From 1e18c3fb9f45afbd9dce4c86b6c942eea8ab5a71 Mon Sep 17 00:00:00 2001
From: rogerman <rogerman@users.noreply.github.com>
Date: Mon, 19 Nov 2018 02:49:31 -0800
Subject: [PATCH] Windows Port: When running OpenGL display method, properly
 initialize V-sync to match wantVsync rather than assuming that the default
 setting for wantVsync will match the default setting of the video driver.

---
 desmume/src/frontend/windows/ogl_display.cpp | 23 +++++++++++++++-----
 desmume/src/frontend/windows/ogl_display.h   |  2 +-
 2 files changed, 18 insertions(+), 7 deletions(-)
 mode change 100644 => 100755 desmume/src/frontend/windows/ogl_display.cpp
 mode change 100644 => 100755 desmume/src/frontend/windows/ogl_display.h

diff --git a/desmume/src/frontend/windows/ogl_display.cpp b/desmume/src/frontend/windows/ogl_display.cpp
old mode 100644
new mode 100755
index 107f8ef38..acba8d611
--- a/desmume/src/frontend/windows/ogl_display.cpp
+++ b/desmume/src/frontend/windows/ogl_display.cpp
@@ -26,6 +26,17 @@ bool GLDISPLAY::initialize(HWND hwnd)
 	if (initContext(hwnd, &privateContext))
 	{
 		this->hwnd = hwnd;
+		privateDC = GetDC(hwnd);
+		wglMakeCurrent(privateDC, privateContext);
+		
+		// Certain video drivers may try to set the V-sync setting to whatever they want on
+		// initialization, and so we can't assume that wantVsync will match whatever the video
+		// driver is doing.
+		//
+		// And so we need to force the V-sync to be whatever default value wantVsync is in
+		// order to ensure that the actual V-sync setting in OpenGL matches wantVsync.
+		this->_setvsync(wantVsync);
+
 		return true;
 	}
 	else
@@ -49,11 +60,8 @@ bool GLDISPLAY::WGLExtensionSupported(const char *extension_name)
 	// extension is supported
 	return true;
 }
-void GLDISPLAY::_setvsync()
+void GLDISPLAY::_setvsync(bool isVsyncEnabled)
 {
-	//even if it doesn't work, we'll track it
-	haveVsync = wantVsync;
-
 	if (!WGLExtensionSupported("WGL_EXT_swap_control")) return;
 
 	//http://stackoverflow.com/questions/589064/how-to-enable-vertical-sync-in-opengl
@@ -67,7 +75,7 @@ void GLDISPLAY::_setvsync()
 		wglGetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC)wglGetProcAddress("wglGetSwapIntervalEXT");
 	}
 
-	wglSwapIntervalEXT(wantVsync ? 1 : 0);
+	wglSwapIntervalEXT(isVsyncEnabled ? 1 : 0);
 }
 
 
@@ -105,7 +113,10 @@ bool GLDISPLAY::begin(HWND hwnd)
 
 	//go ahead and sync the vsync setting while we have the context
 	if (wantVsync != haveVsync)
-		_setvsync();
+	{
+		_setvsync(wantVsync);
+		haveVsync = wantVsync;
+	}
 
 	if (filter)
 	{
diff --git a/desmume/src/frontend/windows/ogl_display.h b/desmume/src/frontend/windows/ogl_display.h
old mode 100644
new mode 100755
index 0b84c26c9..6627db26e
--- a/desmume/src/frontend/windows/ogl_display.h
+++ b/desmume/src/frontend/windows/ogl_display.h
@@ -34,7 +34,7 @@ private:
 	HWND hwnd;
 	bool initialize(HWND hwnd);
 	bool WGLExtensionSupported(const char *extension_name);
-	void _setvsync();
+	void _setvsync(bool isVsyncEnabled);
 
 public:
 	bool active;