From ec8bf73b9f2cd5be71b664ae54c4c9f38fc9d564 Mon Sep 17 00:00:00 2001
From: cdozdil <cdozdil@gmail.com>
Date: Tue, 12 Aug 2025 23:07:02 +0300
Subject: [PATCH] Added PoC V-Sync control

---
 OptiScaler/State.h              |  2 ++
 OptiScaler/hooks/HooksDx.cpp    | 24 ++++++++++++++++
 OptiScaler/menu/menu_common.cpp | 51 +++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+)

diff --git a/OptiScaler/State.h b/OptiScaler/State.h
index 082871ad..b80a4627 100644
--- a/OptiScaler/State.h
+++ b/OptiScaler/State.h
@@ -95,6 +95,8 @@ class State
     bool FGchanged = false;
     bool SCchanged = false;
     bool skipHeapCapture = false;
+    std::optional<bool> forceVsync;
+    UINT vsyncInterval = 0;
 
     bool FGcaptureResources = false;
     int FGcapturedResourceCount = false;
diff --git a/OptiScaler/hooks/HooksDx.cpp b/OptiScaler/hooks/HooksDx.cpp
index ba9adfce..ee6c25c0 100644
--- a/OptiScaler/hooks/HooksDx.cpp
+++ b/OptiScaler/hooks/HooksDx.cpp
@@ -297,6 +297,21 @@ static HRESULT hkFGPresent(void* This, UINT SyncInterval, UINT Flags)
             LOG_WARN("Couldn't copy hudless into the backbuffer");
     }
 
+    if (willPresent && State::Instance().forceVsync.has_value())
+    {
+        if (!State::Instance().forceVsync.value())
+        {
+            SyncInterval = 0;
+            Flags |= DXGI_PRESENT_ALLOW_TEARING;
+        }
+        else
+        {
+            // Remove allow tearing
+            SyncInterval = State::Instance().vsyncInterval;
+            Flags &= 0xFDFF;
+        }
+    }
+
     HRESULT result;
     result = o_FGSCPresent(This, SyncInterval, Flags);
     LOG_DEBUG("Result: {:X}", result);
@@ -681,6 +696,9 @@ static HRESULT hkCreateSwapChainForCoreWindow(IDXGIFactory2* pFactory, IUnknown*
         pDesc->Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
     }
 
+    // For vsync override
+    pDesc->Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
+
     ID3D12CommandQueue* realQ = nullptr;
     if (!CheckForRealObject(__FUNCTION__, pDevice, (IUnknown**) &realQ))
         realQ = (ID3D12CommandQueue*) pDevice;
@@ -821,6 +839,9 @@ static HRESULT hkCreateSwapChain(IDXGIFactory* pFactory, IUnknown* pDevice, DXGI
               pDesc->BufferDesc.Width, pDesc->BufferDesc.Height, (UINT) pDesc->BufferDesc.Format, pDesc->BufferCount,
               (UINT) pDesc->OutputWindow, pDesc->Windowed, _skipFGSwapChainCreation);
 
+    // For vsync override
+    pDesc->Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
+
     // Crude implementation of EndlesslyFlowering's AutoHDR-ReShade
     // https://github.com/EndlesslyFlowering/AutoHDR-ReShade
     if (Config::Instance()->ForceHDR.value_or_default() && !_skipFGSwapChainCreation)
@@ -1147,6 +1168,9 @@ static HRESULT hkCreateSwapChainForHwnd(IDXGIFactory* This, IUnknown* pDevice, H
         pDesc->Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
     }
 
+    // For vsync override
+    pDesc->Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
+
     // Disable FSR FG if amd dll is not found
     if (State::Instance().activeFgOutput == FGOutput::FSRFG && !FfxApiProxy::InitFfxDx12())
     {
diff --git a/OptiScaler/menu/menu_common.cpp b/OptiScaler/menu/menu_common.cpp
index 345ae766..6ae79ed4 100644
--- a/OptiScaler/menu/menu_common.cpp
+++ b/OptiScaler/menu/menu_common.cpp
@@ -2634,6 +2634,57 @@ bool MenuCommon::RenderMenu()
                                    "UI elements and ONLY UI elements should have a pink tint!");
                 }
 
+                auto forceVsyncOn = State::Instance().forceVsync.has_value() && State::Instance().forceVsync.value();
+                auto forceVsyncOff = State::Instance().forceVsync.has_value() && !State::Instance().forceVsync.value();
+
+                if (ImGui::Checkbox("Force: V-Sync On", &forceVsyncOn))
+                {
+                    if (forceVsyncOn)
+                        State::Instance().forceVsync = true;
+                    else
+                        State::Instance().forceVsync.reset();
+                }
+
+                ImGui::SameLine(0.0f, 16.0f);
+
+                if (ImGui::Checkbox("V-Sync Off", &forceVsyncOff))
+                {
+                    if (forceVsyncOff)
+                        State::Instance().forceVsync = false;
+                    else
+                        State::Instance().forceVsync.reset();
+                }
+
+                ImGui::SameLine(0.0f, 16.0f);
+
+                ImGui::BeginDisabled(forceVsyncOff);
+
+                ImGui::PushItemWidth(50.0f * Config::Instance()->MenuScale.value_or_default());
+                if (ImGui::BeginCombo("Sync Int.", std::format("{}", State::Instance().vsyncInterval).c_str()))
+                {
+                    if (ImGui::Selectable("0", State::Instance().vsyncInterval == 0))
+                        State::Instance().vsyncInterval = 0;
+
+                    if (ImGui::Selectable("1", State::Instance().vsyncInterval == 1))
+                        State::Instance().vsyncInterval = 1;
+
+                    if (ImGui::Selectable("2", State::Instance().vsyncInterval == 2))
+                        State::Instance().vsyncInterval = 2;
+
+                    if (ImGui::Selectable("3", State::Instance().vsyncInterval == 3))
+                        State::Instance().vsyncInterval = 3;
+
+                    ImGui::EndCombo();
+                }
+                ImGui::PopItemWidth();
+
+                ImGui::EndDisabled();
+
+                ImGui::SameLine(0.0f, 16.0f);
+
+                if (ImGui::Button("Reset##10"))
+                    State::Instance().forceVsync.reset();
+
                 // if (State::Instance().activeFgInput != Config::Instance()->FGInput.value_or_default())
                 //{
                 //     State::Instance().activeFgInput = Config::Instance()->FGInput.value_or_default();