Move sky/examples to sky/sdk/lib/example, and code changes to support that change. Fixes T277.

sky/examples/game/lib/game_demo_world.dart

-part of game;
-
-const double _steeringThreshold = 0.0;
-const double _steeringMax = 150.0;
-
-// Random generator
-Math.Random _rand = new Math.Random();
-
-const double _gameSizeWidth = 1024.0;
-const double _gameSizeHeight = 1024.0;
-
-const double _shipRadius = 30.0;
-const double _lrgAsteroidRadius = 40.0;
-const double _medAsteroidRadius = 20.0;
-const double _smlAsteroidRadius = 10.0;
-const double _maxAsteroidSpeed = 1.0;
-
-const int _lifeTimeLaser = 50;
-
-const int _numStarsInStarField = 150;
-
-class GameDemoWorld extends NodeWithSize {
-
-  // Images
-  Image _imgNebula;
-
-  SpriteSheet _spriteSheet;
-
-  // Inputs
-  double _joystickX = 0.0;
-  double _joystickY = 0.0;
-  bool _fire;
-
-  Node _gameLayer;
-
-  Ship _ship;
-  List<Asteroid> _asteroids = [];
-  List<Laser> _lasers = [];
-  StarField _starField;
-  Nebula _nebula;
-  
-  GameDemoWorld(ImageMap images, this._spriteSheet) : super(new Size(_gameSizeWidth, _gameSizeHeight)) {
-
-    // Fetch images
-    _imgNebula = images["res/nebula.png"];
-
-    _gameLayer = new Node();
-    this.addChild(_gameLayer);
-
-    // Add some asteroids to the game world
-    for (int i = 0; i < 5; i++) {
-      addAsteroid(AsteroidSize.large);
-    }
-    for (int i = 0; i < 5; i++) {
-      addAsteroid(AsteroidSize.medium);
-    }
-
-    // Add ship
-    addShip();
-
-    // Add starfield
-    _starField = new StarField(_spriteSheet["star.png"], _numStarsInStarField);
-    _starField.zPosition = -2.0;
-    addChild(_starField);
-
-    // Add nebula
-    addNebula();
-
-    userInteractionEnabled = true;
-    handleMultiplePointers = true;
-  }
-
-  // Methods for adding game objects
-  
-  void addAsteroid(AsteroidSize size, [Point pos]) {
-    Asteroid asteroid = new Asteroid(_spriteSheet["asteroid_big_1.png"], size);
-    asteroid.zPosition = 1.0;
-    if (pos != null) asteroid.position = pos;
-    _gameLayer.addChild(asteroid);
-    _asteroids.add(asteroid);
-  }
-
-  void addShip() {
-    Ship ship = new Ship(_spriteSheet["ship.png"]);
-    ship.zPosition = 10.0;
-    _gameLayer.addChild(ship);
-    _ship = ship;
-  }
-
-  void addLaser() {
-    Laser laser = new Laser(_spriteSheet["laser.png"], _ship);
-    laser.zPosition = 8.0;
-    _lasers.add(laser);
-    _gameLayer.addChild(laser);
-  }
-
-  void addNebula() {
-    _nebula = new Nebula.withImage(_imgNebula);
-    _gameLayer.addChild(_nebula);
-  }
-  
-  void update(double dt) {
-    // Move asteroids
-    for (Asteroid asteroid in _asteroids) {
-      asteroid.position = pointAdd(asteroid.position, asteroid._movementVector);
-    }
-
-    // Move lasers and remove expired lasers
-    for (int i = _lasers.length - 1; i >= 0; i--) {
-      Laser laser = _lasers[i];
-      laser.move();
-      if (laser._frameCount > _lifeTimeLaser) {
-        laser.removeFromParent();
-        _lasers.removeAt(i);
-      }
-    }
-
-    // Apply thrust to ship
-    if (_joystickX != 0.0 || _joystickY != 0.0) {
-      _ship.thrust(_joystickX, _joystickY);
-    }
-
-    // Move ship
-    _ship.move();
-
-    // Check collisions between asteroids and lasers
-    for (int i = _lasers.length -1; i >= 0; i--) {
-      // Iterate over all the lasers
