feat: Implement fizzle fade transition effects for menus and intros, enhancing visual transitions

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_dart/lib/src/menu/menu_manager.dart

@@ -13,6 +13,10 @@ enum WolfMenuScreen {
 
 enum WolfIntroSlide { retailWarning, pg13, title }
 
+enum WolfTransitionEffect { none, normalFade, fizzleFade }
+
+enum WolfTransitionPhase { idle, covering, revealing }
+
 enum _WolfIntroPhase { fadeIn, hold, fadeOut }
 
 enum WolfMenuMainAction {
@@ -102,9 +106,11 @@ class MenuManager {
 
   WolfMenuScreen _activeMenu = WolfMenuScreen.difficultySelect;
   WolfMenuScreen? _transitionTarget;
+  WolfTransitionEffect _transitionEffect = WolfTransitionEffect.normalFade;
   int _transitionElapsedMs = 0;
   bool _transitionSwappedMenu = false;
   WolfMenuScreen _introLandingMenu = WolfMenuScreen.mainMenu;
+  WolfTransitionEffect _introEffect = WolfTransitionEffect.normalFade;
   int _introSlideIndex = 0;
   int _introElapsedMs = 0;
   _WolfIntroPhase _introPhase = _WolfIntroPhase.fadeIn;
@@ -182,6 +188,34 @@ class MenuManager {
     }
   }
 
+  WolfTransitionEffect get introOverlayEffect {
+    if (!isIntroSplashActive || _introPhase == _WolfIntroPhase.hold) {
+      return WolfTransitionEffect.none;
+    }
+    return _introEffect;
+  }
+
+  WolfTransitionPhase get introOverlayPhase {
+    if (!isIntroSplashActive) {
+      return WolfTransitionPhase.idle;
+    }
+    switch (_introPhase) {
+      case _WolfIntroPhase.fadeIn:
+        return WolfTransitionPhase.revealing;
+      case _WolfIntroPhase.hold:
+        return WolfTransitionPhase.idle;
+      case _WolfIntroPhase.fadeOut:
+        return WolfTransitionPhase.covering;
+    }
+  }
+
+  double get introOverlayPhaseProgress {
+    if (!isIntroSplashActive || _introPhase == _WolfIntroPhase.hold) {
+      return 0.0;
+    }
+    return (_introElapsedMs / introFadeDurationMs).clamp(0.0, 1.0);
+  }
+
   /// Returns the fade alpha during transitions (0.0..1.0).
   double get transitionAlpha {
     if (!isTransitioning) {
@@ -195,6 +229,35 @@ class MenuManager {
     return (1.0 - (fadeInElapsed / half)).clamp(0.0, 1.0);
   }
 
+  WolfTransitionEffect get transitionEffect {
+    if (!isTransitioning) {
+      return WolfTransitionEffect.none;
+    }
+    return _transitionEffect;
+  }
+
+  WolfTransitionPhase get transitionPhase {
+    if (!isTransitioning) {
+      return WolfTransitionPhase.idle;
+    }
+    final int half = transitionDurationMs ~/ 2;
+    if (_transitionElapsedMs < half) {
+      return WolfTransitionPhase.covering;
+    }
+    return WolfTransitionPhase.revealing;
+  }
+
+  double get transitionPhaseProgress {
+    if (!isTransitioning) {
+      return 0.0;
+    }
+    final int half = transitionDurationMs ~/ 2;
+    if (_transitionElapsedMs < half) {
+      return (_transitionElapsedMs / half).clamp(0.0, 1.0);
+    }
+    return ((_transitionElapsedMs - half) / half).clamp(0.0, 1.0);
+  }
+
   int get selectedMainIndex => _selectedMainIndex;
 
   int get selectedGameIndex => _selectedGameIndex;
@@ -272,6 +335,7 @@ class MenuManager {
     Difficulty? initialDifficulty,
     bool hasResumableGame = false,
     bool initialGameIsRetail = false,
+    WolfTransitionEffect introEffect = WolfTransitionEffect.normalFade,
   }) {
     _gameCount = gameCount;
     _showResumeOption = hasResumableGame;
@@ -286,6 +350,7 @@ class MenuManager {
     _introLandingMenu = WolfMenuScreen.mainMenu;
     if (gameCount > 1) {
       _activeMenu = WolfMenuScreen.gameSelect;
+      _introEffect = introEffect;
       _introElapsedMs = 0;
       _introPhase = _WolfIntroPhase.fadeIn;
       _introSlideIndex = 0;
@@ -294,9 +359,13 @@ class MenuManager {
         WolfIntroSlide.title,
       ];
     } else {
-      _startIntroSequence(includeRetailWarning: initialGameIsRetail);
+      _startIntroSequence(
+        includeRetailWarning: initialGameIsRetail,
+        effect: introEffect,
+      );
     }
     _transitionTarget = null;
+    _transitionEffect = WolfTransitionEffect.normalFade;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
     _resetEdgeState();
@@ -306,12 +375,17 @@ class MenuManager {
   void beginIntroSplash({
     WolfMenuScreen landingMenu = WolfMenuScreen.mainMenu,
     bool includeRetailWarning = false,
+    WolfTransitionEffect effect = WolfTransitionEffect.normalFade,
   }) {
     _introLandingMenu = landingMenu;
     _transitionTarget = null;
+    _transitionEffect = WolfTransitionEffect.normalFade;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
-    _startIntroSequence(includeRetailWarning: includeRetailWarning);
+    _startIntroSequence(
+      includeRetailWarning: includeRetailWarning,
+      effect: effect,
+    );
     _resetEdgeState();
   }
 
