0300
Subject: [PATCH] Fix Windows Vulkan build: link dxgi for the DXGI presenter
 regardless of backend

The presenter (rexui) uses DXGI for the swapchain on Windows regardless of
the graphics backend, but dxgi was only linked in the D3D12 branch of
src/graphics/CMakeLists.txt, so a Vulkan build on Windows failed at link
time with an undefined CreateDXGIFactory1.

Also documents building with the Vulkan backend on Windows in the README
(configure command + notes about the shared SDK output dir and the
RelWithDebInfo requirement).
---
 README.md                                     | 33 +++++++++++++++++++
 tools/rexglue-sdk/src/graphics/CMakeLists.txt |  5 +++
 2 files changed, 38 insertions(+)

diff --git a/README.md b/README.md
index a5a562e6..4d7548d6 100644
--- a/README.md
+++ b/README.md
@@ -296,6 +296,39 @@ python launcher/launcher.py
 The build stages `rexruntime*.dll` and `TracyClient*.dll` next to `simpsons.exe`
 automatically — Windows has no `LD_LIBRARY_PATH`, so DLLs live beside the exe.
 
+### Building with Vulkan on Windows
+
+Windows defaults to the **D3D12** backend, but the **Vulkan** backend also builds and
+runs on Windows (it is the default on Linux). This is useful if you want the fragment
+shader interlock render path, or if you are hitting a D3D12-only issue — for example,
+FMV playback (`.vp6`) currently shows a black screen on the host render target path
+(D3D12, and Vulkan with `render_target_path_vulkan=""`), while it plays fine on the
+Vulkan interlock path.
+
+Prerequisites are the same as the D3D12 build above. Configure a separate build
+directory so the SDK output does not clobber the D3D12 one:
+
+```powershell
+cmake -S simpsons -B simpsons/out/build/win-vk -G Ninja `
+      -DCMAKE_BUILD_TYPE=RelWithDebInfo `
+      -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ `
+      "-DCMAKE_CXX_FLAGS=-march=x86-64-v3" `
+      -DREXGLUE_USE_D3D12=OFF -DREXGLUE_USE_VULKAN=ON `
+      -DREXSDK_DIR="$PWD/tools/rexglue-sdk"
+cmake --build simpsons/out/build/win-vk --target simpsons
+```
+
+Notes:
+
+- The Vulkan backend links `dxgi` on Windows because the presenter (`rexui`) uses
+  DXGI for the swapchain regardless of the graphics backend (this was only linked in
+  the D3D12 branch).
+- The SDK output directory (`tools/rexglue-sdk/out/win-amd64`) is shared between the
+  D3D12 and Vulkan builds — building the Vulkan variant overwrites
+  `rexruntimerd.dll` there, so back it up before switching back to D3D12.
+- Use a `RelWithDebInfo`/`Release` build type: without `-DNDEBUG`, the render path
+  assertions (`GetPath() == Path::kHostRenderTargets`) fire on the interlock path.
+
 ## Legal & disclaimers
 
 *The Simpsons Game* © 2007 Electronic Arts / Fox. This is an unaffiliated, non-commercial
diff --git a/tools/rexglue-sdk/src/graphics/CMakeLists.txt b/tools/rexglue-sdk/src/graphics/CMakeLists.txt
index 8e898b63..e9769aba 100644
--- a/tools/rexglue-sdk/src/graphics/CMakeLists.txt
+++ b/tools/rexglue-sdk/src/graphics/CMakeLists.txt
@@ -130,6 +130,11 @@ if(REXGLUE_USE_VULKAN)
         glslang::SPIRV
         GPUOpen::VulkanMemoryAllocator
     )
+    # The presenter (rexui) uses DXGI for the swapchain/display on Windows
+    # regardless of the graphics backend.
+    if(WIN32)
+        target_link_libraries(rexgraphics PUBLIC dxgi)
+    endif()
     target_link_libraries(rexgraphics PRIVATE
         glslang
         MachineIndependent