Allow switching between OpenGL and other renderers without restarting

src/openrct2-ui/UiContext.cpp

@@ -516,44 +516,28 @@ public:
         sint32 x = SDL_WINDOWPOS_UNDEFINED_DISPLAY(defaultDisplay);
         sint32 y = SDL_WINDOWPOS_UNDEFINED_DISPLAY(defaultDisplay);
 
-        // Get saved window size
+        CreateWindow(x, y);
-        sint32 width = gConfigGeneral.window_width;
-        sint32 height = gConfigGeneral.window_height;
-        if (width <= 0) width = 640;
-        if (height <= 0) height = 480;
-
-        // Create window in window first rather than fullscreen so we have the display the window is on first
-        uint32 flags = SDL_WINDOW_RESIZABLE;
-        if (gConfigGeneral.drawing_engine == DRAWING_ENGINE_OPENGL)
-        {
-            flags |= SDL_WINDOW_OPENGL;
-        }
-
-        _window = SDL_CreateWindow(OPENRCT2_NAME, x, y, width, height, flags);
-        if (_window == nullptr)
-        {
-            SDLException::Throw("SDL_CreateWindow(...)");
-        }
-
-        SDL_SetWindowMinimumSize(_window, 720, 480);
-        SetCursorTrap(gConfigGeneral.trap_cursor);
-        _platformUiContext->SetWindowIcon(_window);
-
-        // Initialise the surface, palette and draw buffer
-        OnResize(width, height);
-
-        UpdateFullscreenResolutions();
-        SetFullscreenMode((FULLSCREEN_MODE)gConfigGeneral.fullscreen_mode);
 
         // Check if steam overlay renderer is loaded into the process
         _steamOverlayActive = _platformUiContext->IsSteamOverlayAttached();
-        TriggerResize();
     }
 
     void CloseWindow() override
     {
         drawing_engine_dispose();
         SDL_DestroyWindow(_window);
+        _window = nullptr;
+    }
+
+    void RecreateWindow() override
+    {
+        // Use the position of the current window for the new window
+        sint32 x, y;
+        SDL_SetWindowFullscreen(_window, 0);
+        SDL_GetWindowPosition(_window, &x, &y);
+
+        CloseWindow();
+        CreateWindow(x, y);
     }
 
     void ShowMessageBox(const std::string &message) override
@@ -646,6 +630,41 @@ public:
 
 
 private:
+    void CreateWindow(sint32 x, sint32 y)
+    {
+        // Get saved window size
+        sint32 width = gConfigGeneral.window_width;
+        sint32 height = gConfigGeneral.window_height;
+        if (width <= 0) width = 640;
+        if (height <= 0) height = 480;
+
+        // Create window in window first rather than fullscreen so we have the display the window is on first
+        uint32 flags = SDL_WINDOW_RESIZABLE;
+        if (gConfigGeneral.drawing_engine == DRAWING_ENGINE_OPENGL)
+        {
+            flags |= SDL_WINDOW_OPENGL;
+        }
+
+        _window = SDL_CreateWindow(OPENRCT2_NAME, x, y, width, height, flags);
+        if (_window == nullptr)
+        {
+            SDLException::Throw("SDL_CreateWindow(...)");
+        }
+
+        SDL_SetWindowMinimumSize(_window, 720, 480);
+        SetCursorTrap(gConfigGeneral.trap_cursor);
+        _platformUiContext->SetWindowIcon(_window);
+
+        // Initialise the surface, palette and draw buffer
+        drawing_engine_init();
+        OnResize(width, height);
+
+        UpdateFullscreenResolutions();
+        SetFullscreenMode((FULLSCREEN_MODE)gConfigGeneral.fullscreen_mode);
+
+        TriggerResize();
+    }
+
     void OnResize(sint32 width, sint32 height)
     {
         // Scale the native window size to the game's canvas size

src/openrct2-ui/drawing/engines/opengl/OpenGLAPI.cpp

@@ -121,8 +121,14 @@ static const char * TryLoadAllProcAddresses()
 
 namespace OpenGLState
 {
-    uint16 ActiveTexture = UINT16_MAX;
+    uint16 ActiveTexture;
-    GLuint CurrentProgram = UINT32_MAX;
+    GLuint CurrentProgram;
+
+    void Reset()
+    {
+        ActiveTexture = UINT16_MAX;
+        CurrentProgram = UINT32_MAX;
+    }
 }
 
 void OpenGLAPI::SetTexture(uint16 index, GLenum type, GLuint texture)
@@ -136,6 +142,8 @@ void OpenGLAPI::SetTexture(uint16 index, GLenum type, GLuint texture)
 
 bool OpenGLAPI::Initialise()
 {
+    OpenGLState::Reset();
+
 #ifdef OPENGL_NO_LINK
     const char * failedProcName = TryLoadAllProcAddresses();
     if (failedProcName != nullptr)

src/openrct2-ui/drawing/engines/opengl/OpenGLAPI.h

@@ -198,4 +198,6 @@ namespace OpenGLState
 {
     extern uint16 ActiveTexture;
     extern GLuint CurrentProgram;
+
+    void Reset();
 }

src/openrct2/Context.cpp

@@ -663,6 +663,11 @@ extern "C"
         return GetContext()->GetUiContext()->SetFullscreenMode((FULLSCREEN_MODE)mode);
     }
 