@@ -336,8 +410,10 @@ class MenuManager {
     }
     _activeMenu = WolfMenuScreen.mainMenu;
     _transitionTarget = null;
+    _transitionEffect = WolfTransitionEffect.normalFade;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
+    _introEffect = WolfTransitionEffect.normalFade;
     _introElapsedMs = 0;
     _resetEdgeState();
   }
@@ -449,6 +525,7 @@ class MenuManager {
             _isSelectableChangeViewIndex,
           );
     _transitionTarget = null;
+    _transitionEffect = WolfTransitionEffect.normalFade;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
     _resetEdgeState();
@@ -464,6 +541,7 @@ class MenuManager {
             _isSelectableRendererOptionIndex,
           );
     _transitionTarget = null;
+    _transitionEffect = WolfTransitionEffect.normalFade;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
     _resetEdgeState();
@@ -473,11 +551,15 @@ class MenuManager {
   ///
   /// Hosts can reuse this fade timing for future pre-menu splash/image
   /// sequences so transitions feel consistent across the whole app.
-  void startTransition(WolfMenuScreen target) {
+  void startTransition(
+    WolfMenuScreen target, {
+    WolfTransitionEffect effect = WolfTransitionEffect.normalFade,
+  }) {
     if (_activeMenu == target) {
       return;
     }
     _transitionTarget = target;
+    _transitionEffect = effect;
     _transitionElapsedMs = 0;
     _transitionSwappedMenu = false;
     _resetEdgeState();
@@ -501,6 +583,7 @@ class MenuManager {
     }
     if (_transitionElapsedMs >= transitionDurationMs) {
       _transitionTarget = null;
+      _transitionEffect = WolfTransitionEffect.normalFade;
       _transitionElapsedMs = 0;
       _transitionSwappedMenu = false;
     }
@@ -527,8 +610,12 @@ class MenuManager {
     _consumeEdgeState(input);
   }
 
-  void _startIntroSequence({required bool includeRetailWarning}) {
+  void _startIntroSequence({
+    required bool includeRetailWarning,
+    required WolfTransitionEffect effect,
+  }) {
     _activeMenu = WolfMenuScreen.introSplash;
+    _introEffect = effect;
     _introSlides = includeRetailWarning
         ? <WolfIntroSlide>[
             WolfIntroSlide.retailWarning,

packages/wolf_3d_dart/lib/src/rendering/ascii_renderer.dart

@@ -3,6 +3,7 @@ import 'dart:math' as math;
 
 import 'package:arcane_helper_utils/arcane_helper_utils.dart';
 import 'package:wolf_3d_dart/src/menu/menu_manager.dart';
+import 'package:wolf_3d_dart/src/rendering/fizzle_fade.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 import 'package:wolf_3d_dart/wolf_3d_menu.dart';
@@ -130,6 +131,8 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
 
   late List<List<ColoredChar>> _screen;
   late List<List<int>> _scenePixels;
+  List<List<ColoredChar>> _screenScratch = const <List<ColoredChar>>[];
+  List<List<int>> _scenePixelsScratch = const <List<int>>[];
   List<int>? _mainMenuBandFirstColumn;
   String? _lastLoggedThemeName;
 
@@ -488,7 +491,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       }
 
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -538,7 +541,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       }
 
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -597,7 +600,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
           );
         }
         _drawCenteredMenuFooter();
-        _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+        _applyMenuTransition(engine.menuManager, bgColor);
         return;
       }
 
@@ -638,7 +641,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       }
 
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -742,7 +745,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       }
 
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -795,7 +798,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       }
 
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -851,7 +854,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
         );
       }
       _drawCenteredMenuFooter();
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -878,7 +881,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
     }
 
     _drawCenteredMenuFooter();
-    _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+    _applyMenuTransition(engine.menuManager, bgColor);
   }
 
