refactor: initial position to ramps and cleaned ramp callbacks

lib/game/components/jetpack_ramp.dart

@@ -34,25 +34,25 @@ class JetpackRamp extends Component with HasGameRef<PinballGame> {
         angle: _angle,
         rotation: _rotation,
         layer: Layer.jetpack,
-      ),
+      )..initialPosition = position,
     );
 
     await add(
       JetpackRampOpening(
-        position: position + Vector2(-11, 1),
         orientation: RampOrientation.down,
         rotation: radians(15),
-      ),
+      )..initialPosition = position + Vector2(-11, 1),
     );
     await add(
       JetpackRampOpening(
-        position: position + Vector2(20.5, 3.4),
         orientation: RampOrientation.down,
         rotation: radians(-9),
-      ),
+      )..initialPosition = position + Vector2(20.5, 3.4),
     );
 
-    gameRef.addContactCallback(JetpackRampOpeningBallContactCallback());
+    gameRef.addContactCallback(
+      RampOpeningBallContactCallback<JetpackRampOpening>(),
+    );
   }
 }
 
@@ -63,13 +63,11 @@ class JetpackRamp extends Component with HasGameRef<PinballGame> {
 class JetpackRampOpening extends RampOpening {
   /// {@macro jetpack_ramp_opening}
   JetpackRampOpening({
-    required Vector2 position,
     required RampOrientation orientation,
     double rotation = 0,
   })  : _rotation = rotation,
         _orientation = orientation,
         super(
-          position: position,
           pathwayLayer: Layer.jetpack,
           openingLayer: Layer.opening,
         );
@@ -97,19 +95,3 @@ class JetpackRampOpening extends RampOpening {
       Vector2(_size / 2, -.1)..rotate(_rotation),
     ]);
 }
-
-/// {@template jetpack_ramp_opening_ball_contact_callback}
-/// Detects when a [Ball] enters or exits the [JetpackRamp] through a
-/// [JetpackRampOpening].
-/// {@endtemplate}
-class JetpackRampOpeningBallContactCallback
-    extends RampOpeningBallContactCallback<JetpackRampOpening> {
-  /// {@macro jetpack_ramp_opening_ball_contact_callback}
-  JetpackRampOpeningBallContactCallback() : super();
-
-  /// Collection of balls inside [JetpackRamp].
-  final _ballsInsideJetpack = <Ball>{};
-
-  @override
-  Set get ballsInside => _ballsInsideJetpack;
-}

lib/game/components/launcher_ramp.dart

@@ -33,7 +33,7 @@ class LauncherRamp extends Component with HasGameRef<PinballGame> {
         end: Vector2(0, 600),
         width: 80,
         layer: Layer.launcher,
-      ),
+      )..initialPosition = position,
     );
 
     await add(
@@ -44,23 +44,23 @@ class LauncherRamp extends Component with HasGameRef<PinballGame> {
         angle: _angle,
         width: _width,
         layer: Layer.launcher,
-      ),
+      )..initialPosition = position + Vector2(-28.8, -6),
     );
     await add(
       LauncherRampOpening(
-        position: position + Vector2(-46.5, -8.5),
         orientation: RampOrientation.down,
         rotation: radians(13),
-      ),
+      )..initialPosition = position + Vector2(-46.5, -8.5),
     );
     await add(
       LauncherRampOpening(
-        position: position + Vector2(4, 0),
         orientation: RampOrientation.down,
-      ),
+      )..initialPosition = position + Vector2(4, 0),
     );
 
-    gameRef.addContactCallback(LauncherRampOpeningBallContactCallback());
+    gameRef.addContactCallback(
+      RampOpeningBallContactCallback<LauncherRampOpening>(),
+    );
   }
 }
 
