docs: Added bouncing ball example in collision_detection examples and updated flame_forge2d to latest (#1868)

This PR adds two updates.

It updates the flame_forge2d to latest version i.e on pub.dev in examples and padracing projects.

Adds a bouncing ball example in the collision detection examples demonstrating a simple example of collision and bouncing of a ball from the walls around it.

examples/games/padracing/pubspec.yaml

@@ -8,7 +8,7 @@ environment:
 
 dependencies:
   flame: ^1.3.0
-  flame_forge2d: ^0.11.0
+  flame_forge2d: ^0.12.2
   flutter:
     sdk: flutter
   google_fonts: ^2.3.2

examples/lib/stories/collision_detection/bouncing_ball_example.dart

@@ -0,0 +1,107 @@
+import 'dart:math' as math;
+import 'dart:ui';
+
+import 'package:flame/collisions.dart';
+import 'package:flame/components.dart';
+import 'package:flame/game.dart';
+import 'package:flutter/material.dart';
+
+class BouncingBallExample extends FlameGame with HasCollisionDetection {
+  static const description = '''
+    This example shows how you can use the Collisions detection api to know when a ball
+    collides with the screen boundaries and then update it to bounce off these boundaries.
+  ''';
+  @override
+  Future<void>? onLoad() {
+    addAll([
+      ScreenHitbox(),
+      Ball(),
+    ]);
+    return super.onLoad();
+  }
+}
+
+class Ball extends CircleComponent
+    with HasGameRef<FlameGame>, CollisionCallbacks {
+  late Vector2 velocity;
+
+  Ball() {
+    paint = Paint()..color = Colors.white;
+    radius = 10;
+  }
+
+  static const double speed = 500;
+  static const degree = math.pi / 180;
+
+  @override
+  Future<void>? onLoad() {
+    _resetBall;
+    final hitBox = CircleHitbox(
+      radius: radius,
+    );
+
+    addAll([
+      hitBox,
+    ]);
+
+    return super.onLoad();
+  }
+
+  @override
+  void update(double dt) {
+    super.update(dt);
+    position += velocity * dt;
+  }
+
+  void get _resetBall {
+    position = gameRef.size / 2;
+    final spawnAngle = getSpawnAngle;
+
+    final vx = math.cos(spawnAngle * degree) * speed;
+    final vy = math.sin(spawnAngle * degree) * speed;
+    velocity = Vector2(
+      vx,
+      vy,
+    );
+  }
+
+  double get getSpawnAngle {
+    final random = math.Random().nextDouble();
+    final spawnAngle = lerpDouble(0, 360, random)!;
+
+    return spawnAngle;
+  }
+
+  @override
+  void onCollisionStart(
+    Set<Vector2> intersectionPoints,
+    PositionComponent other,
+  ) {
+    super.onCollisionStart(intersectionPoints, other);
+
+    if (other is ScreenHitbox) {
+      final collisionPoint = intersectionPoints.first;
+
+      // Left Side Collision
+      if (collisionPoint.x == 0) {
+        velocity.x = -velocity.x;
+        velocity.y = velocity.y;
+      }
+      // Right Side Collision
+      if (collisionPoint.x == gameRef.size.x) {
+        velocity.x = -velocity.x;
+        velocity.y = velocity.y;
+      }
+      // Top Side Collision
+      if (collisionPoint.y == 0) {
+        velocity.x = velocity.x;
+        velocity.y = -velocity.y;
+      }
+      // Bottom Side Collision
+      if (collisionPoint.y == gameRef.size.y) {
+        velocity.x = velocity.x;
+        velocity.y = -velocity.y;
+      }
+    }
+  }
+}

examples/lib/stories/collision_detection/collision_detection.dart

@@ -1,5 +1,6 @@
 import 'package:dashbook/dashbook.dart';
 import 'package:examples/commons/commons.dart';
+import 'package:examples/stories/collision_detection/bouncing_ball_example.dart';
 import 'package:examples/stories/collision_detection/circles_example.dart';
 import 'package:examples/stories/collision_detection/collidable_animation_example.dart';
 import 'package:examples/stories/collision_detection/multiple_shapes_example.dart';
@@ -23,6 +24,12 @@ void addCollisionDetectionStories(Dashbook dashbook) {
       codeLink: baseLink('collision_detection/circles_example.dart'),
       info: CirclesExample.description,
     )
+    ..add(
+      'Bouncing Ball',
+      (_) => GameWidget(game: BouncingBallExample()),
+      codeLink: baseLink('collision_detection/bouncing_ball_example.dart'),
+      info: BouncingBallExample.description,
+    )
     ..add(
       'Multiple shapes',
       (_) => GameWidget(game: MultipleShapesExample()),

examples/pubspec.yaml

@@ -13,7 +13,7 @@ dependencies:
   dashbook: 0.1.8
   flame: ^1.3.0
   flame_audio: ^1.3.1
-  flame_forge2d: ^0.11.0
+  flame_forge2d: ^0.12.2
   flame_svg: ^1.5.0
   flutter:
     sdk: flutter