Feature: allow a toggle to enable/disable vsync

Vsync should be off by default, as for most players it will be
better to play without vsync. Exception exist, mainly people who
play in fullscreen mode.

10 files changed, 68 insertions, 12 deletions

diff --git a/src/lang/english.txt b/src/lang/english.txt
index 0f4b4a99d..9bccd86df 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -1006,6 +1006,9 @@ STR_GAME_OPTIONS_VIDEO_ACCELERATION                             :{BLACK}Hardware
 STR_GAME_OPTIONS_VIDEO_ACCELERATION_TOOLTIP                     :{BLACK}Check this box to allow OpenTTD to try to use hardware acceleration. A changed setting will only be applied upon game restart
 STR_GAME_OPTIONS_VIDEO_ACCELERATION_RESTART                     :{WHITE}The setting will only take effect after a game restart
 
+STR_GAME_OPTIONS_VIDEO_VSYNC                                    :{BLACK}VSync
+STR_GAME_OPTIONS_VIDEO_VSYNC_TOOLTIP                            :{BLACK}Check this box to v-sync the screen. A changed setting will only be applied upon game restart. Only works with hardware acceleration enabled
+
 STR_GAME_OPTIONS_GUI_ZOOM_FRAME                                 :{BLACK}Interface size
 STR_GAME_OPTIONS_GUI_ZOOM_DROPDOWN_TOOLTIP                      :{BLACK}Select the interface element size to use
 
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 6788d1ae3..afc8f080e 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -458,6 +458,19 @@ struct GameOptionsWindow : Window {
 				_video_hw_accel = !_video_hw_accel;
 				ShowErrorMessage(STR_GAME_OPTIONS_VIDEO_ACCELERATION_RESTART, INVALID_STRING_ID, WL_INFO);
 				this->SetWidgetLoweredState(WID_GO_VIDEO_ACCEL_BUTTON, _video_hw_accel);
+#ifndef __APPLE__
+				this->SetWidgetDisabledState(WID_GO_VIDEO_VSYNC_BUTTON, !_video_hw_accel);
+#endif
+				this->SetDirty();
+				break;
+
+			case WID_GO_VIDEO_VSYNC_BUTTON:
+				if (!_video_hw_accel) break;
+
+				_video_vsync = !_video_vsync;
+				VideoDriver::GetInstance()->ToggleVsync(_video_vsync);
+
+				this->SetWidgetLoweredState(WID_GO_VIDEO_VSYNC_BUTTON, _video_vsync);
 				this->SetDirty();
 				break;
 
@@ -598,6 +611,11 @@ struct GameOptionsWindow : Window {
 		this->SetWidgetLoweredState(WID_GO_FULLSCREEN_BUTTON, _fullscreen);
 		this->SetWidgetLoweredState(WID_GO_VIDEO_ACCEL_BUTTON, _video_hw_accel);
 
+#ifndef __APPLE__
+		this->SetWidgetLoweredState(WID_GO_VIDEO_VSYNC_BUTTON, _video_vsync);
+		this->SetWidgetDisabledState(WID_GO_VIDEO_VSYNC_BUTTON, !_video_hw_accel);
+#endif
+
 		bool missing_files = BaseGraphics::GetUsedSet()->GetNumMissing() == 0;
 		this->GetWidget<NWidgetCore>(WID_GO_BASE_GRF_STATUS)->SetDataTip(missing_files ? STR_EMPTY : STR_GAME_OPTIONS_BASE_GRF_STATUS, STR_NULL);
 
