refactor: use relative positioning

lib/game/components/plunger.dart

@@ -11,13 +11,16 @@ import 'package:pinball/game/game.dart' show Anchor;
 /// {@endtemplate}
 class Plunger extends BodyComponent with KeyboardHandler {
   /// {@macro plunger}
-  Plunger({required Vector2 position}) : _position = position;
+  Plunger({
+    required Vector2 position,
+    required this.compressionDistance,
+  }) : _position = position;
 
   /// The initial position of the [Plunger] body.
   final Vector2 _position;
 
   /// Distance the plunger can lower.
-  static const compressionDistance = 120.0;
+  final double compressionDistance;
 
   @override
   Body createBody() {
@@ -83,7 +86,7 @@ class PlungerAnchor extends Anchor {
   }) : super(
           position: Vector2(
             plunger.body.position.x,
-            plunger.body.position.y - Plunger.compressionDistance,
+            plunger.body.position.y - plunger.compressionDistance,
           ),
         );
 }

lib/game/pinball_game.dart

@@ -15,18 +15,6 @@ class PinballGame extends Forge2DGame
 
   late final Plunger plunger;
 
-  // TODO(erickzanardo): Change to the plumber position
-  late final ballStartingPosition = screenToWorld(
-        Vector2(
-          camera.viewport.effectiveSize.x / 2,
-          camera.viewport.effectiveSize.y - 20,
-        ),
-      ) -
-      Vector2(0, -20);
-
-  // TODO(alestiago): Change to the design position.
-  late final flippersPosition = ballStartingPosition - Vector2(0, 5);
-
   @override
   void onAttach() {
     super.onAttach();
@@ -80,7 +68,7 @@ class PinballGame extends Forge2DGame
     final flippersPosition = screenToWorld(
       Vector2(
         camera.viewport.effectiveSize.x / 2,
-        camera.viewport.effectiveSize.y - 120,
+        camera.viewport.effectiveSize.y / 1.1,
       ),
     );
     const spaceBetweenFlippers = 2;
@@ -144,15 +132,17 @@ class PinballGame extends Forge2DGame
 
   Future<void> _addPlunger() async {
     late PlungerAnchor plungerAnchor;
+    final compressionDistance = camera.viewport.effectiveSize.y / 12;
 
     await add(
       plunger = Plunger(
         position: screenToWorld(
           Vector2(
-            camera.viewport.effectiveSize.x - 30,
-            camera.viewport.effectiveSize.y - Plunger.compressionDistance,
+            camera.viewport.effectiveSize.x / 1.035,
+            camera.viewport.effectiveSize.y - compressionDistance,
           ),
         ),
+        compressionDistance: compressionDistance,
       ),
     );
     await add(plungerAnchor = PlungerAnchor(plunger: plunger));

test/game/components/plunger_test.dart

@@ -16,11 +16,16 @@ void main() {
   final flameTester = FlameTester(PinballGameX.initial);
 
   group('Plunger', () {
+    const compressionDistance = 0.0;
+
     flameTester.test(
       'loads correctly',
       (game) async {
         await game.ready();
-        final plunger = Plunger(position: Vector2.zero());
+        final plunger = Plunger(
+          position: Vector2.zero(),
+          compressionDistance: compressionDistance,
+        );
         await game.ensureAdd(plunger);
 
         expect(game.contains(plunger), isTrue);
@@ -32,7 +37,10 @@ void main() {
         'positions correctly',
         (game) async {
           final position = Vector2.all(10);
-          final plunger = Plunger(position: position);
+          final plunger = Plunger(
+            position: position,
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
           game.contains(plunger);
 
@@ -43,7 +51,10 @@ void main() {
       flameTester.test(
         'is dynamic',
         (game) async {
-          final plunger = Plunger(position: Vector2.zero());
+          final plunger = Plunger(
+            position: Vector2.zero(),
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
 
           expect(plunger.body.bodyType, equals(BodyType.dynamic));
@@ -53,7 +64,10 @@ void main() {
       flameTester.test(
         'ignores gravity',
         (game) async {
-          final plunger = Plunger(position: Vector2.zero());
+          final plunger = Plunger(
+            position: Vector2.zero(),
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
 
           expect(plunger.body.gravityScale, isZero);
@@ -65,7 +79,10 @@ void main() {
       flameTester.test(
         'exists',
         (game) async {
-          final plunger = Plunger(position: Vector2.zero());
+          final plunger = Plunger(
+            position: Vector2.zero(),
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
 
           expect(plunger.body.fixtures[0], isA<Fixture>());
@@ -75,7 +92,10 @@ void main() {
       flameTester.test(
         'shape is a polygon',
         (game) async {
-          final plunger = Plunger(position: Vector2.zero());
+          final plunger = Plunger(
+            position: Vector2.zero(),
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
 
           final fixture = plunger.body.fixtures[0];
@@ -86,7 +106,10 @@ void main() {
       flameTester.test(
         'has density',
         (game) async {
-          final plunger = Plunger(position: Vector2.zero());
+          final plunger = Plunger(
+            position: Vector2.zero(),
+            compressionDistance: compressionDistance,
+          );
           await game.ensureAdd(plunger);
 
           final fixture = plunger.body.fixtures[0];
@@ -105,7 +128,10 @@ void main() {
       late Plunger plunger;
 
       setUp(() {
-        plunger = Plunger(position: Vector2.zero());
+        plunger = Plunger(
+          position: Vector2.zero(),
+          compressionDistance: compressionDistance,
+        );
       });
 
       testRawKeyUpEvents(keys, (event) {
@@ -162,10 +188,15 @@ void main() {
   });
 
   group('PlungerAnchor', () {
+    const compressionDistance = 10.0;
+
     flameTester.test(
       'position is a compression distance below the Plunger',
       (game) async {
-        final plunger = Plunger(position: Vector2.zero());
+        final plunger = Plunger(
+          position: Vector2.zero(),
+          compressionDistance: compressionDistance,
+        );
         await game.ensureAdd(plunger);
 
         final plungerAnchor = PlungerAnchor(plunger: plunger);
@@ -173,16 +204,16 @@ void main() {
 
         expect(
           plungerAnchor.body.position.y,
-          equals(plunger.body.position.y - Plunger.compressionDistance),
+          equals(plunger.body.position.y - compressionDistance),
         );
       },
     );
   });
 
   group('PlungerAnchorPrismaticJointDef', () {
-    late Plunger plunger;
-
+    const compressionDistance = 10.0;
     final gameBloc = MockGameBloc();
+    late Plunger plunger;
 
     setUp(() {
       whenListen(
@@ -190,7 +221,10 @@ void main() {
         const Stream<GameState>.empty(),
         initialState: const GameState.initial(),
       );
-      plunger = Plunger(position: Vector2.zero());
+      plunger = Plunger(
+        position: Vector2.zero(),
+        compressionDistance: compressionDistance,
+      );
     });
 
     final flameTester = flameBlocTester(gameBloc: gameBloc);