+    void context_recreate_window()
+    {
+        GetContext()->GetUiContext()->RecreateWindow();
+    }
+
     sint32 context_get_resolutions(Resolution * * outResolutions)
     {
         auto resolutions = GetContext()->GetUiContext()->GetFullscreenResolutions();

src/openrct2/Context.h

@@ -127,6 +127,7 @@ extern "C"
     bool context_is_input_active();
     void context_trigger_resize();
     void context_set_fullscreen_mode(sint32 mode);
+    void context_recreate_window();
     sint32 context_get_resolutions(struct Resolution * * outResolutions);
     sint32 context_get_width();
     sint32 context_get_height();

src/openrct2/drawing/NewDrawing.cpp

@@ -57,20 +57,18 @@ extern "C"
         return _drawingEngineType;
     }
 
-    bool drawing_engine_requires_restart(sint32 srcEngine, sint32 dstEngine)
+    bool drawing_engine_requires_new_window(sint32 srcEngine, sint32 dstEngine)
     {
-        // Linux requires a restart. This could be improved in the future by recreating the window,
-        // https://github.com/OpenRCT2/OpenRCT2/issues/2015
-        bool requiresRestart = true;
 #ifdef _WIN32
-        if (dstEngine != DRAWING_ENGINE_OPENGL)
+        if (srcEngine != DRAWING_ENGINE_OPENGL && dstEngine != DRAWING_ENGINE_OPENGL)
         {
             // Windows is apparently able to switch to hardware rendering on the fly although
             // using the same window in an unaccelerated and accelerated context is unsupported by SDL2
-            requiresRestart = false;
+            return false;
         }
 #endif
-        return requiresRestart;
+
+        return true;
     }
 
     void drawing_engine_init()
@@ -135,14 +133,12 @@ extern "C"
 
     void drawing_engine_resize()
     {
-        if (_drawingEngine == nullptr)
+        if (_drawingEngine != nullptr)
         {
-            drawing_engine_init();
-        }
-
             IUiContext * uiContext = GetContext()->GetUiContext();
             _drawingEngine->Resize(uiContext->GetWidth(), uiContext->GetHeight());
         }
+    }
 
     void drawing_engine_set_palette(const rct_palette_entry * colours)
     {

src/openrct2/drawing/NewDrawing.h

@@ -27,7 +27,7 @@ extern "C"
 extern rct_string_id DrawingEngineStringIds[3];
 
 sint32 drawing_engine_get_type();
-bool drawing_engine_requires_restart(sint32 srcEngine, sint32 dstEngine);
+bool drawing_engine_requires_new_window(sint32 srcEngine, sint32 dstEngine);
 void drawing_engine_init();
 void drawing_engine_resize();
 void drawing_engine_set_palette(const rct_palette_entry * colours);

src/openrct2/platform/platform.h

@@ -86,7 +86,7 @@ void platform_draw_require_end();
 void platform_free();
 void platform_update_palette(const uint8 *colours, sint32 start_index, sint32 num_colours);
 void platform_toggle_windowed_mode();
-void platform_refresh_video();
+void platform_refresh_video(bool recreate_window);
 void platform_get_date_utc(rct2_date *out_date);
 void platform_get_time_utc(rct2_time *out_time);
 void platform_get_date_local(rct2_date *out_date);

src/openrct2/platform/shared.c

@@ -152,11 +152,19 @@ void platform_toggle_windowed_mode()
     config_save_default();
 }
 
-void platform_refresh_video()
+void platform_refresh_video(bool recreate_window)
 {
+    if (recreate_window)
+    {
+        context_recreate_window();
+    }
+    else
+    {
         drawing_engine_dispose();
         drawing_engine_init();
         drawing_engine_resize();
+    }
+
     drawing_engine_set_palette(gPalette);
     gfx_invalidate_screen();
 }

src/openrct2/ui/DummyUiContext.cpp

@@ -33,6 +33,7 @@ namespace OpenRCT2 { namespace Ui
     public:
         void CreateWindow() override { }
         void CloseWindow() override { }
+        void RecreateWindow() override { }
         void * GetWindow() override { return nullptr; }
         sint32 GetWidth() override { return 0; }
         sint32 GetHeight() override { return 0; }

src/openrct2/ui/UiContext.h

@@ -94,6 +94,7 @@ namespace OpenRCT2
             // Window
             virtual void    CreateWindow() abstract;
             virtual void    CloseWindow() abstract;
+            virtual void    RecreateWindow() abstract;
             virtual void *  GetWindow() abstract;
             virtual sint32  GetWidth() abstract;
             virtual sint32  GetHeight() abstract;

src/openrct2/windows/options.c

@@ -639,7 +639,7 @@ static void window_options_mouseup(rct_window *w, rct_widgetindex widgetIndex)
             break;
         case WIDX_MINIMIZE_FOCUS_LOSS:
             gConfigGeneral.minimize_fullscreen_focus_loss ^= 1;
-            platform_refresh_video();
+            platform_refresh_video(false);
             config_save_default();
             window_invalidate(w);
             break;
@@ -1308,11 +1308,8 @@ static void window_options_dropdown(rct_window *w, rct_widgetindex widgetIndex,
                 sint32 dstEngine = dropdownIndex;
 
                 gConfigGeneral.drawing_engine = (uint8)dstEngine;
-                if (drawing_engine_requires_restart(srcEngine, dstEngine)) {
+                bool recreate_window = drawing_engine_requires_new_window(srcEngine, dstEngine);
-                    window_error_open(STR_RESTART_REQUIRED, STR_NONE);
+                platform_refresh_video(recreate_window);
-                } else {
-                    platform_refresh_video();
-                }
                 config_save_default();
                 window_invalidate(w);
             }