@@ -647,7 +665,10 @@ static const NWidgetPart _nested_game_options_widgets[] = {
 					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_RESOLUTION, STR_NULL), SetPadding(0, 0, 2, 0),
 					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_REFRESH_RATE, STR_NULL), SetPadding(0, 0, 2, 0),
 					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_FULLSCREEN, STR_NULL), SetPadding(0, 0, 2, 0),
-					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_VIDEO_ACCELERATION, STR_NULL),
+					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_VIDEO_ACCELERATION, STR_NULL), SetPadding(0, 0, 2, 0),
+#ifndef __APPLE__
+					NWidget(WWT_TEXT, COLOUR_GREY), SetMinimalSize(0, 12), SetFill(1, 0), SetDataTip(STR_GAME_OPTIONS_VIDEO_VSYNC, STR_NULL),
+#endif
 				EndContainer(),
 				NWidget(NWID_VERTICAL),
 					NWidget(WWT_DROPDOWN, COLOUR_GREY, WID_GO_RESOLUTION_DROPDOWN), SetMinimalSize(100, 12), SetDataTip(STR_BLACK_STRING, STR_GAME_OPTIONS_RESOLUTION_TOOLTIP), SetFill(1, 0), SetPadding(0, 0, 2, 0),
@@ -656,10 +677,16 @@ static const NWidgetPart _nested_game_options_widgets[] = {
 						NWidget(NWID_SPACER), SetMinimalSize(1, 0), SetFill(1, 0),
 						NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_GO_FULLSCREEN_BUTTON), SetMinimalSize(21, 9), SetDataTip(STR_EMPTY, STR_GAME_OPTIONS_FULLSCREEN_TOOLTIP),
 					EndContainer(),
-					NWidget(NWID_HORIZONTAL),
+					NWidget(NWID_HORIZONTAL), SetPadding(0, 0, 2, 0),
 						NWidget(NWID_SPACER), SetMinimalSize(1, 0), SetFill(1, 0),
 						NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_GO_VIDEO_ACCEL_BUTTON), SetMinimalSize(21, 9), SetDataTip(STR_EMPTY, STR_GAME_OPTIONS_VIDEO_ACCELERATION_TOOLTIP),
 					EndContainer(),
+#ifndef __APPLE__
+					NWidget(NWID_HORIZONTAL),
+						NWidget(NWID_SPACER), SetMinimalSize(1, 0), SetFill(1, 0),
+						NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_GO_VIDEO_VSYNC_BUTTON), SetMinimalSize(21, 9), SetDataTip(STR_EMPTY, STR_GAME_OPTIONS_VIDEO_VSYNC_TOOLTIP),
+					EndContainer(),
+#endif
 				EndContainer(),
 			EndContainer(),
 		EndContainer(),
diff --git a/src/table/misc_settings.ini b/src/table/misc_settings.ini
index 9286d1c95..49a4caa14 100644
--- a/src/table/misc_settings.ini
+++ b/src/table/misc_settings.ini
@@ -77,6 +77,12 @@ var      = _video_hw_accel
 def      = true
 cat      = SC_BASIC
 
+[SDTG_BOOL]
+name     = ""video_vsync""
+var      = _video_vsync
+def      = false
+cat      = SC_BASIC
+
 [SDTG_OMANY]
 name     = ""support8bpp""
 type     = SLE_UINT8
diff --git a/src/video/sdl2_opengl_v.cpp b/src/video/sdl2_opengl_v.cpp
index 5df283751..08718a01e 100644
--- a/src/video/sdl2_opengl_v.cpp
+++ b/src/video/sdl2_opengl_v.cpp
@@ -70,8 +70,6 @@ const char *VideoDriver_SDL_OpenGL::Start(const StringList &param)
 	SDL_GetWindowSize(this->sdl_window, &w, &h);
 	this->ClientSizeChanged(w, h, true);
 
-	SDL_GL_SetSwapInterval(GetDriverParamBool(param, "vsync") ? 1 : 0);
-
 	return nullptr;
 }
 
@@ -91,6 +89,11 @@ void VideoDriver_SDL_OpenGL::DestroyContext()
 	}
 }
 
+void VideoDriver_SDL_OpenGL::ToggleVsync(bool vsync)
+{
+	SDL_GL_SetSwapInterval(vsync);
+}
+
 const char *VideoDriver_SDL_OpenGL::AllocateContext()
 {
 	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
@@ -107,6 +110,8 @@ const char *VideoDriver_SDL_OpenGL::AllocateContext()
 	this->gl_context = SDL_GL_CreateContext(this->sdl_window);
 	if (this->gl_context == nullptr) return "SDL2: Can't active GL context";
 
+	ToggleVsync(_video_vsync);
+
 	return OpenGLBackend::Create(&GetOGLProcAddressCallback);
 }
 
diff --git a/src/video/sdl2_opengl_v.h b/src/video/sdl2_opengl_v.h
index f749b1f45..c7e647ca8 100644
--- a/src/video/sdl2_opengl_v.h
+++ b/src/video/sdl2_opengl_v.h
@@ -29,6 +29,8 @@ public:
 	bool HasAnimBuffer() override { return true; }
 	uint8 *GetAnimBuffer() override { return this->anim_buffer; }
 
+	void ToggleVsync(bool vsync) override;
+
 	const char *GetName() const override { return "sdl-opengl"; }
 
 protected:
diff --git a/src/video/video_driver.cpp b/src/video/video_driver.cpp
index bee67e1ea..eaff0b741 100644
--- a/src/video/video_driver.cpp
+++ b/src/video/video_driver.cpp
@@ -21,6 +21,7 @@
 #include "video_driver.hpp"
 
 bool _video_hw_accel; ///< Whether to consider hardware accelerated video drivers.
+bool _video_vsync; ///< Whether we should use vsync (only if _video_hw_accel is enabled).
 
