feat: add slingshots (#148)

* feat: add slingshots

* test: slingshot

* feat: add slingshot to sandbox

* chore: add todo

lib/game/game_assets.dart

@@ -15,6 +15,10 @@ extension PinballGameAssetsX on PinballGame {
       images.load(components.Assets.images.baseboard.right.keyName),
       images.load(components.Assets.images.kicker.left.keyName),
       images.load(components.Assets.images.kicker.right.keyName),
+      images.load(components.Assets.images.slingshot.leftUpper.keyName),
+      images.load(components.Assets.images.slingshot.leftLower.keyName),
+      images.load(components.Assets.images.slingshot.rightUpper.keyName),
+      images.load(components.Assets.images.slingshot.rightLower.keyName),
       images.load(components.Assets.images.launchRamp.ramp.keyName),
       images.load(
         components.Assets.images.launchRamp.foregroundRailing.keyName,

lib/game/pinball_game.dart

@@ -46,6 +46,7 @@ class PinballGame extends Forge2DGame
     await add(plunger);
 
     unawaited(add(Board()));
+    unawaited(addFromBlueprint(Slingshots()));
     unawaited(addFromBlueprint(DinoWalls()));
     unawaited(_addBonusWord());
     unawaited(addFromBlueprint(SpaceshipRamp()));

packages/pinball_components/lib/gen/assets.gen.dart

@@ -29,6 +29,7 @@ class $AssetsImagesGen {
   $AssetsImagesKickerGen get kicker => const $AssetsImagesKickerGen();
   $AssetsImagesLaunchRampGen get launchRamp =>
       const $AssetsImagesLaunchRampGen();
+  $AssetsImagesSlingshotGen get slingshot => const $AssetsImagesSlingshotGen();
   $AssetsImagesSpaceshipGen get spaceship => const $AssetsImagesSpaceshipGen();
   $AssetsImagesSparkyBumperGen get sparkyBumper =>
       const $AssetsImagesSparkyBumperGen();
@@ -127,6 +128,26 @@ class $AssetsImagesLaunchRampGen {
       const AssetGenImage('assets/images/launch_ramp/ramp.png');
 }
 
+class $AssetsImagesSlingshotGen {
+  const $AssetsImagesSlingshotGen();
+
+  /// File path: assets/images/slingshot/left_lower.png
+  AssetGenImage get leftLower =>
+      const AssetGenImage('assets/images/slingshot/left_lower.png');
+
+  /// File path: assets/images/slingshot/left_upper.png
+  AssetGenImage get leftUpper =>
+      const AssetGenImage('assets/images/slingshot/left_upper.png');
+
+  /// File path: assets/images/slingshot/right_lower.png
+  AssetGenImage get rightLower =>
+      const AssetGenImage('assets/images/slingshot/right_lower.png');
+
+  /// File path: assets/images/slingshot/right_upper.png
+  AssetGenImage get rightUpper =>
+      const AssetGenImage('assets/images/slingshot/right_upper.png');
+}
+
 class $AssetsImagesSpaceshipGen {
   const $AssetsImagesSpaceshipGen();
 

packages/pinball_components/lib/src/components/components.dart

@@ -16,6 +16,7 @@ export 'launch_ramp.dart';
 export 'layer.dart';
 export 'ramp_opening.dart';
 export 'shapes/shapes.dart';
+export 'slingshot.dart';
 export 'spaceship.dart';
 export 'spaceship_rail.dart';
 export 'spaceship_ramp.dart';

