7 files changed, 861 insertions, 4 deletions

diff --git a/backends/graphics/opengl/opengl-graphics.cpp b/backends/graphics/opengl/opengl-graphics.cpp
index 7ea880c92e..87d6d3c2e5 100644
--- a/backends/graphics/opengl/opengl-graphics.cpp
+++ b/backends/graphics/opengl/opengl-graphics.cpp
@@ -106,6 +106,10 @@ const OSystem::GraphicsMode glGraphicsModes[] = {
 
 } // End of anonymous namespace
 
+const OSystem::GraphicsMode *OpenGLGraphicsManager::supportedGraphicsModes() {
+	return glGraphicsModes;
+}
+
 const OSystem::GraphicsMode *OpenGLGraphicsManager::getSupportedGraphicsModes() const {
 	return glGraphicsModes;
 }
diff --git a/backends/graphics/opengl/opengl-graphics.h b/backends/graphics/opengl/opengl-graphics.h
index e21bda4b8a..5aa521cb7a 100644
--- a/backends/graphics/opengl/opengl-graphics.h
+++ b/backends/graphics/opengl/opengl-graphics.h
@@ -47,6 +47,10 @@ public:
 	virtual void setFeatureState(OSystem::Feature f, bool enable);
 	virtual bool getFeatureState(OSystem::Feature f);
 
