Added the ability to exclude frames from a frame range. This will help with death animations where the sprites are out of order.

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

packages/wolf_3d_dart/lib/src/data_types/sprite_frame_range.dart

@@ -1,13 +1,28 @@
-/// Represents a slice of indices within a sprite list for animation states.
+/// Represents a slice of indices within a sprite list for animation states,
+/// with the ability to skip specific frames.
 class SpriteFrameRange {
   final int start;
   final int end;
+  final Set<int> excluded;
 
-  const SpriteFrameRange(this.start, this.end);
+  const SpriteFrameRange(
+    this.start,
+    this.end, {
+    this.excluded = const {},
+  });
 
-  /// Total number of frames in this animation range.
-  int get length => end - start + 1;
+  /// Total number of frames in this animation range, excluding skipped indices.
+  int get length {
+    final baseLength = end - start + 1;
+    // Count how many excluded indices actually fall within the start/end bounds
+    final exclusionsInRange = excluded
+        .where((i) => i >= start && i <= end)
+        .length;
+    return baseLength - exclusionsInRange;
+  }
 
-  /// Checks if a specific sprite [index] is part of this animation range.
-  bool contains(int index) => index >= start && index <= end;
+  /// Checks if a specific sprite [index] is part of this range and not excluded.
+  bool contains(int index) {
+    return index >= start && index <= end && !excluded.contains(index);
+  }
 }