packages/pinball_components/lib/src/components/slingshot.dart

@@ -0,0 +1,138 @@
+// ignore_for_file: avoid_renaming_method_parameters
+
+import 'dart:math' as math;
+
+import 'package:flame/components.dart';
+import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:pinball_components/pinball_components.dart';
+
+/// {@template slingshots}
+/// A [Blueprint] which creates the left and right pairs of [Slingshot]s.
+/// {@endtemplate}
+class Slingshots extends Forge2DBlueprint {
+  @override
+  void build(_) {
+    // TODO(allisonryan0002): use radians values instead of converting degrees.
+    final leftUpperSlingshot = Slingshot(
+      length: 5.66,
+      angle: -1.5 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.leftUpper.keyName,
+    )..initialPosition = Vector2(-29, 1.5);
+
+    final leftLowerSlingshot = Slingshot(
+      length: 3.54,
+      angle: -29.1 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.leftLower.keyName,
+    )..initialPosition = Vector2(-31, -6.2);
+
+    final rightUpperSlingshot = Slingshot(
+      length: 5.64,
+      angle: 1 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.rightUpper.keyName,
+    )..initialPosition = Vector2(22.3, 1.58);
+
+    final rightLowerSlingshot = Slingshot(
+      length: 3.46,
+      angle: 26.8 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.rightLower.keyName,
+    )..initialPosition = Vector2(24.7, -6.2);
+
+    addAll([
+      leftUpperSlingshot,
+      leftLowerSlingshot,
+      rightUpperSlingshot,
+      rightLowerSlingshot,
+    ]);
+  }
+}
+
+/// {@template slingshot}
+/// Elastic bumper that bounces the [Ball] off of its straight sides.
+/// {@endtemplate}
+class Slingshot extends BodyComponent with InitialPosition {
+  /// {@macro slingshot}
+  Slingshot({
+    required double length,
+    required double angle,
+    required String spritePath,
+  })  : _length = length,
+        _angle = angle,
+        _spritePath = spritePath,
+        super(priority: 1);
+
+  final double _length;
+
+  final double _angle;
+
+  final String _spritePath;
+
+  List<FixtureDef> _createFixtureDefs() {
+    final fixturesDef = <FixtureDef>[];
+    const circleRadius = 1.55;
+
+    final topCircleShape = CircleShape()..radius = circleRadius;
+    topCircleShape.position.setValues(0, _length / 2);
+    final topCircleFixtureDef = FixtureDef(topCircleShape)..friction = 0;
+    fixturesDef.add(topCircleFixtureDef);
+
+    final bottomCircleShape = CircleShape()..radius = circleRadius;
+    bottomCircleShape.position.setValues(0, -_length / 2);
+    final bottomCircleFixtureDef = FixtureDef(bottomCircleShape)..friction = 0;
+    fixturesDef.add(bottomCircleFixtureDef);
+
+    final leftEdgeShape = EdgeShape()
+      ..set(
+        Vector2(circleRadius, _length / 2),
+        Vector2(circleRadius, -_length / 2),
+      );
+    final leftEdgeShapeFixtureDef = FixtureDef(leftEdgeShape)
+      ..friction = 0
+      ..restitution = 5;
+    fixturesDef.add(leftEdgeShapeFixtureDef);
+
+    final rightEdgeShape = EdgeShape()
+      ..set(
+        Vector2(-circleRadius, _length / 2),
+        Vector2(-circleRadius, -_length / 2),
+      );
+    final rightEdgeShapeFixtureDef = FixtureDef(rightEdgeShape)
+      ..friction = 0
+      ..restitution = 5;
+    fixturesDef.add(rightEdgeShapeFixtureDef);
+
+    return fixturesDef;
+  }
+
+  @override
+  Body createBody() {
+    final bodyDef = BodyDef()
+      ..userData = this
+      ..position = initialPosition
+      ..angle = _angle;
+
+    final body = world.createBody(bodyDef);
+    _createFixtureDefs().forEach(body.createFixture);
+
+    return body;
+  }
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+    await _loadSprite();
+    renderBody = false;
+  }
+
+  Future<void> _loadSprite() async {
+    final sprite = await gameRef.loadSprite(_spritePath);
+
+    await add(
+      SpriteComponent(
+        sprite: sprite,
+        size: sprite.originalSize / 10,
+        anchor: Anchor.center,
+        angle: _angle,
+      ),
+    );
+  }
+}

packages/pinball_components/pubspec.yaml

@@ -39,6 +39,7 @@ flutter:
     - assets/images/spaceship/ramp/
     - assets/images/chrome_dino/
     - assets/images/kicker/
+    - assets/images/slingshot/
     - assets/images/sparky_bumper/a/
     - assets/images/sparky_bumper/b/
     - assets/images/sparky_bumper/c/

packages/pinball_components/sandbox/lib/main.dart

@@ -21,6 +21,7 @@ void main() {
   addChromeDinoStories(dashbook);
   addDashNestBumperStories(dashbook);
   addKickerStories(dashbook);
+  addSlingshotStories(dashbook);
   addSparkyBumperStories(dashbook);
   runApp(dashbook);
 }

packages/pinball_components/sandbox/lib/stories/slingshot/slingshot_game.dart

@@ -0,0 +1,66 @@
+import 'dart:math' as math;
+
+import 'package:flame/extensions.dart';
+import 'package:pinball_components/pinball_components.dart';
+import 'package:sandbox/common/common.dart';
+import 'package:sandbox/stories/ball/basic_ball_game.dart';
+
+class SlingshotGame extends BasicBallGame {
+  SlingshotGame({
+    required this.trace,
+  }) : super(color: const Color(0xFFFF0000));
+
+  static const info = '''
+    Shows how Slingshots are rendered.
+
+    - Activate the "trace" parameter to overlay the body.
+    - Tap anywhere on the screen to spawn a ball into the game.
+''';
+
+  final bool trace;
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+
+    final center = screenToWorld(camera.viewport.canvasSize! / 2);
+
+    final leftUpperSlingshot = Slingshot(
+      length: 5.66,
+      angle: -1.5 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.leftUpper.keyName,
+    )..initialPosition = center + Vector2(-29, 1.5);
+
+    final leftLowerSlingshot = Slingshot(
+      length: 3.54,
+      angle: -29.1 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.leftLower.keyName,
+    )..initialPosition = center + Vector2(-31, -6.2);
+
+    final rightUpperSlingshot = Slingshot(
+      length: 5.64,
+      angle: 1 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.rightUpper.keyName,
+    )..initialPosition = center + Vector2(22.3, 1.58);
+
+    final rightLowerSlingshot = Slingshot(
+      length: 3.46,
+      angle: 26.8 * (math.pi / 180),
+      spritePath: Assets.images.slingshot.rightLower.keyName,
+    )..initialPosition = center + Vector2(24.7, -6.2);
+
+    await addAll([
+      leftUpperSlingshot,
+      leftLowerSlingshot,
+      rightUpperSlingshot,
+      rightLowerSlingshot,
+    ]);
+
+    if (trace) {
+      leftUpperSlingshot.trace();
+      leftLowerSlingshot.trace();
+      rightUpperSlingshot.trace();
+      rightLowerSlingshot.trace();
+    }
+  }
+}