+	// HACK: This is required for the SDL backend to switch between OpenGL SDL
+	// and Surface SDL.
+	static const OSystem::GraphicsMode *supportedGraphicsModes();
+
 	virtual const OSystem::GraphicsMode *getSupportedGraphicsModes() const;
 	virtual int getDefaultGraphicsMode() const;
 	virtual bool setGraphicsMode(int mode);
diff --git a/backends/graphics/openglsdl/openglsdl-graphics.cpp b/backends/graphics/openglsdl/openglsdl-graphics.cpp
new file mode 100644
index 0000000000..ce6d7ec7f0
--- /dev/null
+++ b/backends/graphics/openglsdl/openglsdl-graphics.cpp
@@ -0,0 +1,487 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "backends/graphics/openglsdl/openglsdl-graphics.h"
+
+#include "common/textconsole.h"
+#include "common/config-manager.h"
+
+OpenGLSdlGraphicsManager::OpenGLSdlGraphicsManager(uint desktopWidth, uint desktopHeight, SdlEventSource *eventSource)
+    : SdlGraphicsManager(eventSource), _lastVideoModeLoad(0), _hwScreen(nullptr), _lastRequestedWidth(0), _lastRequestedHeight(0),
+      _graphicsScale(2), _ignoreLoadVideoMode(false), _gotResize(false), _wantsFullScreen(false), _ignoreResizeEvents(0),
+      _desiredFullscreenWidth(0), _desiredFullscreenHeight(0) {
+	// Initialize SDL video subsystem
+	if (SDL_InitSubSystem(SDL_INIT_VIDEO) == -1) {
+		error("Could not initialize SDL: %s", SDL_GetError());
+	}
+
+	// Setup OpenGL attributes for SDL
+	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
+	SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
+	SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
+	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
+	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+
+	// This is also called in initSDL(), but initializing graphics
+	// may reset it.
+	SDL_EnableUNICODE(1);
+
+	// Disable OS cursor
+	SDL_ShowCursor(SDL_DISABLE);
+
+	// Retrieve a list of working fullscreen modes
+	const SDL_Rect *const *availableModes = SDL_ListModes(NULL, SDL_OPENGL | SDL_FULLSCREEN);
+	if (availableModes != (void *)-1) {
+		for (;*availableModes; ++availableModes) {
+			const SDL_Rect *mode = *availableModes;
+
+			_fullscreenVideoModes.push_back(VideoMode(mode->w, mode->h));
+		}
+
+		// Sort the modes in ascending order.
+		Common::sort(_fullscreenVideoModes.begin(), _fullscreenVideoModes.end());
+	}
+
+	// In case SDL is fine with every mode we will force the desktop mode.
+	// TODO? We could also try to add some default resolutions here.
+	if (_fullscreenVideoModes.empty() && desktopWidth && desktopHeight) {
+		_fullscreenVideoModes.push_back(VideoMode(desktopWidth, desktopHeight));
+	}
+
+	// Get information about display sizes from the previous runs.
+	if (ConfMan.hasKey("last_fullscreen_mode_width", Common::ConfigManager::kApplicationDomain) && ConfMan.hasKey("last_fullscreen_mode_height", Common::ConfigManager::kApplicationDomain)) {
+		_desiredFullscreenWidth  = ConfMan.getInt("last_fullscreen_mode_width", Common::ConfigManager::kApplicationDomain);
+		_desiredFullscreenHeight = ConfMan.getInt("last_fullscreen_mode_height", Common::ConfigManager::kApplicationDomain);
+	} else {
+		// Use the desktop resolutions when no previous default has been setup.
+		_desiredFullscreenWidth  = desktopWidth;
+		_desiredFullscreenHeight = desktopHeight;
+	}
+}
+
+OpenGLSdlGraphicsManager::~OpenGLSdlGraphicsManager() {
+	// Unregister the event observer
+	if (g_system->getEventManager()->getEventDispatcher()) {
+		g_system->getEventManager()->getEventDispatcher()->unregisterObserver(this);
+	}
+}
+
+void OpenGLSdlGraphicsManager::initEventObserver() {
+	// Register the graphics manager as a event observer
+	g_system->getEventManager()->getEventDispatcher()->registerObserver(this, 10, false);
+}
+
+bool OpenGLSdlGraphicsManager::hasFeature(OSystem::Feature f) {
+	switch (f) {
+	case OSystem::kFeatureFullscreenMode:
+	case OSystem::kFeatureIconifyWindow:
+		return true;
+
+	default:
+		return OpenGLGraphicsManager::hasFeature(f);
+	}
+}
+
+void OpenGLSdlGraphicsManager::setFeatureState(OSystem::Feature f, bool enable) {
+	switch (f) {
+	case OSystem::kFeatureFullscreenMode:
+		assert(getTransactionMode() != kTransactionNone);
+		_wantsFullScreen = enable;
+		// When we switch to windowed mode we will ignore resize events. This
+		// avoids bad resizes to the (former) fullscreen resolution.
+		if (!enable) {
+			_ignoreResizeEvents = 10;
+		}
+		break;
+
+	case OSystem::kFeatureIconifyWindow:
+		if (enable) {
+			SDL_WM_IconifyWindow();
+		}
+		break;
+
+	default:
+		OpenGLGraphicsManager::setFeatureState(f, enable);
+	}
+}
+
+bool OpenGLSdlGraphicsManager::getFeatureState(OSystem::Feature f) {
+	switch (f) {
+	case OSystem::kFeatureFullscreenMode:
+		if (_hwScreen) {
+			return (_hwScreen->flags & SDL_FULLSCREEN) != 0;
+		} else {
+			return _wantsFullScreen;
+		}
+
+	default:
+		return OpenGLGraphicsManager::getFeatureState(f);
+	}
+}
+
+bool OpenGLSdlGraphicsManager::setGraphicsMode(int mode) {
+	// HACK: This is stupid but the SurfaceSDL backend defaults to 2x. This
+	// assures that the launcher (which requests 320x200) has a reasonable
+	// size. It also makes small games have a reasonable size (i.e. at least