   String _gameTitle(GameVersion version) {
@@ -932,10 +935,7 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
       _blitVgaImageAscii(image, x, y);
     }
 
-    _applyMenuFade(
+    _applyIntroTransition(engine.menuManager, _rgbToPaletteColor(0x000000));
-      engine.menuManager.introOverlayAlpha,
-      _rgbToPaletteColor(0x000000),
-    );
   }
 
   void _drawRetailWarningIntro(
@@ -1085,6 +1085,148 @@ class AsciiRenderer extends CliRendererBackend<dynamic> {
     }
   }
 
+  void _applyMenuTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.transitionEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.transitionAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.transitionPhase,
+          progress: menuManager.transitionPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
+  void _applyIntroTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.introOverlayEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.introOverlayAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.introOverlayPhase,
+          progress: menuManager.introOverlayPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
+  void _applyFizzleTransition({
+    required WolfTransitionPhase phase,
+    required double progress,
+    required int coverColor,
+  }) {
+    switch (phase) {
+      case WolfTransitionPhase.idle:
+        return;
+      case WolfTransitionPhase.covering:
+        _applyFizzleCover(progress, coverColor);
+        return;
+      case WolfTransitionPhase.revealing:
+        _applyFizzleReveal(progress, coverColor);
+        return;
+    }
+  }
+
+  void _applyFizzleCover(double progress, int coverColor) {
+    final int coverCount = FizzleFade.revealCountForProgress(progress);
+    if (coverCount <= 0) {
+      return;
+    }
+
+    FizzleFade.forEachCanonicalPixel(coverCount, (int x, int y) {
+      _fillRect320(x, y, 1, 1, coverColor);
+    });
+  }
+
+  void _applyFizzleReveal(double progress, int coverColor) {
+    final int revealCount = FizzleFade.revealCountForProgress(progress);
+    if (revealCount <= 0) {
+      if (_usesTerminalLayout) {
+        _fillTerminalRect(0, 0, width, _terminalPixelHeight, coverColor);
+      } else {
+        _fillRect(0, 0, width, height, ' ', coverColor);
+      }
+      return;
+    }
+    if (revealCount >= FizzleFade.canonicalPixelCount) {
+      return;
+    }
+
+    _captureTransitionScratch();
+    if (_usesTerminalLayout) {
+      _fillTerminalRect(0, 0, width, _terminalPixelHeight, coverColor);
+    } else {
+      _fillRect(0, 0, width, height, ' ', coverColor);
+    }
+
+    FizzleFade.forEachCanonicalPixel(revealCount, (int x, int y) {
+      _copyCanonicalPixelFromScratch(x, y);
+    });
+  }
+
+  void _captureTransitionScratch() {
+    if (_usesTerminalLayout) {
+      _scenePixelsScratch = List<List<int>>.generate(
+        _scenePixels.length,
+        (int y) => List<int>.from(_scenePixels[y]),
+      );
+      return;
+    }
+
+    _screenScratch = List<List<ColoredChar>>.generate(
+      _screen.length,
+      (int y) => List<ColoredChar>.from(_screen[y]),
+    );
+  }
+
+  void _copyCanonicalPixelFromScratch(int x320, int y200) {
+    final double scaleX =
+        (_usesTerminalLayout ? projectionWidth : width) / 320.0;
+    final double scaleY =
+        (_usesTerminalLayout ? _terminalPixelHeight : height) / 200.0;
+    final int offsetX = _usesTerminalLayout ? projectionOffsetX : 0;
+    final int startX = offsetX + (x320 * scaleX).floor();
+    final int endX = offsetX + ((x320 + 1) * scaleX).ceil();
+    final int startY = (y200 * scaleY).floor();
+    final int endY = ((y200 + 1) * scaleY).ceil();
+
+    if (_usesTerminalLayout) {
+      for (int y = startY; y < endY; y++) {
+        if (y < 0 || y >= _terminalPixelHeight) {
+          continue;
+        }
+        for (int x = startX; x < endX; x++) {
+          if (x < 0 || x >= width) {
+            continue;
+          }
+          _scenePixels[y][x] = _scenePixelsScratch[y][x];
+        }
+      }
+      return;
+    }
+
+    for (int y = startY; y < endY; y++) {
+      if (y < 0 || y >= height) {
+        continue;
+      }
+      for (int x = startX; x < endX; x++) {
+        if (x < 0 || x >= width) {
+          continue;
+        }
+        _screen[y][x] = _screenScratch[y][x];
+      }
+    }
+  }
+
   void _applyMenuFade(double alpha, int fadeColor) {
     if (alpha <= 0.0) {
       return;

