From 7583db3bef522e0303ec913e6d5f0011e347d88d Mon Sep 17 00:00:00 2001
From: Flyinghead <raphael.jean@gmail.com>
Date: Wed, 10 Nov 2021 20:55:22 +0100
Subject: [PATCH] vk: option to duplicate frames to simulate swap interval > 1

Issue #293
---
 core/cfg/option.cpp                 |  1 +
 core/cfg/option.h                   |  1 +
 core/rend/gui.cpp                   | 13 +++++++++++++
 core/rend/vulkan/vulkan_context.cpp |  5 +----
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/core/cfg/option.cpp b/core/cfg/option.cpp
index 114f83cce..9ea1e8bc2 100644
--- a/core/cfg/option.cpp
+++ b/core/cfg/option.cpp
@@ -96,6 +96,7 @@ Option<bool> VSync("rend.vsync", true);
 Option<u64> PixelBufferSize("rend.PixelBufferSize", 512 * 1024 * 1024);
 Option<int> AnisotropicFiltering("rend.AnisotropicFiltering", 1);
 Option<bool> ThreadedRendering("rend.ThreadedRendering", true);
+Option<bool> DupeFrames("rend.DupeFrames", false);
 
 // Misc
 
diff --git a/core/cfg/option.h b/core/cfg/option.h
index 65b1a0f86..e4cac2b6b 100644
--- a/core/cfg/option.h
+++ b/core/cfg/option.h
@@ -436,6 +436,7 @@ extern Option<bool> VSync;
 extern Option<u64> PixelBufferSize;
 extern Option<int> AnisotropicFiltering;
 extern Option<bool> ThreadedRendering;
+extern Option<bool> DupeFrames;
 
 // Misc
 
diff --git a/core/rend/gui.cpp b/core/rend/gui.cpp
index 73578e648..66bbf8f69 100644
--- a/core/rend/gui.cpp
+++ b/core/rend/gui.cpp
@@ -1616,6 +1616,19 @@ static void gui_display_settings()
 #ifndef TARGET_IPHONE
 		    	OptionCheckbox("VSync", config::VSync, "Synchronizes the frame rate with the screen refresh rate. Recommended");
 #endif
+		    	ImGui::Indent();
+		    	if (!config::VSync || !isVulkan(config::RendererType))
+		    	{
+			        ImGui::PushItemFlag(ImGuiItemFlags_Disabled, true);
+			        ImGui::PushStyleVar(ImGuiStyleVar_Alpha, ImGui::GetStyle().Alpha * 0.5f);
+		    	}
+	    		OptionCheckbox("Duplicate frames", config::DupeFrames, "Duplicate frames on high refresh rate monitors (120 Hz and higher)");
+		    	if (!config::VSync || !isVulkan(config::RendererType))
+		    	{
+			        ImGui::PopItemFlag();
+			        ImGui::PopStyleVar();
+		    	}
+		    	ImGui::Unindent();
 		    	OptionCheckbox("Show FPS Counter", config::ShowFPS, "Show on-screen frame/sec counter");
 		    	OptionCheckbox("Show VMU In-game", config::FloatVMUs, "Show the VMU LCD screens while in-game");
 		    	OptionCheckbox("Rotate Screen 90°", config::Rotate90, "Rotate the screen 90° counterclockwise");
diff --git a/core/rend/vulkan/vulkan_context.cpp b/core/rend/vulkan/vulkan_context.cpp
index 6dbaff1e4..2fd078aa4 100644
--- a/core/rend/vulkan/vulkan_context.cpp
+++ b/core/rend/vulkan/vulkan_context.cpp
@@ -567,12 +567,9 @@ void VulkanContext::CreateSwapChain()
 					break;
 				}
 			}
-			/*
-			if (swapOnVSync && settings.display.refreshRate > 60.f)
-				// TODO config option to enable duped frames
+			if (swapOnVSync && config::DupeFrames && settings.display.refreshRate > 60.f)
 				swapInterval = settings.display.refreshRate / 60.f;
 			else
-			*/
 				swapInterval = 1;
 
 			vk::SurfaceTransformFlagBitsKHR preTransform = (surfaceCapabilities.supportedTransforms & vk::SurfaceTransformFlagBitsKHR::eIdentity) ? vk::SurfaceTransformFlagBitsKHR::eIdentity : surfaceCapabilities.currentTransform;