flame_forge2d 0.20.0

Forge2D (Box2D) support for the Flame game engine. This uses the forge2d package and provides wrappers and components to be used inside Flame.

example/lib/main.dart

import 'package:flame/components.dart';
import 'package:flame/events.dart';
import 'package:flame/extensions.dart';
import 'package:flame/game.dart';
import 'package:flame_forge2d/flame_forge2d.dart';
import 'package:flutter/widgets.dart';

void main() {
  runApp(const GameWidget.managed(gameFactory: Forge2DExample.new));
}

class Forge2DExample extends Forge2DGame {
  @override
  Future<void> onLoad() async {
    await super.onLoad();

    camera.viewport.add(FpsTextComponent());
    world.add(Ball());
    world.addAll(createBoundaries());
  }

  List<Component> createBoundaries() {
    final visibleRect = camera.visibleWorldRect;
    final topLeft = visibleRect.topLeft.toVector2();
    final topRight = visibleRect.topRight.toVector2();
    final bottomRight = visibleRect.bottomRight.toVector2();
    final bottomLeft = visibleRect.bottomLeft.toVector2();

    return [
      Wall(topLeft, topRight),
      Wall(topRight, bottomRight),
      Wall(bottomLeft, bottomRight),
      Wall(topLeft, bottomLeft),
    ];
  }
}

/// A ball the size of a football, in a world measured in meters.
///
/// Forge2D is tuned for bodies roughly between 0.1 and 10 meters, so the
/// world is laid out at a realistic scale and the camera decides how large
/// that ends up being on screen.
class Ball extends BodyComponent with TapCallbacks {
  Ball({Vector2? initialPosition})
    : super(
        shapeSpecs: [
          ShapeSpec(
            Circle(radius: 0.5),
            ShapeDef(
              material: SurfaceMaterial(restitution: 0.8, friction: 0.4),
            ),
          ),
        ],
        bodyDef: BodyDef(
          angularDamping: 0.8,
          position: initialPosition ?? Vector2.zero(),
          type: BodyType.dynamic,
        ),
      );

  @override
  void onTapDown(_) {
    body.applyLinearImpulse(Vector2.random() * 5);
  }
}

class Wall extends BodyComponent {
  final Vector2 _start;
  final Vector2 _end;

  Wall(this._start, this._end);

  @override
  Body createBody() {
    final shapeDef = ShapeDef(material: SurfaceMaterial(friction: 0.3));
    final bodyDef = BodyDef(
      position: Vector2.zero(),
    );

    return world.createBody(bodyDef)
      ..createShape(Segment(point1: _start, point2: _end), shapeDef);
  }
}