packages/wolf_3d_dart/lib/src/rendering/fizzle_fade.dart

@@ -0,0 +1,66 @@
+import 'dart:collection';
+
+/// Canonical Wolf3D-style 17-bit Galois LFSR used for Fizzle Fade ordering.
+///
+/// The sequence mirrors the original coordinate extraction strategy:
+/// low 8 bits minus one form `y`, the next 9 bits form `x`, and out-of-bounds
+/// points are skipped. For menu and intro rendering we use the original
+/// canonical 320x200 coordinate space and let renderers scale that to their
+/// output buffer.
+abstract final class FizzleFade {
+  static const int canonicalWidth = 320;
+  static const int canonicalHeight = 200;
+  static const int canonicalPixelCount = canonicalWidth * canonicalHeight;
+  static const int seed = 1;
+  static const int _xorMask = 0x12000;
+  static final List<int> _canonicalSequence = List<int>.unmodifiable(
+    _buildSequence(width: canonicalWidth, height: canonicalHeight),
+  );
+
+  static List<int> get canonicalSequence => _canonicalSequence;
+
+  static int nextState(int state) {
+    final bool lsbSet = (state & 1) != 0;
+    int next = state >> 1;
+    if (lsbSet) {
+      next ^= _xorMask;
+    }
+    return next;
+  }
+
+  static int xForState(int state) => (state >> 8) & 0x1FF;
+
+  static int yForState(int state) => ((state & 0xFF) - 1) & 0xFF;
+
+  static bool isInBounds(int state, {required int width, required int height}) {
+    return xForState(state) < width && yForState(state) < height;
+  }
+
+  static int revealCountForProgress(double progress, {int? pixelCount}) {
+    final int total = pixelCount ?? canonicalPixelCount;
+    return (progress.clamp(0.0, 1.0) * total).round().clamp(0, total);
+  }
+
+  static void forEachCanonicalPixel(
+    int count,
+    void Function(int x, int y) plot,
+  ) {
+    final int limit = count.clamp(0, canonicalPixelCount);
+    for (int i = 0; i < limit; i++) {
+      final int packed = _canonicalSequence[i];
+      plot(packed & 0xFFFF, packed >> 16);
+    }
+  }
+
+  static List<int> _buildSequence({required int width, required int height}) {
+    final List<int> points = <int>[];
+    int state = seed;
+    do {
+      if (isInBounds(state, width: width, height: height)) {
+        points.add((yForState(state) << 16) | xForState(state));
+      }
+      state = nextState(state);
+    } while (state != seed);
+    return UnmodifiableListView<int>(points);
+  }
+}

packages/wolf_3d_dart/lib/src/rendering/sixel_renderer.dart

@@ -8,6 +8,7 @@ import 'dart:typed_data';
 
 import 'package:wolf_3d_dart/src/input/cli_input.dart';
 import 'package:wolf_3d_dart/src/menu/menu_manager.dart';
+import 'package:wolf_3d_dart/src/rendering/fizzle_fade.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 import 'package:wolf_3d_dart/wolf_3d_menu.dart';
@@ -36,6 +37,7 @@ class SixelRenderer extends CliRendererBackend<String> {
   static const int _headerHeadingY = 24;
 
   late Uint8List _screen;
+  Uint8List _transitionScratch = Uint8List(0);
   List<int>? _mainMenuBandFirstColumn;
   int _offsetColumns = 0;
   int _offsetRows = 0;
@@ -435,7 +437,7 @@ class SixelRenderer extends CliRendererBackend<String> {
           scale: 1,
         );
       }
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -470,7 +472,7 @@ class SixelRenderer extends CliRendererBackend<String> {
           scale: 1,
         );
       }
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -522,7 +524,7 @@ class SixelRenderer extends CliRendererBackend<String> {
           );
         }
       }
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -615,7 +617,7 @@ class SixelRenderer extends CliRendererBackend<String> {
           scale: 1,
         );
       }
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -662,7 +664,7 @@ class SixelRenderer extends CliRendererBackend<String> {
           scale: 1,
         );
       }
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -676,7 +678,7 @@ class SixelRenderer extends CliRendererBackend<String> {
     _fillRect320(28, 70, 264, 82, panelColor);
     if (_useCompactMenuLayout) {
       _drawCompactMenu(selectedDifficultyIndex, headingIndex, panelColor);
-      _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+      _applyMenuTransition(engine.menuManager, bgColor);
       return;
     }
 
@@ -717,7 +719,7 @@ class SixelRenderer extends CliRendererBackend<String> {
       );
     }
 
-    _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+    _applyMenuTransition(engine.menuManager, bgColor);
   }
 
   void _drawCustomizeMenuHeader(
@@ -816,10 +818,7 @@ class SixelRenderer extends CliRendererBackend<String> {
       _blitVgaImage(image, x, y);
     }
 