+	// 640x400). We follow the same logic here until we have a better way to
+	// give hints to our backend for that.
+	_graphicsScale = 2;
+
+	return OpenGLGraphicsManager::setGraphicsMode(mode);
+}
+
+void OpenGLSdlGraphicsManager::resetGraphicsScale() {
+	OpenGLGraphicsManager::resetGraphicsScale();
+
+	// HACK: See OpenGLSdlGraphicsManager::setGraphicsMode.
+	_graphicsScale = 1;
+}
+
+#ifdef USE_RGB_COLOR
+Common::List<Graphics::PixelFormat> OpenGLSdlGraphicsManager::getSupportedFormats() const {
+	Common::List<Graphics::PixelFormat> formats;
+
+	// RGBA8888
+	formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0));
+	// RGB565
+	formats.push_back(Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0));
+	// RGBA5551
+	formats.push_back(Graphics::PixelFormat(2, 5, 5, 5, 1, 11, 6, 1, 0));
+	// RGBA4444
+	formats.push_back(Graphics::PixelFormat(2, 4, 4, 4, 4, 12, 8, 4, 0));
+
+#ifndef USE_GLES
+	// ARGB8888, this should not be here, but Sword25 requires it. :-/
+	formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 16, 8, 0, 24));
+
+	// RGB555, this is used by SCUMM HE 16 bit games.
+	formats.push_back(Graphics::PixelFormat(2, 5, 5, 5, 0, 10, 5, 0, 0));
+#endif
+
+	formats.push_back(Graphics::PixelFormat::createFormatCLUT8());
+
+	return formats;
+}
+#endif
+
+void OpenGLSdlGraphicsManager::updateScreen() {
+	if (_ignoreResizeEvents) {
+		--_ignoreResizeEvents;
+	}
+
+	OpenGLGraphicsManager::updateScreen();
+
+	// Swap OpenGL buffers
+	SDL_GL_SwapBuffers();
+}
+
+void OpenGLSdlGraphicsManager::notifyVideoExpose() {
+}
+
+void OpenGLSdlGraphicsManager::notifyResize(const uint width, const uint height) {
+	if (!_ignoreResizeEvents && _hwScreen && !(_hwScreen->flags & SDL_FULLSCREEN)) {
+		// We save that we handled a resize event here. We need to know this
+		// so we do not overwrite the users requested window size whenever we
+		// switch aspect ratio or similar.
+		_gotResize = true;
+		if (!setupMode(width, height)) {
+			warning("OpenGLSdlGraphicsManager::notifyResize: Resize failed ('%s')", SDL_GetError());
+			g_system->quit();
+		}
+	}
+}
+
+void OpenGLSdlGraphicsManager::transformMouseCoordinates(Common::Point &point) {
+	adjustMousePosition(point.x, point.y);
+}
+
+void OpenGLSdlGraphicsManager::notifyMousePos(Common::Point mouse) {
+	setMousePosition(mouse.x, mouse.y);
+}
+
+void OpenGLSdlGraphicsManager::setInternalMousePosition(int x, int y) {
+	SDL_WarpMouse(x, y);
+}
+
+bool OpenGLSdlGraphicsManager::loadVideoMode(uint requestedWidth, uint requestedHeight, const Graphics::PixelFormat &format) {
+	// In some cases we might not want to load the requested video mode. This
+	// will assure that the window size is not altered.
+	if (_ignoreLoadVideoMode) {
+		_ignoreLoadVideoMode = false;
+		return true;
+	}
+
+	// This function should never be called from notifyResize thus we know
+	// that the requested size came from somewhere else.
+	_gotResize = false;
+
+	// Save the requested dimensions.
+	_lastRequestedWidth  = requestedWidth;
+	_lastRequestedHeight = requestedHeight;
+
+	// Apply the currently saved scale setting.
+	requestedWidth  *= _graphicsScale;
+	requestedHeight *= _graphicsScale;
+
+	// Set up the mode.
+	return setupMode(requestedWidth, requestedHeight);
+}
+
+bool OpenGLSdlGraphicsManager::setupMode(uint width, uint height) {
+	// In case we request a fullscreen mode we will use the mode the user
+	// has chosen last time or the biggest mode available.
+	if (_wantsFullScreen) {
+		if (_desiredFullscreenWidth && _desiredFullscreenHeight) {
+			// In case only a distinct set of modes is available we check
+			// whether the requested mode is actually available.
+			if (!_fullscreenVideoModes.empty()) {
+				VideoModeArray::const_iterator i = Common::find(_fullscreenVideoModes.begin(),
+				                                                _fullscreenVideoModes.end(),
+				                                                VideoMode(_desiredFullscreenWidth, _desiredFullscreenHeight));
+				// It's not available fall back to default.
+				if (i == _fullscreenVideoModes.end()) {
+					_desiredFullscreenWidth = 0;
+					_desiredFullscreenHeight = 0;
+				}
+			}
+		}
+
+		// In case no desired mode has been set we default to the biggest mode
+		// available or the requested mode in case we don't know any
+		// any fullscreen modes.
+		if (!_desiredFullscreenWidth || !_desiredFullscreenHeight) {
+			if (!_fullscreenVideoModes.empty()) {
+				VideoModeArray::const_iterator i = _fullscreenVideoModes.end();
+				--i;
+	
+				_desiredFullscreenWidth  = i->width;
+				_desiredFullscreenHeight = i->height;
+			} else {
+				_desiredFullscreenWidth  = width;
+				_desiredFullscreenHeight = height;
+			}
+		}
+
+		// Remember our choice.
+		ConfMan.setInt("last_fullscreen_mode_width", _desiredFullscreenWidth, Common::ConfigManager::kApplicationDomain);
+		ConfMan.setInt("last_fullscreen_mode_height", _desiredFullscreenHeight, Common::ConfigManager::kApplicationDomain);
+
+		// Use our choice.
+		width  = _desiredFullscreenWidth;
+		height = _desiredFullscreenHeight;
+	}
+
+	// WORKAROUND: Working around infamous SDL bugs when switching