packages/pinball_components/sandbox/lib/stories/slingshot/stories.dart

@@ -0,0 +1,17 @@
+import 'package:dashbook/dashbook.dart';
+import 'package:flame/game.dart';
+import 'package:sandbox/common/common.dart';
+import 'package:sandbox/stories/slingshot/slingshot_game.dart';
+
+void addSlingshotStories(Dashbook dashbook) {
+  dashbook.storiesOf('Slingshots').add(
+        'Basic',
+        (context) => GameWidget(
+          game: SlingshotGame(
+            trace: context.boolProperty('Trace', true),
+          ),
+        ),
+        codeLink: buildSourceLink('slingshot_game/basic.dart'),
+        info: SlingshotGame.info,
+      );
+}

packages/pinball_components/sandbox/lib/stories/stories.dart

@@ -5,5 +5,6 @@ export 'dash_nest_bumper/stories.dart';
 export 'effects/stories.dart';
 export 'flipper/stories.dart';
 export 'layer/stories.dart';
+export 'slingshot/stories.dart';
 export 'spaceship/stories.dart';
 export 'sparky_bumper/stories.dart';

packages/pinball_components/test/src/components/slingshot_test.dart

@@ -0,0 +1,97 @@
+// ignore_for_file: cascade_invocations
+
+import 'package:flame_forge2d/flame_forge2d.dart';
+import 'package:flame_test/flame_test.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pinball_components/pinball_components.dart';
+
+import '../../helpers/helpers.dart';
+
+void main() {
+  group('Slingshot', () {
+    final flameTester = FlameTester(TestGame.new);
+    const length = 2.0;
+    const angle = 0.0;
+    final spritePath = Assets.images.slingshot.leftUpper.keyName;
+
+    flameTester.testGameWidget(
+      'renders correctly',
+      setUp: (game, tester) async {
+        await game.addFromBlueprint(Slingshots());
+        await game.ready();
+        game.camera.followVector2(Vector2.zero());
+      },
+      // TODO(allisonryan0002): enable test when workflows are fixed.
+      // verify: (game, tester) async {
+      //   await expectLater(
+      //     find.byGame<Forge2DGame>(),
+      //     matchesGoldenFile('golden/slingshots.png'),
+      //   );
+      // },
+    );
+
+    flameTester.test(
+      'loads correctly',
+      (game) async {
+        final slingshot = Slingshot(
+          length: length,
+          angle: angle,
+          spritePath: spritePath,
+        );
+        await game.ensureAdd(slingshot);
+
+        expect(game.contains(slingshot), isTrue);
+      },
+    );
+
+    flameTester.test(
+      'body is static',
+      (game) async {
+        final slingshot = Slingshot(
+          length: length,
+          angle: angle,
+          spritePath: spritePath,
+        );
+        await game.ensureAdd(slingshot);
+
+        expect(slingshot.body.bodyType, equals(BodyType.static));
+      },
+    );
+
+    flameTester.test(
+      'has restitution',
+      (game) async {
+        final slingshot = Slingshot(
+          length: length,
+          angle: angle,
+          spritePath: spritePath,
+        );
+        await game.ensureAdd(slingshot);
+
+        final totalRestitution = slingshot.body.fixtures.fold<double>(
+          0,
+          (total, fixture) => total + fixture.restitution,
+        );
+        expect(totalRestitution, greaterThan(0));
+      },
+    );
+
+    flameTester.test(
+      'has no friction',
+      (game) async {
+        final slingshot = Slingshot(
+          length: length,
+          angle: angle,
+          spritePath: spritePath,
+        );
+        await game.ensureAdd(slingshot);
+
+        final totalFriction = slingshot.body.fixtures.fold<double>(
+          0,
+          (total, fixture) => total + fixture.friction,
+        );
+        expect(totalFriction, equals(0));
+      },
+    );
+  });
+}