Add smooth nearest neighbor scaling

This commit implements smooth nearest neighbor scaling, this scaling method looks sharper than linear scaling and not deformed like NN scaling.

data/language/en-GB.txt

@@ -4467,6 +4467,7 @@ STR_6155    :Neither KDialog nor Zenity are installed. Please install one, or co
 STR_6156    :Name is reserved
 STR_6157    :Console
 STR_6158    :Failed to load this file...{NEWLINE}Incompatible RCTC version: {COMMA16}
+STR_6159    :Smooth Nearest Neighbor
 
 #############
 # Scenarios #

distribution/changelog.txt

@@ -18,6 +18,7 @@
 - Feature: [#6414] Raise maximum launch speed of the Corkscrew RC back to 96 km/h (for RCT1 parity).
 - Feature: [#6433] Turn 'unlock all prices' into a regular (non-cheat, persistent) option.
 - Feature: [#6530] Land rights tool no longer blocks when a tile is not for purchase.
+- Feature: [#6568] Add smooth nearest neighbor scaling.
 - Feature: Allow using object files from RCT Classic.
 - Feature: Title sequences now testable in-game.
 - Fix: [#816] In the map window, there are more peeps flickering than there are selected (original bug).

src/openrct2-ui/UiContext.cpp

@@ -497,6 +497,10 @@ public:
         {
             _scaleQuality = 0;
         }
+        if (_scaleQuality == 3)
+        {
+            _scaleQuality = 1;
+        }
         snprintf(scaleQualityBuffer, sizeof(scaleQualityBuffer), "%u", _scaleQuality);
         SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, scaleQualityBuffer);
 

src/openrct2-ui/drawing/engines/HardwareDisplayDrawingEngine.cpp

@@ -40,6 +40,7 @@ private:
     SDL_Window *        _window                     = nullptr;
     SDL_Renderer *      _sdlRenderer                = nullptr;
     SDL_Texture *       _screenTexture              = nullptr;
+    SDL_Texture *       _scaledScreenTexture        = nullptr;
     SDL_PixelFormat *   _screenTextureFormat        = nullptr;
     uint32              _paletteHWMapped[256]       = { 0 };
 #ifdef __ENABLE_LIGHTFX__
@@ -53,6 +54,8 @@ private:
     bool    _pausedBeforeOverlay    = false;
 
     std::vector<uint32> _dirtyVisualsTime;
+    
+    bool    smoothNN = false;
 
 public:
     explicit HardwareDisplayDrawingEngine(IUiContext * uiContext)
@@ -98,7 +101,40 @@ public:
             }
         }
 
-        _screenTexture = SDL_CreateTexture(_sdlRenderer, pixelFormat, SDL_TEXTUREACCESS_STREAMING, width, height);
+        sint32 scaleQuality = gConfigGeneral.scale_quality;
+        if (gConfigGeneral.use_nn_at_integer_scales &&
+            gConfigGeneral.window_scale == std::floor(gConfigGeneral.window_scale))
+        {
+            scaleQuality = 0;
+        }
+        if (scaleQuality == 3)
+        {
+            scaleQuality = 1;
+            smoothNN = true;
+        }
+        else
+        {
+            smoothNN = false;
+        }
+
+        if (smoothNN)
+        {
+            SDL_DestroyTexture(_scaledScreenTexture);
+
+            char scaleQualityBuffer[4];
+            snprintf(scaleQualityBuffer, sizeof(scaleQualityBuffer), "%u", scaleQuality);
+            SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0");
+            _screenTexture = SDL_CreateTexture(_sdlRenderer, pixelFormat, SDL_TEXTUREACCESS_STREAMING, width, height);
+            SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, scaleQualityBuffer);
+
+            uint32 scale = std::ceil(gConfigGeneral.window_scale);
+            _scaledScreenTexture = SDL_CreateTexture(_sdlRenderer, pixelFormat, SDL_TEXTUREACCESS_TARGET,
+                                                     width * scale, height * scale);
+        }
+        else
+        {
+            _screenTexture = SDL_CreateTexture(_sdlRenderer, pixelFormat, SDL_TEXTUREACCESS_STREAMING,width, height);
+        }        
 
         uint32 format;
         SDL_QueryTexture(_screenTexture, &format, 0, 0, 0);
@@ -175,7 +211,18 @@ private:
         {
             CopyBitsToTexture(_screenTexture, _bits, (sint32)_width, (sint32)_height, _paletteHWMapped);
         }
-        SDL_RenderCopy(_sdlRenderer, _screenTexture, nullptr, nullptr);
+        if (smoothNN)
+        {
+            SDL_SetRenderTarget(_sdlRenderer, _scaledScreenTexture);
+            SDL_RenderCopy(_sdlRenderer, _screenTexture, nullptr, nullptr);
+            
+            SDL_SetRenderTarget(_sdlRenderer, nullptr);
+            SDL_RenderCopy(_sdlRenderer, _scaledScreenTexture, nullptr, nullptr);
+        }
+        else
+        {
+            SDL_RenderCopy(_sdlRenderer, _screenTexture, nullptr, nullptr);
+        }
 
         if (gShowDirtyVisuals)
         {

src/openrct2-ui/windows/Options.cpp

@@ -385,6 +385,7 @@ static const rct_string_id window_options_scale_quality_names[] = {
     STR_SCALING_QUALITY_NN,
     STR_SCALING_QUALITY_LINEAR,
     STR_SCALING_QUALITY_ANISOTROPIC,
+    STR_SCALING_QUALITY_SMOOTH_NN
 };
 
 static const rct_string_id window_options_fullscreen_mode_names[] = {
@@ -1022,11 +1023,13 @@ static void window_options_mousedown(rct_window *w, rct_widgetindex widgetIndex,
             gDropdownItemsFormat[0] = STR_DROPDOWN_MENU_LABEL;
             gDropdownItemsFormat[1] = STR_DROPDOWN_MENU_LABEL;
             gDropdownItemsFormat[2] = STR_DROPDOWN_MENU_LABEL;
+            gDropdownItemsFormat[3] = STR_DROPDOWN_MENU_LABEL;
             gDropdownItemsArgs[0] = STR_SCALING_QUALITY_NN;
             gDropdownItemsArgs[1] = STR_SCALING_QUALITY_LINEAR;
             gDropdownItemsArgs[2] = STR_SCALING_QUALITY_ANISOTROPIC;
+            gDropdownItemsArgs[3] = STR_SCALING_QUALITY_SMOOTH_NN;
 
-            window_options_show_dropdown(w, widget, 3);
+            window_options_show_dropdown(w, widget, 4);
 
             dropdown_set_checked(gConfigGeneral.scale_quality, true);
             break;

src/openrct2/localisation/string_ids.h

@@ -3814,6 +3814,8 @@ enum {
     STR_CONSOLE = 6157,
 
     STR_FAILED_TO_LOAD_IMCOMPATIBLE_RCTC_FLAG = 6158,
+    
+    STR_SCALING_QUALITY_SMOOTH_NN = 6159,
 
     // Have to include resource strings (from scenarios and objects) for the time being now that language is partially working
     STR_COUNT = 32768