+	// resolutions too fast. This might cause the event system to supply
+	// incorrect mouse position events otherwise.
+	// Reference: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=665779
+	const uint32 curTime = SDL_GetTicks();
+	if (_hwScreen && (curTime < _lastVideoModeLoad || curTime - _lastVideoModeLoad < 100)) {
+		for (int i = 10; i > 0; --i) {
+			SDL_PumpEvents();
+			SDL_Delay(10);
+		}
+	}
+	_lastVideoModeLoad = curTime;
+
+	uint32 flags = SDL_OPENGL;
+	if (_wantsFullScreen) {
+		flags |= SDL_FULLSCREEN;
+	} else {
+		flags |= SDL_RESIZABLE;
+	}
+
+	_hwScreen = SDL_SetVideoMode(width, height, 32, flags);
+
+	if (!_hwScreen) {
+		// We treat fullscreen requests as a "hint" for now. This means in
+		// case it is not available we simply ignore it.
+		if (_wantsFullScreen) {
+			_hwScreen = SDL_SetVideoMode(width, height, 32, SDL_OPENGL | SDL_RESIZABLE);
+		}
+	}
+
+	if (_hwScreen) {
+		const Graphics::PixelFormat rgba8888 = Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0);
+		notifyContextChange(rgba8888, rgba8888);
+		setActualScreenSize(_hwScreen->w, _hwScreen->h);
+	}
+
+	return _hwScreen != nullptr;
+}
+
+bool OpenGLSdlGraphicsManager::notifyEvent(const Common::Event &event) {
+	switch (event.type) {
+	case Common::EVENT_KEYUP:
+		return isHotkey(event);
+
+	case Common::EVENT_KEYDOWN:
+		if (event.kbd.hasFlags(Common::KBD_ALT)) {
+			if (   event.kbd.keycode == Common::KEYCODE_RETURN
+			    || event.kbd.keycode == (Common::KeyCode)SDLK_KP_ENTER) {
+				// Alt-Return and Alt-Enter toggle full screen mode
+				beginGFXTransaction();
+					setFeatureState(OSystem::kFeatureFullscreenMode, !getFeatureState(OSystem::kFeatureFullscreenMode));
+				endGFXTransaction();
+				return true;
+			}
+		} else if (event.kbd.hasFlags(Common::KBD_CTRL | Common::KBD_ALT)) {
+			if (   event.kbd.keycode == Common::KEYCODE_PLUS || event.kbd.keycode == Common::KEYCODE_MINUS
+			    || event.kbd.keycode == Common::KEYCODE_KP_PLUS || event.kbd.keycode == Common::KEYCODE_KP_MINUS) {
+				// Ctrl+Alt+Plus/Minus Increase/decrease the size
+				const int direction = (event.kbd.keycode == Common::KEYCODE_PLUS || event.kbd.keycode == Common::KEYCODE_KP_PLUS) ? +1 : -1;
+
+				if (getFeatureState(OSystem::kFeatureFullscreenMode)) {
+					// In case we are in fullscreen we will choose the previous
+					// or next mode.
+
+					// In case no modes are available we do nothing.
+					if (_fullscreenVideoModes.empty()) {
+						return true;
+					}
+
+					// Look for the current mode.
+					VideoModeArray::const_iterator i = Common::find(_fullscreenVideoModes.begin(),
+					                                                _fullscreenVideoModes.end(),
+					                                                VideoMode(_desiredFullscreenWidth, _desiredFullscreenHeight));
+					if (i == _fullscreenVideoModes.end()) {
+						return true;
+					}
+
+					// Cycle through the modes in the specified direction.
+					if (direction > 0) {
+						++i;
+						if (i == _fullscreenVideoModes.end()) {
+							i = _fullscreenVideoModes.begin();
+						}
+					} else {
+						if (i == _fullscreenVideoModes.begin()) {
+							i = _fullscreenVideoModes.end();
+						}
+						--i;
+					}
+
+					_desiredFullscreenWidth  = i->width;
+					_desiredFullscreenHeight = i->height;
+
+					// Try to setup the mode.
+					if (!setupMode(_lastRequestedWidth, _lastRequestedHeight)) {
+						warning("OpenGLSdlGraphicsManager::notifyEvent: Fullscreen resize failed ('%s')", SDL_GetError());
+						g_system->quit();
+					}
+				} else {
+					// Calculate the next scaling setting. We approximate the
+					// current scale setting in case the user resized the
+					// window. Then we apply the direction change.
+					_graphicsScale = MAX<int>(_hwScreen->w / _lastRequestedWidth, _hwScreen->h / _lastRequestedHeight);
+					_graphicsScale = MAX<int>(_graphicsScale + direction, 1);
+
+					// Since we overwrite a user resize here we reset its
+					// flag here. This makes enabling AR smoother because it
+					// will change the window size like in surface SDL.
+					_gotResize = false;
+
+					// Try to setup the mode.
+					if (!setupMode(_lastRequestedWidth * _graphicsScale, _lastRequestedHeight * _graphicsScale)) {
+						warning("OpenGLSdlGraphicsManager::notifyEvent: Window resize failed ('%s')", SDL_GetError());
+						g_system->quit();
+					}
+				}
+
+				return true;
+			} else if (event.kbd.keycode == Common::KEYCODE_a) {
+				// In case the user changed the window size manually we will
+				// not change the window size again here.
+				_ignoreLoadVideoMode = _gotResize;
+
+				// Ctrl+Alt+a toggles the aspect ratio correction state.
+				beginGFXTransaction();
+					setFeatureState(OSystem::kFeatureAspectRatioCorrection, !getFeatureState(OSystem::kFeatureAspectRatioCorrection));
+				endGFXTransaction();
+
+				// Make sure we do not ignore the next resize. This
+				// effectively checks whether loadVideoMode has been called.
+				assert(!_ignoreLoadVideoMode);
+
+				return true;
+			} else if (event.kbd.keycode == Common::KEYCODE_f) {
+				// Ctrl+Alt+f toggles the graphics modes.
+
+				// We are crazy we will allow the OpenGL base class to