-      Laser laser = _lasers[i];
-
-      for (int j = _asteroids.length - 1; j >= 0; j--) {
-        // Iterate over all the asteroids
-        Asteroid asteroid = _asteroids[j];
-
-        // Check for collision
-        if (pointQuickDist(laser.position, asteroid.position) < laser.radius + asteroid.radius) {
-          // Remove laser
-          laser.removeFromParent();
-          _lasers.removeAt(i);
-
-          // Add asteroids
-          if (asteroid._asteroidSize == AsteroidSize.large) {
-            for (int a = 0; a < 3; a++) addAsteroid(AsteroidSize.medium, asteroid.position);
-          }
-          else if (asteroid._asteroidSize == AsteroidSize.medium) {
-            for (int a = 0; a < 5; a++) addAsteroid(AsteroidSize.small, asteroid.position);
-          }
-
-          // Remove asteroid
-          asteroid.removeFromParent();
-          _asteroids.removeAt(j);
-          break;
-        }
-      }
-    }
-
-    // Move objects to center camera and warp objects around the edges
-    centerCamera();
-    warpObjects();
-  }
-
-  void centerCamera() {
-    const cameraDampening = 0.1;
-    Point delta = new Point(_gameSizeWidth/2 - _ship.position.x, _gameSizeHeight/2 - _ship.position.y);
-    delta = pointMult(delta, cameraDampening);
-
-    for (Node child in _gameLayer.children) {
-      child.position = pointAdd(child.position, delta);
-    }
-
-    // Update starfield
-    _starField.move(delta.x, delta.y);
-  }
-
-  void warpObjects() {
-    for (Node child in _gameLayer.children) {
-      if (child.position.x < 0) child.position = pointAdd(child.position, new Point(_gameSizeWidth, 0.0));
-      if (child.position.x >= _gameSizeWidth) child.position = pointAdd(child.position, new Point(-_gameSizeWidth, 0.0));
-      if (child.position.y < 0) child.position = pointAdd(child.position, new Point(0.0, _gameSizeHeight));
-      if (child.position.y >= _gameSizeHeight) child.position = pointAdd(child.position, new Point(0.0, -_gameSizeHeight));
-    }
-  }
-
-  // Handling controls
-
-  void controlSteering(double x, double y) {
-    _joystickX = x;
-    _joystickY = y;
-  }
-
-  void controlFire() {
-    addLaser();
-  }
-
-  // Handle pointer events
-
-  int _firstPointer = -1;
-  int _secondPointer = -1;
-  Point _firstPointerDownPos;
-
-  bool handleEvent(SpriteBoxEvent event) {
-    Point pointerPos = convertPointToNodeSpace(event.boxPosition);
-    int pointer = event.pointer;
-
-    switch (event.type) {
-      case 'pointerdown':
-        if (_firstPointer == -1) {
-          // Assign the first pointer
-          _firstPointer = pointer;
-          _firstPointerDownPos = pointerPos;
-        }
-        else if (_secondPointer == -1) {
-          // Assign second pointer
-          _secondPointer = pointer;
-          controlFire();
-        }
-        else {
-          // There is a pointer used for steering, let's fire instead
-          controlFire();
-        }
-        break;
-      case 'pointermove':
-        if (pointer == _firstPointer) {
-          // Handle turning control
-          double joystickX = 0.0;
-          double deltaX = pointerPos.x - _firstPointerDownPos.x;
-          if (deltaX > _steeringThreshold || deltaX < -_steeringThreshold) {
-            joystickX = (deltaX - _steeringThreshold)/(_steeringMax - _steeringThreshold);