-    _applyMenuFade(
+    _applyIntroTransition(engine.menuManager, _rgbToPaletteIndex(0x000000));
-      engine.menuManager.introOverlayAlpha,
-      _rgbToPaletteIndex(0x000000),
-    );
   }
 
   void _drawRetailWarningIntro(int backgroundColor) {
@@ -861,6 +860,117 @@ class SixelRenderer extends CliRendererBackend<String> {
     return bestIndex;
   }
 
+  void _applyMenuTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.transitionEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.transitionAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.transitionPhase,
+          progress: menuManager.transitionPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
+  void _applyIntroTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.introOverlayEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.introOverlayAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.introOverlayPhase,
+          progress: menuManager.introOverlayPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
+  void _applyFizzleTransition({
+    required WolfTransitionPhase phase,
+    required double progress,
+    required int coverColor,
+  }) {
+    switch (phase) {
+      case WolfTransitionPhase.idle:
+        return;
+      case WolfTransitionPhase.covering:
+        _applyFizzleCover(progress, coverColor);
+        return;
+      case WolfTransitionPhase.revealing:
+        _applyFizzleReveal(progress, coverColor);
+        return;
+    }
+  }
+
+  void _applyFizzleCover(double progress, int coverColor) {
+    final int coverCount = FizzleFade.revealCountForProgress(progress);
+    if (coverCount <= 0) {
+      return;
+    }
+
+    FizzleFade.forEachCanonicalPixel(coverCount, (int x, int y) {
+      _fillRect320(x, y, 1, 1, coverColor);
+    });
+  }
+
+  void _applyFizzleReveal(double progress, int coverColor) {
+    final int revealCount = FizzleFade.revealCountForProgress(progress);
+    if (revealCount <= 0) {
+      _screen.fillRange(0, _screen.length, coverColor);
+      return;
+    }
+    if (revealCount >= FizzleFade.canonicalPixelCount) {
+      return;
+    }
+
+    _ensureTransitionScratch();
+    _transitionScratch.setAll(0, _screen);
+    _screen.fillRange(0, _screen.length, coverColor);
+
+    FizzleFade.forEachCanonicalPixel(revealCount, (int x, int y) {
+      _copyCanonicalPixelFromScratch(x, y);
+    });
+  }
+
+  void _ensureTransitionScratch() {
+    if (_transitionScratch.length == _screen.length) {
+      return;
+    }
+    _transitionScratch = Uint8List(_screen.length);
+  }
+
+  void _copyCanonicalPixelFromScratch(int x320, int y200) {
+    final double scaleX = width / 320.0;
+    final double scaleY = height / 200.0;
+    final int startX = (x320 * scaleX).floor();
+    final int endX = ((x320 + 1) * scaleX).ceil();
+    final int startY = (y200 * scaleY).floor();
+    final int endY = ((y200 + 1) * scaleY).ceil();
+
+    for (int y = startY; y < endY; y++) {
+      if (y < 0 || y >= height) {
+        continue;
+      }
+      final int rowOffset = y * width;
+      for (int x = startX; x < endX; x++) {
+        if (x < 0 || x >= width) {
+          continue;
+        }
+        final int index = rowOffset + x;
+        _screen[index] = _transitionScratch[index];
+      }
+    }
+  }
+
   void _applyMenuFade(double alpha, int bgColor) {
     if (alpha <= 0.0) {
       return;

packages/wolf_3d_dart/lib/src/rendering/software_renderer.dart

@@ -1,6 +1,8 @@
 import 'dart:math' as math;
+import 'dart:typed_data';
 
 import 'package:wolf_3d_dart/src/menu/menu_manager.dart';
+import 'package:wolf_3d_dart/src/rendering/fizzle_fade.dart';
 import 'package:wolf_3d_dart/src/rendering/menu_font.dart';
 import 'package:wolf_3d_dart/src/rendering/renderer_backend.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
@@ -18,6 +20,7 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
   static const int _headerHeadingY = 24;
 
   late FrameBuffer _buffer;
+  Uint32List _transitionScratch = Uint32List(0);
   List<int>? _mainMenuBandFirstColumn;
 
   @override
@@ -233,7 +236,7 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
         break;
     }
 
-    _applyMenuFade(engine.menuManager.transitionAlpha, bgColor);
+    _applyMenuTransition(engine.menuManager, bgColor);
   }
 
   void _drawIntroSplash(WolfEngine engine, WolfClassicMenuArt art) {
@@ -275,10 +278,7 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
       }
     }
 