+				// introduce new graphics modes like shaders for special
+				// filtering. If some other OpenGL subclass needs this,
+				// we can think of refactoring this.
+				int mode = getGraphicsMode();
+				const OSystem::GraphicsMode *supportedModes = getSupportedGraphicsModes();
+				const OSystem::GraphicsMode *modeDesc = nullptr;
+
+				// Search the current mode.
+				for (; supportedModes->name; ++supportedModes) {
+					if (supportedModes->id == mode) {
+						modeDesc = supportedModes;
+						break;
+					}
+				}
+				assert(modeDesc);
+
+				// Try to use the next mode in the list.
+				++modeDesc;
+				if (!modeDesc->name) {
+					modeDesc = getSupportedGraphicsModes();
+				}
+
+				// Never ever try to resize the window when we simply want to
+				// switch the graphics mode. This assures that the window size
+				// does not change.
+				_ignoreLoadVideoMode = true;
+
+				beginGFXTransaction();
+					setGraphicsMode(modeDesc->id);
+				endGFXTransaction();
+
+				// Make sure we do not ignore the next resize. This
+				// effectively checks whether loadVideoMode has been called.
+				assert(!_ignoreLoadVideoMode);
+
+				return true;
+			}
+		}
+		// Fall through
+
+	default:
+		return false;
+	}
+}
+
+bool OpenGLSdlGraphicsManager::isHotkey(const Common::Event &event) {
+	if (event.kbd.hasFlags(Common::KBD_ALT)) {
+		return    event.kbd.keycode == Common::KEYCODE_RETURN
+		       || event.kbd.keycode == (Common::KeyCode)SDLK_KP_ENTER;
+	} else if (event.kbd.hasFlags(Common::KBD_CTRL | Common::KBD_ALT)) {
+		return    event.kbd.keycode == Common::KEYCODE_PLUS || event.kbd.keycode == Common::KEYCODE_MINUS
+		       || event.kbd.keycode == Common::KEYCODE_KP_PLUS || event.kbd.keycode == Common::KEYCODE_KP_MINUS
+		       || event.kbd.keycode == Common::KEYCODE_a
+		       || event.kbd.keycode == Common::KEYCODE_f;
+	}
+
+	return false;
+}
diff --git a/backends/graphics/openglsdl/openglsdl-graphics.h b/backends/graphics/openglsdl/openglsdl-graphics.h
new file mode 100644
index 0000000000..0644f27602
--- /dev/null
+++ b/backends/graphics/openglsdl/openglsdl-graphics.h
@@ -0,0 +1,115 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef BACKENDS_GRAPHICS_OPENGLSDL_OPENGLSDL_GRAPHICS_H
+#define BACKENDS_GRAPHICS_OPENGLSDL_OPENGLSDL_GRAPHICS_H
+
+#include "backends/graphics/opengl/opengl-graphics.h"
+#include "backends/graphics/sdl/sdl-graphics.h"
+#include "backends/platform/sdl/sdl-sys.h"
+
+#include "common/array.h"
+#include "common/events.h"
+
+class OpenGLSdlGraphicsManager : public OpenGL::OpenGLGraphicsManager, public SdlGraphicsManager, public Common::EventObserver {
+public:
+	OpenGLSdlGraphicsManager(uint desktopWidth, uint desktopHeight, SdlEventSource *eventSource);
+	virtual ~OpenGLSdlGraphicsManager();
+
+	void initEventObserver();
+
+	// GraphicsManager API
+	virtual bool hasFeature(OSystem::Feature f);
+	virtual void setFeatureState(OSystem::Feature f, bool enable);
+	virtual bool getFeatureState(OSystem::Feature f);
+
+	virtual bool setGraphicsMode(int mode);
+	virtual void resetGraphicsScale();
+
+#ifdef USE_RGB_COLOR
+	virtual Common::List<Graphics::PixelFormat> getSupportedFormats() const;
+#endif
+
+	virtual void updateScreen();
+
+	// EventObserver API
+	virtual bool notifyEvent(const Common::Event &event);
+
+	// SdlGraphicsManager API
+	virtual void notifyVideoExpose();
+	virtual void notifyResize(const uint width, const uint height);
+	virtual void transformMouseCoordinates(Common::Point &point);
+	virtual void notifyMousePos(Common::Point mouse);
+
+protected:
+	virtual void setInternalMousePosition(int x, int y);
+
+	virtual bool loadVideoMode(uint requestedWidth, uint requestedHeight, const Graphics::PixelFormat &format);
+private:
+	bool setupMode(uint width, uint height);
+
+	uint32 _lastVideoModeLoad;
+	SDL_Surface *_hwScreen;
+
+	uint _lastRequestedWidth;
+	uint _lastRequestedHeight;
+	uint _graphicsScale;
+	bool _ignoreLoadVideoMode;
+	bool _gotResize;
+
+	bool _wantsFullScreen;
+	uint _ignoreResizeEvents;
+
+	struct VideoMode {
+		VideoMode() : width(0), height(0) {}
+		VideoMode(uint w, uint h) : width(w), height(h) {}
+
+		bool operator<(const VideoMode &right) const {
+			if (width < right.width) {
+				return true;
+			} else if (width == right.width && height < right.height) {
+				return true;
+			} else {
+				return false;
+			}
+		}
+
+		bool operator==(const VideoMode &right) const {
+			return width == right.width && height == right.height;
+		}
+
+		bool operator!=(const VideoMode &right) const {
+			return !(*this == right);
+		}
+
+		uint width, height;
+	};
+	typedef Common::Array<VideoMode> VideoModeArray;
+	VideoModeArray _fullscreenVideoModes;
+
+	uint _desiredFullscreenWidth;
+	uint _desiredFullscreenHeight;
+
+	virtual bool isHotkey(const Common::Event &event);
+};
+
+#endif
diff --git a/backends/module.mk b/backends/module.mk
index b66b0b04ec..1222d9a363 100644
--- a/backends/module.mk
+++ b/backends/module.mk
@@ -77,6 +77,11 @@ ifndef USE_SDL13
 MODULE_OBJS += \
 	audiocd/sdl/sdl-audiocd.o
 endif
+
+ifdef USE_OPENGL
+MODULE_OBJS += \
+	graphics/openglsdl/openglsdl-graphics.o
+endif
 endif
 
