Automatically use sixel if it's available

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

apps/wolf_3d_cli/lib/cli_game_loop.dart

@@ -25,10 +25,10 @@ class CliGameLoop {
                'CliGameLoop requires a CliInput instance.',
              ),
 
-       primaryRenderer = AsciiRenderer(
+       primaryRenderer = SixelRenderer(),
+       secondaryRenderer = AsciiRenderer(
          mode: AsciiRendererMode.terminalAnsi,
-       ),
-       secondaryRenderer = SixelRenderer() {
+       ) {
     _renderer = primaryRenderer;
   }
 
@@ -44,6 +44,7 @@ class CliGameLoop {
   StreamSubscription<List<int>>? _stdinSubscription;
   Timer? _timer;
   bool _isRunning = false;
+  bool _isSixelAvailable = false;
   Duration _lastTick = Duration.zero;
 
   /// Starts terminal probing, enters raw input mode, and begins the frame timer.
@@ -57,6 +58,11 @@ class CliGameLoop {
       sixel.isSixelSupported = await SixelRenderer.checkTerminalSixelSupport(
         inputStream: _stdinStream,
       );
+      _isSixelAvailable = sixel.isSixelSupported;
+      _renderer = _isSixelAvailable ? primaryRenderer : secondaryRenderer;
+    } else {
+      _isSixelAvailable = false;
+      _renderer = secondaryRenderer;
     }
 
     if (stdin.hasTerminal) {
@@ -118,6 +124,9 @@ class CliGameLoop {
     }
 
     if (input.matchesRendererToggleShortcut(bytes)) {
+      if (!_isSixelAvailable) {
+        return;
+      }
       // Allow dynamic renderer-switch bindings configured on the CLI input.
       _renderer = identical(_renderer, secondaryRenderer)
           ? primaryRenderer
@@ -204,6 +213,9 @@ class CliGameLoop {
 
     final int safeCols = cols > 1 ? cols - 1 : cols;
     final String hint = _buildShortcutHintText();
+    if (hint.isEmpty) {
+      return;
+    }
     final String visible = hint.length > safeCols
         ? hint.substring(0, safeCols)
         : hint;
@@ -214,6 +226,14 @@ class CliGameLoop {
   }
 
   String _buildShortcutHintText() {
+    if (!_isSixelAvailable) {
+      if (_renderer is AsciiRenderer) {
+        final AsciiRenderer ascii = _renderer as AsciiRenderer;
+        return '<${input.asciiThemeCycleKeyLabel}> ${ascii.activeTheme.name}';
+      }
+      return '';
+    }
+
     final String rendererMode = _renderer is SixelRenderer ? 'sixel' : 'ascii';
     final String rendererHint =
         '<${input.rendererToggleKeyLabel}> $rendererMode';