-    _applyMenuFade(
+    _applyIntroTransition(engine.menuManager, _rgbToFrameColor(0x000000));
-      engine.menuManager.introOverlayAlpha,
-      _rgbToFrameColor(0x000000),
-    );
   }
 
   void _drawRetailWarningIntro(int backgroundColor) {
@@ -550,7 +550,8 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
         ? 0
         : ((optionEntries.length - 1) * optionsRowStep) + 10;
     final int optionsRowStart =
-        optionsPanelY + ((optionsPanelH - optionsRowsHeight) ~/ 2).clamp(0, 200);
+        optionsPanelY +
+        ((optionsPanelH - optionsRowsHeight) ~/ 2).clamp(0, 200);
     for (int i = 0; i < optionEntries.length; i++) {
       final int optionIndex = modeCount + i;
       final bool isSelected = optionIndex == selectedIndex;
@@ -937,6 +938,40 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
     }
   }
 
+  void _applyMenuTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.transitionEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.transitionAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.transitionPhase,
+          progress: menuManager.transitionPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
+  void _applyIntroTransition(MenuManager menuManager, int coverColor) {
+    switch (menuManager.introOverlayEffect) {
+      case WolfTransitionEffect.none:
+        return;
+      case WolfTransitionEffect.normalFade:
+        _applyMenuFade(menuManager.introOverlayAlpha, coverColor);
+        return;
+      case WolfTransitionEffect.fizzleFade:
+        _applyFizzleTransition(
+          phase: menuManager.introOverlayPhase,
+          progress: menuManager.introOverlayPhaseProgress,
+          coverColor: coverColor,
+        );
+        return;
+    }
+  }
+
   void _applyMenuFade(double alpha, int fadeColor) {
     if (alpha <= 0.0) {
       return;
@@ -959,6 +994,81 @@ class SoftwareRenderer extends RendererBackend<FrameBuffer> {
     }
   }
 
+  void _applyFizzleTransition({
+    required WolfTransitionPhase phase,
+    required double progress,
+    required int coverColor,
+  }) {
+    switch (phase) {
+      case WolfTransitionPhase.idle:
+        return;
+      case WolfTransitionPhase.covering:
+        _applyFizzleCover(progress, coverColor);
+        return;
+      case WolfTransitionPhase.revealing:
+        _applyFizzleReveal(progress, coverColor);
+        return;
+    }
+  }
+
+  void _applyFizzleCover(double progress, int coverColor) {
+    final int coverCount = FizzleFade.revealCountForProgress(progress);
+    if (coverCount <= 0) {
+      return;
+    }
+
+    FizzleFade.forEachCanonicalPixel(coverCount, (int x, int y) {
+      _fillCanonicalRect(x, y, 1, 1, coverColor);
+    });
+  }
+
+  void _applyFizzleReveal(double progress, int coverColor) {
+    final int revealCount = FizzleFade.revealCountForProgress(progress);
+    if (revealCount <= 0) {
+      _buffer.pixels.fillRange(0, _buffer.pixels.length, coverColor);
+      return;
+    }
+    if (revealCount >= FizzleFade.canonicalPixelCount) {
+      return;
+    }
+
+    _ensureTransitionScratch();
+    _transitionScratch.setAll(0, _buffer.pixels);
+    _buffer.pixels.fillRange(0, _buffer.pixels.length, coverColor);
+
+    FizzleFade.forEachCanonicalPixel(revealCount, (int x, int y) {
+      _copyCanonicalPixelFromScratch(x, y);
+    });
+  }
+
+  void _ensureTransitionScratch() {
+    if (_transitionScratch.length == _buffer.pixels.length) {
+      return;
+    }
+    _transitionScratch = Uint32List(_buffer.pixels.length);
+  }
+
+  void _copyCanonicalPixelFromScratch(int startX320, int startY200) {
+    final int startX = (startX320 * _uiScaleX).floor();
+    final int endX = ((startX320 + 1) * _uiScaleX).ceil();
+    final int startY = (startY200 * _uiScaleY).floor();
+    final int endY = ((startY200 + 1) * _uiScaleY).ceil();
+
+    for (int y = startY; y < endY; y++) {
+      if (y < 0 || y >= height) {
+        continue;
+      }
+      final int rowStart = y * width;
+      for (int x = startX; x < endX; x++) {
+        if (x < 0 || x >= width) {
+          continue;
+        }
+        final int index = rowStart + x;
+        _buffer.pixels[index] = _transitionScratch[index];
+      }
+    }
+  }
+
   /// Converts an `RRGGBB` menu color into the framebuffer's packed channel
   /// order (`0xAABBGGRR`) used throughout this renderer.
   int _rgbToFrameColor(int rgb) {

packages/wolf_3d_dart/test/engine/level_state_and_pause_menu_test.dart

@@ -223,6 +223,46 @@ void main() {
       expect(manager.selectedMainIndex, 0);
     });
 