 void VideoDriver::GameLoop()
 {
diff --git a/src/video/video_driver.hpp b/src/video/video_driver.hpp
index 7a859565a..f143b61a8 100644
--- a/src/video/video_driver.hpp
+++ b/src/video/video_driver.hpp
@@ -28,6 +28,7 @@ extern std::vector<Dimension> _resolutions;
 extern Dimension _cur_resolution;
 extern bool _rightclick_emulate;
 extern bool _video_hw_accel;
+extern bool _video_vsync;
 
 /** The base of all video drivers. */
 class VideoDriver : public Driver {
@@ -67,6 +68,12 @@ public:
 	virtual bool ToggleFullscreen(bool fullscreen) = 0;
 
 	/**
+	 * Change the vsync setting.
+	 * @param vsync The new setting.
+	 */
+	virtual void ToggleVsync(bool vsync) {}
+
+	/**
 	 * Callback invoked after the blitter was changed.
 	 * @return True if no error.
 	 */
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
index 426d74c0a..467478461 100644
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -1290,7 +1290,6 @@ const char *VideoDriver_Win32OpenGL::Start(const StringList &param)
 	if (BlitterFactory::GetCurrentBlitter()->GetScreenDepth() == 0) return "Only real blitters supported";
 
 	Dimension old_res = _cur_resolution; // Save current screen resolution in case of errors, as MakeWindow invalidates it.
-	this->vsync = GetDriverParamBool(param, "vsync");
 
 	LoadWGLExtensions();
 
@@ -1335,6 +1334,15 @@ void VideoDriver_Win32OpenGL::DestroyContext()
 	}
 }
 
+void VideoDriver_Win32OpenGL::ToggleVsync(bool vsync)
+{
+	if (_wglSwapIntervalEXT != nullptr) {
+		_wglSwapIntervalEXT(vsync);
+	} else if (vsync) {
+		DEBUG(driver, 0, "OpenGL: Vsync requested, but not supported by driver");
+	}
+}
+
 const char *VideoDriver_Win32OpenGL::AllocateContext()
 {
 	this->dc = GetDC(this->main_wnd);
@@ -1363,12 +1371,7 @@ const char *VideoDriver_Win32OpenGL::AllocateContext()
 	}
 	if (!wglMakeCurrent(this->dc, rc)) return "Can't active GL context";
 
-	/* Enable/disable Vsync if supported. */
-	if (_wglSwapIntervalEXT != nullptr) {
-		_wglSwapIntervalEXT(this->vsync ? 1 : 0);
-	} else if (vsync) {
-		DEBUG(driver, 0, "OpenGL: Vsync requested, but not supported by driver");
-	}
+	this->ToggleVsync(_video_vsync);
 
 	this->gl_rc = rc;
 	return OpenGLBackend::Create(&GetOGLProcAddressCallback);
diff --git a/src/video/win32_v.h b/src/video/win32_v.h
index f6ca291f1..8c63aeedf 100644
--- a/src/video/win32_v.h
+++ b/src/video/win32_v.h
@@ -138,12 +138,13 @@ public:
 	bool HasAnimBuffer() override { return true; }
 	uint8 *GetAnimBuffer() override { return this->anim_buffer; }
 
+	void ToggleVsync(bool vsync) override;
+
 	const char *GetName() const override { return "win32-opengl"; }
 
 protected:
 	HDC    dc;          ///< Window device context.
 	HGLRC  gl_rc;       ///< OpenGL context.
-	bool   vsync;       ///< Enable VSync?
 	uint8 *anim_buffer; ///< Animation buffer from OpenGL back-end.
 
 	uint8 GetFullscreenBpp() override { return 32; } // OpenGL is always 32 bpp.
diff --git a/src/widgets/settings_widget.h b/src/widgets/settings_widget.h
index ae9c22c1a..c89792734 100644
--- a/src/widgets/settings_widget.h
+++ b/src/widgets/settings_widget.h
@@ -35,6 +35,7 @@ enum GameOptionsWidgets {
 	WID_GO_BASE_MUSIC_DESCRIPTION = WID_GO_BASE_MUSIC_TEXTFILE + TFT_END, ///< Description of selected base music set.
 	WID_GO_FONT_ZOOM_DROPDOWN,     ///< Dropdown for the font zoom level.
 	WID_GO_VIDEO_ACCEL_BUTTON,     ///< Toggle for video acceleration.
+	WID_GO_VIDEO_VSYNC_BUTTON,     ///< Toggle for video vsync.
 	WID_GO_REFRESH_RATE_DROPDOWN,  ///< Dropdown for all available refresh rates.
 };