Renamed doc to docs and minor language fixes

doc/examples/box2d/contact_callbacks/lib/main.dart

@@ -1,154 +0,0 @@
-import 'dart:math' as math;
-import 'package:flame/box2d/box2d_component.dart';
-import 'package:flame/box2d/box2d_game.dart';
-import 'package:flame/box2d/contact_callbacks.dart';
-import 'package:flame/flame.dart';
-import 'package:flame/palette.dart';
-import 'package:flutter/material.dart';
-import 'package:box2d_flame/box2d.dart';
-
-import 'boundaries.dart';
-
-void main() async {
-  WidgetsFlutterBinding.ensureInitialized();
-  await Flame.util.fullScreen();
-  final MyBox2D box = MyBox2D();
-  final MyGame game = MyGame(box);
-  runApp(game.widget);
-}
-
-class Ball extends BodyComponent {
-  Paint originalPaint, currentPaint;
-  bool giveNudge = false;
-
-  Ball(Vector2 position, Box2DComponent box) : super(box) {
-    originalPaint = _randomPaint();
-    currentPaint = originalPaint;
-    Vector2 worldPosition = viewport.getScreenToWorld(position);
-    _createBody(5.0, worldPosition);
-  }
-
-  Paint _randomPaint() {
-    math.Random rng = math.Random();
-    return PaletteEntry(Color.fromARGB(100 + rng.nextInt(155),
-            100 + rng.nextInt(155), 100 + rng.nextInt(155), 255))
-        .paint;
-  }
-
-  void _createBody(double radius, Vector2 position) {
-    final CircleShape shape = CircleShape();
-    shape.radius = radius;
-
-    final fixtureDef = FixtureDef()
-      ..shape = shape
-      ..restitution = 1.0
-      ..density = 1.0
-      ..friction = 0.1;
-
-    final bodyDef = BodyDef()
-      // To be able to determine object in collision
-      ..setUserData(this)
-      ..position = position
-      ..type = BodyType.DYNAMIC;
-
-    body = world.createBody(bodyDef)..createFixtureFromFixtureDef(fixtureDef);
-  }
-
-  @override
-  bool destroy() {
-    // Implement your logic for when the component should be removed
-    return false;
-  }
-
-  @override
-  void renderCircle(Canvas c, Offset p, double radius) {
-    Paint blue = PaletteEntry(Colors.blue).paint;
-    c.drawCircle(p, radius, currentPaint);
-    double angle = body.getAngle();
-    Offset lineRotation =
-        Offset(math.sin(angle) * radius, math.cos(angle) * radius);
-    c.drawLine(p, p + lineRotation, blue);
-  }
-
-  @override
-  void update(double t) {
-    super.update(t);
-    if (giveNudge) {
-      body.applyLinearImpulse(Vector2(0, 10000), body.getLocalCenter(), true);
-      giveNudge = false;
-    }
-  }
-}
-
-class WhiteBall extends Ball {
-  WhiteBall(Vector2 position, Box2DComponent box) : super(position, box) {
-    originalPaint = BasicPalette.white.paint;
-    currentPaint = originalPaint;
-  }
-}
-
-class BallContactCallback extends ContactCallback<Ball, Ball> {
-  @override
-  void begin(Ball ball1, Ball ball2, Contact contact) {
-    if (ball1 is WhiteBall || ball2 is WhiteBall) {
-      return;
-    }
-    if (ball1.currentPaint != ball1.originalPaint) {
-      ball1.currentPaint = ball2.currentPaint;
-    } else {
-      ball2.currentPaint = ball1.currentPaint;
-    }
-  }
-
-  @override
-  void end(Ball ball1, Ball ball2, Contact contact) {}
-}
-
-class WhiteBallContactCallback extends ContactCallback<Ball, WhiteBall> {
-  @override
-  void begin(Ball ball, WhiteBall whiteBall, Contact contact) {
-    ball.giveNudge = true;
-  }
-
-  @override
-  void end(Ball ball, WhiteBall whiteBall, Contact contact) {}
-}
-
-class BallWallContactCallback extends ContactCallback<Ball, Wall> {
-  @override
-  void begin(Ball ball, Wall wall, Contact contact) {
-    wall.paint = ball.currentPaint;
-  }
-
-  @override
-  void end(Ball ball1, Wall wall, Contact contact) {}
-}
-
-class MyGame extends Box2DGame {
-  MyGame(Box2DComponent box) : super(box) {
-    final List<BodyComponent> boundaries = createBoundaries(box);
-    boundaries.forEach(add);
-    addContactCallback(BallContactCallback());
-    addContactCallback(BallWallContactCallback());
-    addContactCallback(WhiteBallContactCallback());
-  }
-
-  @override
-  void onTapDown(TapDownDetails details) {
-    super.onTapDown(details);
-    final Vector2 position =
-        Vector2(details.globalPosition.dx, details.globalPosition.dy);
-    if (math.Random().nextInt(10) < 2) {
-      add(WhiteBall(position, box));
-    } else {
-      add(Ball(position, box));
-    }
-  }
-}
-
-class MyBox2D extends Box2DComponent {
-  MyBox2D() : super(scale: 4.0, gravity: -10.0);
-
-  @override
-  void initializeWorld() {}
-}