Fix Vsync Via Compositor causing halved refresh rate when vsync is forced by the graphics driver

Add check to prevent compositor sync if the graphics driver is forcing vsync.

Fixes #35038.

(Addendum: this PR does not negatively impact users unaffected by #35038.)

2 files changed, 4 insertions, 1 deletions

diff --git a/platform/windows/context_gl_windows.cpp b/platform/windows/context_gl_windows.cpp
index 21d954a736..434d685250 100644
--- a/platform/windows/context_gl_windows.cpp
+++ b/platform/windows/context_gl_windows.cpp
@@ -89,7 +89,7 @@ void ContextGL_Windows::swap_buffers() {
 	if (use_vsync) {
 		bool vsync_via_compositor_now = should_vsync_via_compositor();
 
-		if (vsync_via_compositor_now) {
+		if (vsync_via_compositor_now && wglGetSwapIntervalEXT() == 0) {
 			DwmFlush();
 		}
 
@@ -205,6 +205,7 @@ Error ContextGL_Windows::initialize() {
 	}
 
 	wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress("wglSwapIntervalEXT");
+	wglGetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC)wglGetProcAddress("wglGetSwapIntervalEXT");
 	//glWrapperInit(wrapper_get_proc_address);
 
 	return OK;
diff --git a/platform/windows/context_gl_windows.h b/platform/windows/context_gl_windows.h
index 0c6a6d1814..280c5a1e3c 100644
--- a/platform/windows/context_gl_windows.h
+++ b/platform/windows/context_gl_windows.h
@@ -41,6 +41,7 @@
 #include <windows.h>
 
 typedef bool(APIENTRY *PFNWGLSWAPINTERVALEXTPROC)(int interval);
+typedef int(APIENTRY *PFNWGLGETSWAPINTERVALEXTPROC)(void);
 
 class ContextGL_Windows {
 
@@ -53,6 +54,7 @@ class ContextGL_Windows {
 	bool vsync_via_compositor;
 
 	PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT;
+	PFNWGLGETSWAPINTERVALEXTPROC wglGetSwapIntervalEXT;
 
 	static bool should_vsync_via_compositor();