 ifdef POSIX
diff --git a/backends/platform/sdl/sdl.cpp b/backends/platform/sdl/sdl.cpp
index 16fe88e990..1431e1fc5e 100644
--- a/backends/platform/sdl/sdl.cpp
+++ b/backends/platform/sdl/sdl.cpp
@@ -47,6 +47,10 @@
 #include "backends/mutex/sdl/sdl-mutex.h"
 #include "backends/timer/sdl/sdl-timer.h"
 #include "backends/graphics/surfacesdl/surfacesdl-graphics.h"
+#ifdef USE_OPENGL
+#include "backends/graphics/openglsdl/openglsdl-graphics.h"
+#include "graphics/cursorman.h"
+#endif
 
 #include "icons/scummvm.xpm"
 
@@ -60,6 +64,14 @@
 
 OSystem_SDL::OSystem_SDL()
 	:
+#ifdef USE_OPENGL
+	_desktopWidth(0),
+	_desktopHeight(0),
+	_graphicsModes(0),
+	_graphicsMode(0),
+	_sdlModesCount(0),
+	_glModesCount(0),
+#endif
 	_inited(false),
 	_initedSDL(false),
 	_logger(0),
@@ -100,6 +112,10 @@ OSystem_SDL::~OSystem_SDL() {
 	delete _mutexManager;
 	_mutexManager = 0;
 
+#ifdef USE_OPENGL
+	delete[] _graphicsModes;
+#endif
+
 	delete _logger;
 	_logger = 0;
 
@@ -129,6 +145,11 @@ void OSystem_SDL::init() {
 	if (_taskbarManager == 0)
 		_taskbarManager = new Common::TaskbarManager();
 #endif
+
+#ifdef USE_OPENGL
+	// Setup a list with both SDL and OpenGL graphics modes
+	setupGraphicsModes();
+#endif
 }
 
 void OSystem_SDL::initBackend() {
@@ -140,8 +161,46 @@ void OSystem_SDL::initBackend() {
 	if (_eventSource == 0)
 		_eventSource = new SdlEventSource();
 
+	int graphicsManagerType = 0;
+
+#ifdef USE_OPENGL
+	// Query the desktop resolution. We simply hope nothing tried to change
+	// the resolution so far.
+	const SDL_VideoInfo *videoInfo = SDL_GetVideoInfo();
+	if (videoInfo && videoInfo->current_w > 0 && videoInfo->current_h > 0) {
+		_desktopWidth  = videoInfo->current_w;
+		_desktopHeight = videoInfo->current_h;
+	}
+#endif
+
 	if (_graphicsManager == 0) {
-		_graphicsManager = new SurfaceSdlGraphicsManager(_eventSource);
+#ifdef USE_OPENGL
+		if (ConfMan.hasKey("gfx_mode")) {
+			Common::String gfxMode(ConfMan.get("gfx_mode"));
+			bool use_opengl = false;
+			const OSystem::GraphicsMode *mode = OpenGLSdlGraphicsManager::supportedGraphicsModes();
+			int i = 0;
+			while (mode->name) {
+				if (scumm_stricmp(mode->name, gfxMode.c_str()) == 0) {
+					_graphicsMode = i + _sdlModesCount;
+					use_opengl = true;
+				}
+
+				mode++;
+				++i;
+			}
+
+			// If the gfx_mode is from OpenGL, create the OpenGL graphics manager
+			if (use_opengl) {
+				_graphicsManager = new OpenGLSdlGraphicsManager(_desktopWidth, _desktopHeight, _eventSource);
+				graphicsManagerType = 1;
+			}
+		}
+#endif
+		if (_graphicsManager == 0) {
+			_graphicsManager = new SurfaceSdlGraphicsManager(_eventSource);
+			graphicsManagerType = 0;
+		}
 	}
 
