Merge pull request #1050 from vlidholt/master

Demo game improvements

examples/game/lib/game_objects.dart

@@ -426,9 +426,13 @@ class EnemyBoss extends Obstacle {
     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);
+    f.level.addChild(_powerBar);
+    _powerBar.constraints = [new ConstraintPositionToNode(
+      this,
+      dampening: 0.5,
+      offset: new Offset(0.0, -70.0)
+    )];
   }
 
   Sprite _sprt;
@@ -446,8 +450,6 @@ class EnemyBoss extends Obstacle {
 
       _countDown = 60 + randomInt(120);
     }
-
-    _powerBar.rotation = -rotation;
   }
 
   void fire(double r) {
@@ -468,7 +470,27 @@ class EnemyBoss extends Obstacle {
 
   void destroy() {
     f.playerState.boss = null;
+    _powerBar.removeFromParent();
+
+    // Flash the screen
+    NodeWithSize screen = f.playerState.parent;
+    screen.addChild(new Flash(screen.size, 1.0));
     super.destroy();
+
+    // Add coins
+    for (int i = 0; i < 20; i++) {
+      Coin coin = new Coin(f);
+      Point pos = new Point(
+        randomSignedDouble() * 160,
+        position.y + randomSignedDouble() * 160.0);
+      f.addGameObject(coin, pos);
+    }
+  }
+
+  Explosion createExplosion() {
+    ExplosionBig explo = new ExplosionBig(f.sheet);
+    explo.scale = 1.5;
+    return explo;
   }
 
   set damage(double d) {

packages/flutter_sprites/lib/constraint.dart

@@ -70,3 +70,34 @@ class ConstraintRotationToNode extends Constraint {
     node.rotation = _dampenRotation(node.rotation, target, dampening);
   }
 }
+
+class ConstraintPositionToNode extends Constraint {
+  ConstraintPositionToNode(this.targetNode, {this.dampening, this.offset: Offset.zero});
+
+  final Node targetNode;
+  final Offset offset;
+  final double dampening;
+
+  void constrain(Node node, double dt) {
+    Point targetPosition;
+
+    if (targetNode.spriteBox != node.spriteBox || node.parent == null) {
+      // The target node is in another sprite box or has been removed
+      return;
+    }
+
+    if (targetNode.parent == node.parent) {
+      targetPosition = targetNode.position;
+    } else {
+      targetPosition = node.parent.convertPointFromNode(Point.origin, targetNode);
+    }
+
+    if (offset != null)
+      targetPosition += offset;
+
+    if (dampening == null)
+      node.position = targetPosition;
+    else
+      node.position = GameMath.filterPoint(node.position, targetPosition, dampening);
+  }
+}

packages/flutter_sprites/lib/util.dart

@@ -101,4 +101,8 @@ class GameMath {
   static double filter (double a, double b, double filterFactor) {
       return (a * (1-filterFactor)) + b * filterFactor;
   }
+
+  static Point filterPoint(Point a, Point b, double filterFactor) {
+    return new Point(filter(a.x, b.x, filterFactor), filter(a.y, b.y, filterFactor));
+  }
 }