-            if (joystickX > 1.0) joystickX = 1.0;
-            if (joystickX < -1.0) joystickX = -1.0;
-          }
-
-          double joystickY = 0.0;
-          double deltaY = pointerPos.y - _firstPointerDownPos.y;
-          if (deltaY > _steeringThreshold || deltaY < -_steeringThreshold) {
-            joystickY = (deltaY - _steeringThreshold)/(_steeringMax - _steeringThreshold);
-            if (joystickY > 1.0) joystickY = 1.0;
-            if (joystickY < -1.0) joystickY = -1.0;
-          }
-
-          controlSteering(joystickX, joystickY);
-        }
-        break;
-      case 'pointerup':
-      case 'pointercancel':
-        if (pointer == _firstPointer) {
-          // Un-assign the first pointer
-          _firstPointer = -1;
-          _firstPointerDownPos = null;
-          controlSteering(0.0, 0.0);
-        }
-        else if (pointer == _secondPointer) {
-          _secondPointer = -1;
-        }
-        break;
-      default:
-        break;
-    }
-    return true;
-  }
-}
-
-// Game objects
-
-enum AsteroidSize {
-  small,
-  medium,
-  large,
-}
-
-class Asteroid extends Sprite {
-  Point _movementVector;
-  AsteroidSize _asteroidSize;
-  double _radius;
-
-  double get radius {
-    if (_radius != null) return _radius;
-    if (_asteroidSize == AsteroidSize.small) _radius = _smlAsteroidRadius;
-    else if (_asteroidSize == AsteroidSize.medium) _radius = _medAsteroidRadius;
-    else if (_asteroidSize == AsteroidSize.large) _radius = _lrgAsteroidRadius;
-    return _radius;
-  }
-
-  Asteroid(Texture img, AsteroidSize this._asteroidSize) : super(img) {
-    size = new Size(radius * 2.0, radius * 2.0);
-    position = new Point(_gameSizeWidth * _rand.nextDouble(), _gameSizeHeight * _rand.nextDouble());
-    rotation = 360.0 * _rand.nextDouble();
-
-    _movementVector = new Point(_rand.nextDouble() * _maxAsteroidSpeed * 2 - _maxAsteroidSpeed,
-                                _rand.nextDouble() * _maxAsteroidSpeed * 2 - _maxAsteroidSpeed);
-
-    userInteractionEnabled = true;
-  }
-
-  bool handleEvent(SpriteBoxEvent event) {
-    if (event.type == "pointerdown") {
-      colorOverlay = new Color(0x99ff0000);
-    }
-    else if (event.type == "pointerup") {
-      colorOverlay = null;
-    }
-    return false;
-  }
-}
-
-class Ship extends Sprite {
-  Vector2 _movementVector;
-  double _rotationTarget;
-
-  Ship(Texture img) : super(img) {
-    _movementVector = new Vector2.zero();
-    rotation = _rotationTarget = 270.0;
-
-    // Create sprite
-    size = new Size(_shipRadius * 2.0, _shipRadius * 2.0);
-    position = new Point(_gameSizeWidth/2.0, _gameSizeHeight/2.0);
-  }
-
-  void thrust(double x, double y) {
-    _rotationTarget = convertRadians2Degrees(Math.atan2(y, x));
-    Vector2 directionVector = new Vector2(x, y).normalize();
-    _movementVector.addScaled(directionVector, 1.0);
-  }
-
-  void move() {
-    position = new Point(position.x + _movementVector[0], position.y + _movementVector[1]);
-    _movementVector.scale(0.9);
-
-    rotation = dampenRotation(rotation, _rotationTarget, 0.1);
-  }
-}
-
-class Laser extends Sprite {
-  int _frameCount = 0;
-  Point _movementVector;
-  double radius = 10.0;
-
-  Laser(Texture img, Ship ship) : super(img) {
-    size = new Size(20.0, 20.0);
-    position = ship.position;
-    rotation = ship.rotation + 90.0;
