Adds power bar and movements to boss fights in demo game

examples/game/lib/custom_actions.dart

@@ -17,3 +17,17 @@ class ActionCircularMove extends ActionInterval {
     setter(pos);
   }
 }
+
+class ActionOscillate extends ActionInterval {
+  ActionOscillate(this.setter, this.center, this.radius, double duration) : super(duration);
+
+  final Function setter;
+  final Point center;
+  final double radius;
+
+  void update(double t) {
+    double rad = radians(t * 360.0);
+    Offset offset = new Offset(math.sin(rad) * radius, 0.0);
+    setter(center + offset);
+  }
+}

examples/game/lib/game_demo.dart

@@ -17,5 +17,6 @@ part 'game_demo_node.dart';
 part 'game_objects.dart';
 part 'game_object_factory.dart';
 part 'player_state.dart';
+part 'power_bar.dart';
 part 'repeated_image.dart';
 part 'star_field.dart';

examples/game/lib/game_objects.dart

@@ -426,9 +426,15 @@ class EnemyBoss extends Obstacle {
     maxDamage = 40.0;
 
     constraints = [new ConstraintRotationToNode(f.level.ship, dampening: 0.05)];
+
+    _powerBar = new PowerBar(new Size(60.0, 10.0));
+    _powerBar.position = new Point(-80.0, 0.0);
+    _powerBar.pivot = new Point(0.5, 0.5);
+    addChild(_powerBar);
   }
 
   Sprite _sprt;
+  PowerBar _powerBar;
 
   int _countDown = randomInt(120) + 240;
 
@@ -436,18 +442,49 @@ class EnemyBoss extends Obstacle {
     _countDown -= 1;
     if (_countDown <= 0) {
       // Shoot at player
-      EnemyLaser laser = new EnemyLaser(f, rotation, 5.0, new Color(0xffffe38e));
-      laser.position = position;
-      f.level.addChild(laser);
+      fire(10.0);
+      fire(0.0);
+      fire(-10.0);
 
       _countDown = 60 + randomInt(120);
     }
+
+    _powerBar.rotation = -rotation;
+  }
+
+  void fire(double r) {
+    r += rotation;
+    EnemyLaser laser = new EnemyLaser(f, r, 5.0, new Color(0xffffe38e));
+
+    double rad = radians(r);
+    Offset startOffset = new Offset(math.cos(rad) * 30.0, math.sin(rad) * 30.0);
+
+    laser.position = position + startOffset;
+    f.level.addChild(laser);
+  }
+
+  void setupActions() {
+    ActionOscillate oscillate = new ActionOscillate((a) => position = a, position, 120.0, 3.0);
+    actions.run(new ActionRepeatForever(oscillate));
   }
 
   void destroy() {
     f.playerState.boss = null;
     super.destroy();
   }
+
+  set damage(double d) {
+    super.damage = d;
+    _sprt.actions.stopAll();
+    _sprt.actions.run(new ActionTween(
+      (a) =>_sprt.colorOverlay = a,
+      new Color.fromARGB(180, 255, 3, 86),
+      new Color(0x00000000),
+      0.3
+    ));
+
+    _powerBar.power = (1.0 - (damage / maxDamage)).clamp(0.0, 1.0);
+  }
 }
 
 class Collectable extends GameObject {

examples/game/lib/power_bar.dart

@@ -0,0 +1,21 @@
+part of game;
+
+class PowerBar extends NodeWithSize {
+  PowerBar(Size size, [this.power = 1.0]) : super(size);
+
+  double power;
+
+  Paint _paintFill = new Paint()
+    ..color = new Color(0xffffffff);
+  Paint _paintOutline = new Paint()
+    ..color = new Color(0xffffffff)
+    ..strokeWidth = 1.0
+    ..setStyle(sky.PaintingStyle.stroke);
+
+  void paint(PaintingCanvas canvas) {
+    applyTransformForPivot(canvas);
+
+    canvas.drawRect(new Rect.fromLTRB(0.0, 0.0, size.width - 0.0, size.height - 0.0), _paintOutline);
+    canvas.drawRect(new Rect.fromLTRB(2.0, 2.0, (size.width - 2.0) * power, size.height - 2.0), _paintFill);
+  }
+}