 	if (_savefileManager == 0)
@@ -183,7 +242,13 @@ void OSystem_SDL::initBackend() {
 	// so the virtual keyboard can be initialized, but we have to add the
 	// graphics manager as an event observer after initializing the event
 	// manager.
-	((SurfaceSdlGraphicsManager *)_graphicsManager)->initEventObserver();
+	if (graphicsManagerType == 0)
+		((SurfaceSdlGraphicsManager *)_graphicsManager)->initEventObserver();
+#ifdef USE_OPENGL
+	else if (graphicsManagerType == 1)
+		((OpenGLSdlGraphicsManager *)_graphicsManager)->initEventObserver();
+#endif
+
 }
 
 #if defined(USE_TASKBAR)
@@ -208,8 +273,9 @@ void OSystem_SDL::initSDL() {
 		if (ConfMan.hasKey("disable_sdl_parachute"))
 			sdlFlags |= SDL_INIT_NOPARACHUTE;
 
-#ifdef WEBOS
-		// WebOS needs this flag or otherwise the application won't start
+#if defined(WEBOS) || defined(USE_OPENGL)
+		// WebOS needs this flag or otherwise the application won't start.
+		// OpenGL SDL needs this to query the desktop resolution on startup.
 		sdlFlags |= SDL_INIT_VIDEO;
 #endif
 
