feat: added generic area and area callback for ramps crossing

lib/game/components/crossing_ramp.dart

@@ -0,0 +1,81 @@
+import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:pinball/game/game.dart';
+
+enum RampType { all, jetpack, sparky }
+
+extension RampTypeX on RampType {
+  int get maskBits => _getRampMaskBits(this);
+
+  int _getRampMaskBits(RampType type) {
+    switch (type) {
+      case RampType.all:
+        return Filter().maskBits;
+      case RampType.jetpack:
+        return 0x010;
+      case RampType.sparky:
+        return 0x0100;
+    }
+  }
+}
+
+abstract class RampArea extends BodyComponent {
+  RampArea({
+    required Vector2 position,
+    required int maskBits,
+  })  : _position = position,
+        _maskBits = maskBits;
+
+  final Vector2 _position;
+  final int _maskBits;
+
+  int get maskBits => _maskBits;
+  Shape get shape;
+
+  @override
+  Body createBody() {
+    final fixtureDef = FixtureDef(shape)..isSensor = true;
+
+    final bodyDef = BodyDef()
+      ..userData = this
+      ..position = _position
+      ..type = BodyType.static;
+
+    final body = world.createBody(bodyDef);
+    body.createFixture(fixtureDef).filterData
+      ..categoryBits = Filter().maskBits
+      ..maskBits = Filter().maskBits;
+
+    return body;
+  }
+}
+
+abstract class RampAreaCallback<Area extends RampArea>
+    extends ContactCallback<Ball, Area> {
+  Set get ballsInside;
+
+  @override
+  void begin(
+    Ball ball,
+    Area area,
+    Contact _,
+  ) {
+    if (!ballsInside.contains(ball)) {
+      ball.body.fixtures.first
+        ..filterData.categoryBits = area.maskBits
+        ..filterData.maskBits = area.maskBits;
+      ballsInside.add(ball);
+    }
+  }
+
+  @override
+  void end(Ball ball, Area area, Contact ___) {
+    int maskBits;
+    if (ballsInside.contains(ball)) {
+      ball.body.fixtures.first
+        ..filterData.categoryBits = RampType.all.maskBits
+        ..filterData.maskBits = RampType.all.maskBits;
+
+      ballsInside.remove(ball);
+    }
+  }
+}