feat: clampLength for Vector2 extension (#2190)

With this method you can clamp the length of a vector, instead fitting it in a box like clamp and clampScalar does.

examples/lib/stories/rendering/isometric_tile_map_example.dart

@@ -32,6 +32,7 @@ class IsometricTileMapExample extends FlameGame with MouseMovementDetector {
 
   @override
   Future<void> onLoad() async {
+    debugMode = true;
     final tilesetImage = await images.load('tile_maps/tiles$suffix.png');
     final tileset = SpriteSheet(
       image: tilesetImage,

packages/flame/lib/src/extensions/vector2.dart

@@ -80,6 +80,21 @@ extension Vector2Extension on Vector2 {
     }
   }
 
+  /// Clamps the [length] of this vector.
+  ///
+  /// This means that if the length is less than [min] the length will be set to
+  /// [min] and if the length is larger than [max], the length will be set to
+  /// [max]. If the length is in between [min] and [max], no changes will be
+  /// made.
+  void clampLength(double min, double max) {
+    final lengthSquared = length2;
+    if (lengthSquared > max * max) {
+      scaleTo(max);
+    } else if (lengthSquared < min * min) {
+      scaleTo(min);
+    }
+  }
+
   /// Project this onto [other].
   ///
   /// [other] needs to have a length > 0;

packages/flame/test/extensions/vector2_test.dart

@@ -213,6 +213,28 @@ void main() {
       });
     });
 
+    group('clampLength', () {
+      test('clamp length min', () {
+        final v = Vector2(1, 0)..clampLength(2.0, 3.0);
+        expect(v.length, 2.0);
+      });
+
+      test('clamp length max', () {
+        final v = Vector2(1, 0)..clampLength(0.5, 0.8);
+        expect(v.length, 0.8);
+      });
+
+      test('clamp negative vector', () {
+        final v = Vector2(-1, -1)..clampLength(0.5, 0.8);
+        expect(v.length, 0.8);
+      });
+
+      test('no effect on vector in range', () {
+        final v = Vector2(1, 0)..clampLength(0.5, 2.0);
+        expect(v.length, 1.0);
+      });
+    });
+
     group('projection', () {
       test('Project onto longer vector', () {
         final u = Vector2(5, 2);