Implement Vsync for SDL device (#16683)

builtin/settingtypes.txt

@@ -456,7 +456,9 @@ pause_on_lost_focus (Pause on lost window focus) bool false
 #    to not waste CPU power for no benefit.
 fps_max (Maximum FPS) int 60 1 4294967295
 
-#    Vertical screen synchronization. Your system may still force VSync on even if this is disabled.
+#    Vertical screen synchronization.
+#    Note: A restart is required after changing this!
+#    Your system may still force VSync and ignore this setting.
 vsync (VSync) bool false
 
 #    Maximum FPS when the window is not focused.

irr/src/CIrrDeviceSDL.cpp

@@ -779,6 +779,8 @@ void CIrrDeviceSDL::createDriver()
 	}
 
 	ContextManager = new video::CSDLManager(this);
+	ContextManager->initialize(CreationParams, {});
+
 	switch (CreationParams.DriverType) {
 	case video::EDT_OPENGL:
 		VideoDriver = video::createOpenGLDriver(CreationParams, FileSystem, ContextManager);

irr/src/CSDLManager.cpp

@@ -7,6 +7,7 @@
 #if defined(_IRR_COMPILE_WITH_SDL_DEVICE_)
 
 #include "CIrrDeviceSDL.h"
+#include "os.h"
 
 namespace video
 {
@@ -18,6 +19,14 @@ CSDLManager::CSDLManager(CIrrDeviceSDL *device) :
 bool CSDLManager::initialize(const SIrrlichtCreationParameters &params, const SExposedVideoData &data)
 {
 	Data = data;
+	int interval = params.Vsync ? 1 : 0;
+#ifdef _IRR_USE_SDL3_
+	bool ok = SDL_GL_SetSwapInterval(interval);
+#else
+	bool ok = SDL_GL_SetSwapInterval(interval) == 0;
+#endif
+	if (!ok)
+		os::Printer::log("Setting GL swap interval failed");
 	return true;
 }