+    test('menu transition defaults to normal fade and can opt into fizzle', () {
+      final manager = MenuManager();
+
+      manager.showMainMenu(hasResumableGame: false);
+      manager.startTransition(WolfMenuScreen.difficultySelect);
+
+      expect(manager.transitionEffect, WolfTransitionEffect.normalFade);
+      expect(manager.transitionPhase, WolfTransitionPhase.covering);
+      expect(manager.transitionPhaseProgress, 0.0);
+      expect(manager.activeMenu, WolfMenuScreen.mainMenu);
+
+      manager.tickTransition(MenuManager.transitionDurationMs ~/ 4);
+      expect(manager.transitionPhase, WolfTransitionPhase.covering);
+      expect(manager.transitionPhaseProgress, closeTo(0.5, 0.001));
+      expect(manager.activeMenu, WolfMenuScreen.mainMenu);
+
+      manager.tickTransition(MenuManager.transitionDurationMs ~/ 4);
+      expect(manager.transitionPhase, WolfTransitionPhase.revealing);
+      expect(manager.transitionPhaseProgress, 0.0);
+      expect(manager.activeMenu, WolfMenuScreen.difficultySelect);
+
+      manager.tickTransition(MenuManager.transitionDurationMs ~/ 4);
+      expect(manager.transitionPhase, WolfTransitionPhase.revealing);
+      expect(manager.transitionPhaseProgress, closeTo(0.5, 0.001));
+
+      manager.tickTransition(MenuManager.transitionDurationMs ~/ 4);
+      expect(manager.isTransitioning, isFalse);
+      expect(manager.transitionEffect, WolfTransitionEffect.none);
+      expect(manager.transitionPhase, WolfTransitionPhase.idle);
+      expect(manager.transitionPhaseProgress, 0.0);
+
+      manager.startTransition(
+        WolfMenuScreen.mainMenu,
+        effect: WolfTransitionEffect.fizzleFade,
+      );
+
+      expect(manager.transitionEffect, WolfTransitionEffect.fizzleFade);
+      expect(manager.transitionPhase, WolfTransitionPhase.covering);
+    });
+
     test('quit selection triggers dedicated quit callback', () {
       final input = _TestInput();
       int quitCalls = 0;