@@ -71,13 +71,11 @@ class LauncherRamp extends Component with HasGameRef<PinballGame> {
 class LauncherRampOpening extends RampOpening {
   /// {@macro launcher_ramp_opening}
   LauncherRampOpening({
-    required Vector2 position,
     double rotation = 0,
     required RampOrientation orientation,
   })  : _rotation = rotation,
         _orientation = orientation,
         super(
-          position: position,
           pathwayLayer: Layer.launcher,
           openingLayer: Layer.opening,
         );
@@ -105,19 +103,3 @@ class LauncherRampOpening extends RampOpening {
       Vector2(_size / 2, -.1)..rotate(_rotation),
     ]);
 }
-
-/// {@template launcher_ramp_opening_ball_contact_callback}
-/// Detects when a [Ball] enters or exits the [LauncherRamp] through a
-/// [LauncherRampOpening].
-/// {@endtemplate}
-class LauncherRampOpeningBallContactCallback
-    extends RampOpeningBallContactCallback<LauncherRampOpening> {
-  /// {@macro launcher_ramp_opening_ball_contact_callback}
-  LauncherRampOpeningBallContactCallback() : super();
-
-  /// Collection of balls inside [LauncherRamp].
-  final _ballsInsideLauncher = <Ball>{};
-
-  @override
-  Set get ballsInside => _ballsInsideLauncher;
-}

lib/game/components/layer.dart

@@ -79,27 +79,24 @@ enum RampOrientation {
 /// through this opening. By default openings are [Layer.board] that
 /// means opening are at ground level, not over board.
 /// {@endtemplate}
-abstract class RampOpening extends BodyComponent {
+abstract class RampOpening extends BodyComponent with InitialPosition {
   /// {@macro ramp_opening}
   RampOpening({
-    required Vector2 position,
     required Layer pathwayLayer,
     Layer? openingLayer,
-  })  : _position = position,
+  })  : _pathwayLayer = pathwayLayer,
-        _pathwayLayer = pathwayLayer,
         _openingLayer = openingLayer ?? Layer.board;
 
-  final Vector2 _position;
   final Layer _openingLayer;
   final Layer _pathwayLayer;
 
-  /// Mask of category bits for collision with [RampOpening]
+  /// Mask of category bits for collision with [RampOpening].
   Layer get openingLayer => _openingLayer;
 
-  /// Mask of category bits for collision inside [Pathway]
+  /// Mask of category bits for collision inside [Pathway].
   Layer get pathwayLayer => _pathwayLayer;
 
-  /// The [Shape] of the [RampOpening]
+  /// The [Shape] of the [RampOpening].
   Shape get shape;
 
   /// Orientation of the [RampOpening] entrance/exit
@@ -115,7 +112,7 @@ abstract class RampOpening extends BodyComponent {
 
     final bodyDef = BodyDef()
       ..userData = this
-      ..position = _position
+      ..position = initialPosition
       ..type = BodyType.static;
 
     return world.createBody(bodyDef)..createFixture(fixtureDef);
@@ -129,10 +126,10 @@ abstract class RampOpening extends BodyComponent {
 /// Modifies [Ball]'s maskBits while it is inside the ramp. When [Ball] exits,
 /// sets maskBits to collide with all elements.
 /// {@endtemplate}
-abstract class RampOpeningBallContactCallback<Opening extends RampOpening>
+class RampOpeningBallContactCallback<Opening extends RampOpening>
     extends ContactCallback<Ball, Opening> {
   /// Collection of balls inside ramp pathway.
-  Set get ballsInside;
+  final _ballsInside = <Ball>{};
 
   @override
   void begin(
@@ -141,12 +138,12 @@ abstract class RampOpeningBallContactCallback<Opening extends RampOpening>
     Contact _,
   ) {
     Layer layer;
-    if (!ballsInside.contains(ball)) {
+    if (!_ballsInside.contains(ball)) {
       layer = opening.pathwayLayer;
-      ballsInside.add(ball);
+      _ballsInside.add(ball);
     } else {
       layer = Layer.board;
-      ballsInside.remove(ball);
+      _ballsInside.remove(ball);
     }
 
     ball.layer = layer;
@@ -158,12 +155,12 @@ abstract class RampOpeningBallContactCallback<Opening extends RampOpening>
 
     switch (opening.orientation) {
       case RampOrientation.up:
-        if (ball.body.position.y > opening._position.y) {
+        if (ball.body.position.y > opening.body.position.y) {
           layer = Layer.board;
         }
         break;
       case RampOrientation.down:
-        if (ball.body.position.y < opening._position.y) {
+        if (ball.body.position.y < opening.body.position.y) {
           layer = Layer.board;
         }
         break;