From 98d04702ae81e18c9636c1f934f883a8ebb7f1a3 Mon Sep 17 00:00:00 2001
From: Flyinghead <raphael.jean@gmail.com>
Date: Mon, 23 Aug 2021 10:10:13 +0200
Subject: [PATCH] sdl: set vsync swap interval to 2 for 120 Hz displays

Issue #293
---
 core/wsi/sdl.cpp | 18 ++++++++++++++++--
 core/wsi/sdl.h   |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/core/wsi/sdl.cpp b/core/wsi/sdl.cpp
index a07a86b16..9fa3abfea 100644
--- a/core/wsi/sdl.cpp
+++ b/core/wsi/sdl.cpp
@@ -85,7 +85,21 @@ bool SDLGLGraphicsContext::Init()
 	// Swap immediately
 	swapOnVSync = false;
 #endif
-	SDL_GL_SetSwapInterval((int)swapOnVSync);
+	swapInterval = 1;
+	int displayIndex = SDL_GetWindowDisplayIndex(window);
+	if (displayIndex < 0)
+		WARN_LOG(RENDERER, "Cannot get the window display index: %s", SDL_GetError());
+	else
+	{
+		SDL_DisplayMode mode{};
+		if (SDL_GetDesktopDisplayMode(displayIndex, &mode) == 0) {
+			INFO_LOG(RENDERER, "Monitor refresh rate: %d Hz", mode.refresh_rate);
+			if (mode.refresh_rate > 100)
+				swapInterval = 2;
+		}
+	}
+
+	SDL_GL_SetSwapInterval(swapOnVSync ? swapInterval : 0);
 
 #ifdef GLES
 	load_gles_symbols();
@@ -109,7 +123,7 @@ void SDLGLGraphicsContext::Swap()
 	if (swapOnVSync == (settings.input.fastForwardMode || !config::VSync))
 	{
 		swapOnVSync = (!settings.input.fastForwardMode && config::VSync);
-		SDL_GL_SetSwapInterval((int)swapOnVSync);
+		SDL_GL_SetSwapInterval(swapOnVSync ? swapInterval : 0);
 	}
 #endif
 	SDL_GL_SwapWindow(window);
diff --git a/core/wsi/sdl.h b/core/wsi/sdl.h
index d1f9c5b29..83ec28d0d 100644
--- a/core/wsi/sdl.h
+++ b/core/wsi/sdl.h
@@ -46,6 +46,7 @@ private:
 	SDL_Window* window = nullptr;
 	SDL_GLContext glcontext = nullptr;
 	bool swapOnVSync = false;
+	int swapInterval = 1;
 };
 
 extern SDLGLGraphicsContext theGLContext;