-    transferMode = TransferMode.plus;
-    double rotRadians = convertDegrees2Radians(rotation);
-    _movementVector = pointMult(new Point(Math.sin(rotRadians), -Math.cos(rotRadians)), 10.0);
-    _movementVector = new Point(_movementVector.x + ship._movementVector[0], _movementVector.y + ship._movementVector[1]);
-  }
-
-  void move() {
-    position = pointAdd(position, _movementVector);
-    _frameCount++;
-  }
-}
-
-// Background starfield
-
-class StarField extends Node {
-  Texture _img;
-  int _numStars;
-  List<Point> _starPositions;
-  List<double> _starScales;
-  List<double> _opacity;
-
-  StarField(this._img, this._numStars) {
-    _starPositions = [];
-    _starScales = [];
-    _opacity = [];
-
-    for (int i  = 0; i < _numStars; i++) {
-      _starPositions.add(new Point(_rand.nextDouble() * _gameSizeWidth, _rand.nextDouble() * _gameSizeHeight));
-      _starScales.add(_rand.nextDouble());
-      _opacity.add(_rand.nextDouble() * 0.5 + 0.5);
-    }
-  }
-
-  void paint(RenderCanvas canvas) {
-    // Setup paint object for opacity and transfer mode
-    Paint paint = new Paint();
-    paint.setTransferMode(TransferMode.plus);
-
-    double baseScaleX = 32.0 / _img.size.width;
-    double baseScaleY = 32.0 / _img.size.height;
-
-    // Draw each star
-    for (int i = 0; i < _numStars; i++) {
-      Point pos = _starPositions[i];
-      double scale = _starScales[i];
-      paint.color = new Color.fromARGB((255.0*_opacity[i]).toInt(), 255, 255, 255);
-
-      canvas.save();
-
-      canvas.translate(pos.x, pos.y);
-      canvas.scale(baseScaleX * scale, baseScaleY * scale);
-
-      canvas.drawImageRect(_img.image, _img.frame, _img.spriteSourceSize, paint);
-
-      canvas.restore();
-    }
-  }
-
-  void move(double dx, double dy) {
-    for (int i  = 0; i < _numStars; i++) {
-      double xPos = _starPositions[i].x;
-      double yPos = _starPositions[i].y;
-      double scale = _starScales[i];
-
-      xPos += dx * scale;
-      yPos += dy * scale;
-
-      if (xPos >= _gameSizeWidth) xPos -= _gameSizeWidth;
-      if (xPos < 0) xPos += _gameSizeWidth;
-      if (yPos >= _gameSizeHeight) yPos -= _gameSizeHeight;
-      if (yPos < 0) yPos += _gameSizeHeight;
-
-      _starPositions[i] = new Point(xPos, yPos);
-    }
-  }
-}
-
-class Nebula extends Node {
-
-  Nebula.withImage(Image img) {
-    for (int i = 0; i < 2; i++) {
-      for (int j = 0; j < 2; j++) {
-        Sprite sprt = new Sprite.fromImage(img);
-        sprt.pivot = Point.origin;
-        sprt.position = new Point(i * _gameSizeWidth - _gameSizeWidth, j * _gameSizeHeight - _gameSizeHeight);
-        addChild(sprt);
-      }
-    }
-  }
-}
-
-// Convenience methods
-
-Point pointAdd(Point a, Point b) {
-  return new Point(a.x+ b.x, a.y + b.y);
-}
-
-Point pointMult(Point a, double multiplier) {
-  return new Point(a.x * multiplier, a.y * multiplier);
-}
-
-double dampenRotation(double src, double dst, double dampening) {
-  double delta = dst - src;
-  while (delta > 180.0) delta -= 360;
-  while (delta < -180) delta += 360;
-  delta *= dampening;
-
-  return src + delta;
-}
-
-double pointQuickDist(Point a, Point b) {
-  double dx = a.x - b.x;
-  double dy = a.y - b.y;
-  if (dx < 0.0) dx = -dx;
-  if (dy < 0.0) dy = -dy;
-  if (dx > dy) {
-    return dx + dy/2.0;
-  }
-  else {
-    return dy + dx/2.0;
-  }
-}