@@ -478,3 +544,160 @@ Common::TimerManager *OSystem_SDL::getTimerManager() {
 	return _timerManager;
 #endif
 }
+
+#ifdef USE_OPENGL
+
+const OSystem::GraphicsMode *OSystem_SDL::getSupportedGraphicsModes() const {
+	return _graphicsModes;
+}
+
+int OSystem_SDL::getDefaultGraphicsMode() const {
+	// Return the default graphics mode from the current graphics manager
+	if (_graphicsMode < _sdlModesCount)
+		return _graphicsManager->getDefaultGraphicsMode();
+	else
+		return _graphicsManager->getDefaultGraphicsMode() + _sdlModesCount;
+}
+
+bool OSystem_SDL::setGraphicsMode(int mode) {
+	const OSystem::GraphicsMode *srcMode;
+	int i;
+
+	// Check if mode is from SDL or OpenGL
+	if (mode < _sdlModesCount) {
+		srcMode = SurfaceSdlGraphicsManager::supportedGraphicsModes();
+		i = 0;
+	} else {
+		srcMode = OpenGLSdlGraphicsManager::supportedGraphicsModes();
+		i = _sdlModesCount;
+	}
+
+	// Very hacky way to set up the old graphics manager state, in case we
+	// switch from SDL->OpenGL or OpenGL->SDL.
+	//
+	// This is a probably temporary workaround to fix bugs like #3368143
+	// "SDL/OpenGL: Crash when switching renderer backend".
+	const int screenWidth = _graphicsManager->getWidth();
+	const int screenHeight = _graphicsManager->getHeight();
+	const bool arState = _graphicsManager->getFeatureState(kFeatureAspectRatioCorrection);
+	const bool fullscreen = _graphicsManager->getFeatureState(kFeatureFullscreenMode);
+	const bool cursorPalette = _graphicsManager->getFeatureState(kFeatureCursorPalette);
+#ifdef USE_RGB_COLOR
+	const Graphics::PixelFormat pixelFormat = _graphicsManager->getScreenFormat();
+#endif
+
+	bool switchedManager = false;
+
+	// Loop through modes
+	while (srcMode->name) {
+		if (i == mode) {
+			// If the new mode and the current mode are not from the same graphics
+			// manager, delete and create the new mode graphics manager
+			if (_graphicsMode >= _sdlModesCount && mode < _sdlModesCount) {
+				debug(1, "switching to plain SDL graphics");
+				delete _graphicsManager;
+				_graphicsManager = new SurfaceSdlGraphicsManager(_eventSource);
+				((SurfaceSdlGraphicsManager *)_graphicsManager)->initEventObserver();
+				_graphicsManager->beginGFXTransaction();
+
+				switchedManager = true;
+			} else if (_graphicsMode < _sdlModesCount && mode >= _sdlModesCount) {
+				debug(1, "switching to OpenGL graphics");
+				delete _graphicsManager;
+				_graphicsManager = new OpenGLSdlGraphicsManager(_desktopWidth, _desktopHeight, _eventSource);
+				((OpenGLSdlGraphicsManager *)_graphicsManager)->initEventObserver();
+				_graphicsManager->beginGFXTransaction();
+
+				switchedManager = true;
+			}
+
+			_graphicsMode = mode;
+
+			if (switchedManager) {
+#ifdef USE_RGB_COLOR
+				_graphicsManager->initSize(screenWidth, screenHeight, &pixelFormat);
+#else
+				_graphicsManager->initSize(screenWidth, screenHeight, 0);
+#endif
+				_graphicsManager->setFeatureState(kFeatureAspectRatioCorrection, arState);
+				_graphicsManager->setFeatureState(kFeatureFullscreenMode, fullscreen);
+				_graphicsManager->setFeatureState(kFeatureCursorPalette, cursorPalette);
+
+				// Worst part about this right now, tell the cursor manager to
+				// resetup the cursor + cursor palette if necessarily
+
+				// First we need to try to setup the old state on the new manager...
+				if (_graphicsManager->endGFXTransaction() != kTransactionSuccess) {
+					// Oh my god if this failed the client code might just explode.
+					return false;
+				}
+
+				// Next setup the cursor again
+				CursorMan.pushCursor(0, 0, 0, 0, 0, 0);
+				CursorMan.popCursor();
+
+				// Next setup cursor palette if needed
+				if (cursorPalette) {
+					CursorMan.pushCursorPalette(0, 0, 0);
+					CursorMan.popCursorPalette();
+				}
+
+				_graphicsManager->beginGFXTransaction();
+				// Oh my god if this failed the client code might just explode.
+				return _graphicsManager->setGraphicsMode(srcMode->id);
+			} else {
+				return _graphicsManager->setGraphicsMode(srcMode->id);
+			}
+		}
+
+		i++;
+		srcMode++;
+	}
+
+	return false;
+}
+
+int OSystem_SDL::getGraphicsMode() const {
+	return _graphicsMode;
+}
+
+void OSystem_SDL::setupGraphicsModes() {
+	const OSystem::GraphicsMode *sdlGraphicsModes = SurfaceSdlGraphicsManager::supportedGraphicsModes();
+	const OSystem::GraphicsMode *openglGraphicsModes = OpenGLSdlGraphicsManager::supportedGraphicsModes();
+	_sdlModesCount = 0;
+	_glModesCount = 0;
+
+	// Count the number of graphics modes
+	const OSystem::GraphicsMode *srcMode = sdlGraphicsModes;
+	while (srcMode->name) {
+		_sdlModesCount++;
+		srcMode++;
+	}
+	srcMode = openglGraphicsModes;
+	while (srcMode->name) {
+		_glModesCount++;
+		srcMode++;
+	}
+
+	// Allocate enough space for merged array of modes
+	_graphicsModes = new OSystem::GraphicsMode[_glModesCount  + _sdlModesCount + 1];
+
+	// Copy SDL graphics modes
+	memcpy((void *)_graphicsModes, sdlGraphicsModes, _sdlModesCount * sizeof(OSystem::GraphicsMode));
+
+	// Copy OpenGL graphics modes
+	memcpy((void *)(_graphicsModes + _sdlModesCount), openglGraphicsModes, _glModesCount  * sizeof(OSystem::GraphicsMode));
+
+	// Set a null mode at the end
+	memset((void *)(_graphicsModes + _sdlModesCount + _glModesCount), 0, sizeof(OSystem::GraphicsMode));
+
+	// Set new internal ids for all modes
+	int i = 0;
+	OSystem::GraphicsMode *mode = _graphicsModes;
+	while (mode->name) {
+		mode->id = i++;
+		mode++;
+	}
+}
+
+#endif
diff --git a/backends/platform/sdl/sdl.h b/backends/platform/sdl/sdl.h
index 0012e88c51..590354b699 100644
--- a/backends/platform/sdl/sdl.h
+++ b/backends/platform/sdl/sdl.h
@@ -104,6 +104,25 @@ protected:
 	// Logging
 	virtual Common::WriteStream *createLogFile() { return 0; }
 	Backends::Log::Log *_logger;
+
+#ifdef USE_OPENGL
+	int _desktopWidth, _desktopHeight;
+
+	OSystem::GraphicsMode *_graphicsModes;
+	int _graphicsMode;
+	int _sdlModesCount;
+	int _glModesCount;
+
+	/**
+	 * Creates the merged graphics modes list
+	 */
+	virtual void setupGraphicsModes();
+
+	virtual const OSystem::GraphicsMode *getSupportedGraphicsModes() const;
+	virtual int getDefaultGraphicsMode() const;
+	virtual bool setGraphicsMode(int mode);
+	virtual int getGraphicsMode() const;
+#endif
 };
 
 #endif