packages/wolf_3d_dart/test/rendering/fizzle_fade_renderer_test.dart

@@ -0,0 +1,227 @@
+import 'dart:typed_data';
+
+import 'package:test/test.dart';
+import 'package:wolf_3d_dart/src/menu/menu_manager.dart';
+import 'package:wolf_3d_dart/src/rendering/fizzle_fade.dart';
+import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
+import 'package:wolf_3d_dart/wolf_3d_engine.dart';
+import 'package:wolf_3d_dart/wolf_3d_input.dart';
+import 'package:wolf_3d_dart/wolf_3d_renderer.dart';
+
+void main() {
+  group('Fizzle fade sequence', () {
+    test('covers every canonical menu pixel exactly once', () {
+      final sequence = FizzleFade.canonicalSequence;
+
+      expect(sequence.length, FizzleFade.canonicalPixelCount);
+      expect(sequence.toSet().length, FizzleFade.canonicalPixelCount);
+      expect(sequence.first, 0);
+      expect(FizzleFade.nextState(FizzleFade.seed), 0x12000);
+    });
+  });
+
+  group('Software renderer transitions', () {
+    test(
+      'default intro fade-in starts fully black and reveals by hold phase',
+      () {
+        final engine = _buildEngine(frameBuffer: FrameBuffer(320, 200));
+        final renderer = SoftwareRenderer();
+        final int black = _rgbToFrameColor(0x000000);
+
+        engine.init();
+
+        final FrameBuffer startFrame = renderer.render(engine);
+        expect(startFrame.pixels.every((pixel) => pixel == black), isTrue);
+
+        engine.menuManager.tickTransition(MenuManager.introFadeDurationMs);
+
+        final FrameBuffer revealedFrame = renderer.render(engine);
+        expect(revealedFrame.pixels.any((pixel) => pixel != black), isTrue);
+      },
+    );
+
+    test(
+      'fizzle menu transition covers at midpoint and reveals target menu on completion',
+      () {
+        final engine = _buildEngine(frameBuffer: FrameBuffer(320, 200));
+        final baselineEngine = _buildEngine(frameBuffer: FrameBuffer(320, 200));
+        final difficultyEngine = _buildEngine(
+          frameBuffer: FrameBuffer(320, 200),
+        );
+        final renderer = SoftwareRenderer();
+        final int bgColor = _rgbToFrameColor(
+          engine.menuManager.menuBackgroundRgb,
+        );
+
+        engine.init();
+        baselineEngine.init();
+        difficultyEngine.init();
+
+        engine.menuManager.showMainMenu(hasResumableGame: false);
+        baselineEngine.menuManager.showMainMenu(hasResumableGame: false);
+        difficultyEngine.menuManager.beginDifficultySelection();
+
+        final List<int> mainMenuFrame = List<int>.from(
+          renderer.render(baselineEngine).pixels,
+        );
+
+        engine.menuManager.startTransition(
+          WolfMenuScreen.difficultySelect,
+          effect: WolfTransitionEffect.fizzleFade,
+        );
+        engine.menuManager.tickTransition(
+          MenuManager.transitionDurationMs ~/ 4,
+        );
+        final List<int> partialFrame = List<int>.from(
+          renderer.render(engine).pixels,
+        );
+
+        expect(
+          _countDifferentPixels(partialFrame, mainMenuFrame),
+          greaterThan(0),
+        );
+
+        engine.menuManager.tickTransition(
+          MenuManager.transitionDurationMs ~/ 4,
+        );
+        final List<int> midpointFrame = List<int>.from(
+          renderer.render(engine).pixels,
+        );
+
+        expect(midpointFrame.every((pixel) => pixel == bgColor), isTrue);
+
+        engine.menuManager.tickTransition(
+          MenuManager.transitionDurationMs ~/ 2,
+        );
+        final List<int> completedFrame = List<int>.from(
+          renderer.render(engine).pixels,
+        );
+        final List<int> expectedDifficultyFrame = List<int>.from(
+          renderer.render(difficultyEngine).pixels,
+        );
+
+        expect(completedFrame, orderedEquals(expectedDifficultyFrame));
+      },
+    );
+  });
+}
+
+WolfEngine _buildEngine({required FrameBuffer frameBuffer}) {
+  return WolfEngine(
+    data: _buildTestData(),
+    difficulty: null,
+    startingEpisode: 0,
+    frameBuffer: frameBuffer,
+    input: _TestInput(),
+    engineAudio: _SilentAudio(),
+    onGameWon: () {},
+  );
+}
+
+WolfensteinData _buildTestData() {
+  final wallGrid = _buildGrid();
+  final objectGrid = _buildGrid();
+
+  _fillBoundaries(wallGrid, 2);
+  objectGrid[2][2] = MapObject.playerEast;
+
+  return WolfensteinData(
+    version: GameVersion.retail,
+    dataVersion: DataVersion.unknown,
+    registry: RetailAssetRegistry(),
+    walls: [
+      _solidSprite(1),
+      _solidSprite(1),
+      _solidSprite(2),
+      _solidSprite(2),
+    ],
+    sprites: List.generate(436, (_) => _solidSprite(255)),
+    sounds: List.generate(200, (_) => PcmSound(Uint8List(1))),
+    adLibSounds: const [],
+    music: const [],
+    vgaImages: const [],
+    episodes: [
+      Episode(
+        name: 'Episode 1',
+        levels: [
+          WolfLevel(
+            name: 'Level 1',
+            wallGrid: wallGrid,
+            areaGrid: List.generate(64, (_) => List.filled(64, -1)),
+            objectGrid: objectGrid,
+            music: Music.level01,
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+class _TestInput extends Wolf3dInput {
+  @override
+  void update() {}
+}
+
+class _SilentAudio implements EngineAudio {
+  @override
+  WolfensteinData? activeGame;
+
+  @override
+  Future<void> debugSoundTest() async {}
+
+  @override
+  Future<void> init() async {}
+
+  @override
+  void playLevelMusic(Music music) {}
+
+  @override
+  void playMenuMusic() {}
+
+  @override
+  void playSoundEffect(SoundEffect effect) {}
+
+  @override
+  void playSoundEffectId(int sfxId) {}
+
+  @override
+  void stopMusic() {}
+
+  @override
+  Future<void> stopAllAudio() async {}
+
+  @override
+  void dispose() {}
+}
+
+int _countDifferentPixels(List<int> a, List<int> b) {
+  int count = 0;
+  for (int i = 0; i < a.length; i++) {
+    if (a[i] != b[i]) {
+      count++;
+    }
+  }
+  return count;
+}
+
+int _rgbToFrameColor(int rgb) {
+  final int r = (rgb >> 16) & 0xFF;
+  final int g = (rgb >> 8) & 0xFF;
+  final int b = rgb & 0xFF;
+  return 0xFF000000 | (b << 16) | (g << 8) | r;
+}
+
+SpriteMap _buildGrid() => List.generate(64, (_) => List.filled(64, 0));
+
+void _fillBoundaries(SpriteMap grid, int wallId) {
+  for (int i = 0; i < 64; i++) {
+    grid[0][i] = wallId;
+    grid[63][i] = wallId;
+    grid[i][0] = wallId;
+    grid[i][63] = wallId;
+  }
+}
+
+Sprite _solidSprite(int colorIndex) {
+  return Sprite(Uint8List.fromList(List.filled(64 * 64, colorIndex)));
+}