Improved action animations in sprites

sky/sdk/example/game/lib/action.dart

Index: sky/sdk/example/game/lib/action.dart
diff --git a/sky/sdk/example/game/lib/action.dart b/sky/sdk/example/game/lib/action.dart
index 0c6119d528a3937a7b938b18fba62953699ac465..54073173e09704e9f75bb4c1c9825c0b4dbd6bfe 100644
--- a/sky/sdk/example/game/lib/action.dart
+++ b/sky/sdk/example/game/lib/action.dart
@@ -5,11 +5,16 @@ typedef void ActionCallback();
 abstract class Action {
   Object _tag;
   bool _finished = false;
+  bool _added = false;
 
   void step(double dt);
   void update(double t) {
   }
 
+  void _reset() {
+    _finished = false;
+  }
+
   double get duration => 0.0;
 }
 
@@ -20,8 +25,9 @@ abstract class ActionInterval extends Action {
   double _elapsed = 0.0;
 
   double get duration => _duration;
+  Curve curve;
 
-  ActionInterval([this._duration = 0.0]);
+  ActionInterval([this._duration = 0.0, this.curve]);
 
   void step(double dt) {
     if (_firstTick) {
@@ -37,7 +43,11 @@ abstract class ActionInterval extends Action {
       t = (_elapsed / _duration).clamp(0.0, 1.0);
     }
 
-    update(t);
+    if (curve == null) {
+      update(t);
+    } else {
+      update(curve.transform(t));
+    }
 
     if (t >= 1.0) _finished = true;
   }
@@ -46,13 +56,53 @@ abstract class ActionInterval extends Action {
 class ActionRepeat extends ActionInterval {
   final int numRepeats;
   final ActionInterval action;
+  int _lastFinishedRepeat = -1;
 
   ActionRepeat(this.action, this.numRepeats) {
     _duration = action.duration * numRepeats;
   }
 
   void update(double t) {
-    action.update((t * numRepeats.toDouble()) % numRepeats.toDouble());
+    int currentRepeat = Math.min((t * numRepeats.toDouble()).toInt(), numRepeats - 1);
+    for (int i = Math.max(_lastFinishedRepeat, 0); i < currentRepeat; i++) {
+      if (!action._finished) action.update(1.0);
+      action._reset();
+    }
+    _lastFinishedRepeat = currentRepeat;
+
+    double ta = (t * numRepeats.toDouble()) % 1.0;
+    action.update(ta);
+
+    if (t >= 1.0) {
+      action.update(1.0);
+      action._finished = true;
+    }
+  }
+}
+
+class ActionRepeatForever extends Action {
+  final ActionInterval action;
+  double _elapsedInAction = 0.0;
+
+  ActionRepeatForever(this.action);
+
+  step(double dt) {
+    _elapsedInAction += dt;
+    while (_elapsedInAction > action.duration) {
+      _elapsedInAction -= action.duration;
+      if (!action._finished) action.update(1.0);
+      action._reset();
+    }
+    _elapsedInAction = Math.max(_elapsedInAction, 0.0);
+
+    double t;
+    if (action._duration == 0.0) {
+      t = 1.0;
+    } else {
+      t = (_elapsedInAction / action._duration).clamp(0.0, 1.0);
+    }
+
+    action.update(t);
   }
 }
 
@@ -91,21 +141,107 @@ class ActionSequence extends ActionInterval {
       } else {
         ta = 1.0;
       }
-      _a.update(ta);
+      _updateWithCurve(_a, ta);
     } else if (t >= 1.0) {
       // Make sure everything is finished
-      if (!_a._finished) _a.update(1.0);
-      if (!_b._finished) _b.update(1.0);
+      if (!_a._finished) _finish(_a);
+      if (!_b._finished) _finish(_b);
     } else {
       // Play second action, but first make sure the first has finished
-      if (!_a._finished) _a.update(1.0);
+      if (!_a._finished) _finish(_a);
       double tb;
       if (_split < 1.0) {
         tb = (1.0 - (1.0 - t) / (1.0 - _split)).clamp(0.0, 1.0);
       } else {
         tb = 1.0;
       }
-      _b.update(tb);
+      _updateWithCurve(_b, tb);
+    }
+  }
+
+  void _updateWithCurve(Action action, double t) {
+    if (action is ActionInterval) {
+      ActionInterval actionInterval = action;
+      if (actionInterval.curve == null) {
+        action.update(t);
+      } else {
+        action.update(actionInterval.curve.transform(t));
+      }
+    } else {
+      action.update(t);
+    }
+
+    if (t >= 1.0) {
+      action._finished = true;
+    }
+  }
+
+  void _finish(Action action) {
+    action.update(1.0);
+    action._finished = true;
+  }
+
+  void _reset() {
+    super._reset();
+    _a._reset();
+    _b._reset();
+  }
+}
+
+class ActionGroup extends ActionInterval {
+  List<Action> _actions;
+
+  ActionGroup(this._actions) {
+    for (Action action in _actions) {
+      if (action.duration > _duration) {
+        _duration = action.duration;
+      }
+    }
+  }
+
+  void update(double t) {
+    if (t >= 1.0) {
+      // Finish all unfinished actions
+      for (Action action in _actions) {
+        if (!action._finished) {
+          action.update(1.0);
+          action._finished = true;
+        }
+      }
+    } else {
+      for (Action action in _actions) {
+        if (action.duration == 0.0) {
+          // Fire all instant actions immediately
+          if (!action._finished) {
+            action.update(1.0);
+            action._finished = true;
+          }
+        } else {
+          // Update child actions
+          double ta = (t / (action.duration / duration)).clamp(0.0, 1.0);
+          if (ta < 1.0) {
+            if (action is ActionInterval) {
+              ActionInterval actionInterval = action;
+              if (actionInterval.curve == null) {
+                action.update(ta);
+              } else {
+                action.update(actionInterval.curve.transform(ta));
+              }
+            } else {
+              action.update(ta);
+            }
+          } else if (!action._finished){
+            action.update(1.0);
+            action._finished = true;
+          }
+        }
+      }
+    }
+  }
+
+  void _reset() {
+    for (Action action in _actions) {
+      action._reset();
     }
   }
 }
@@ -143,30 +279,6 @@ class ActionRemoveNode extends ActionInstant {
   }
 }
 
-class ActionRepeatForever extends Action {
-  final ActionInterval action;
-  double _elapsedInAction = 0.0;
-
-  ActionRepeatForever(this.action);
-
-  step(double dt) {
-    _elapsedInAction += dt;
-    while (_elapsedInAction > action.duration) {
-      _elapsedInAction -= action.duration;
-    }
-    _elapsedInAction = Math.max(_elapsedInAction, 0.0);
-
-    double t;
-    if (action._duration == 0.0) {
-      t = 1.0;
-    } else {
-      t = (_elapsedInAction / action._duration).clamp(0.0, 1.0);
-    }
-
-    action.update(t);
-  }
-}
-
 class ActionTween extends ActionInterval {
   final Function setter;
   final startVal;
@@ -174,20 +286,41 @@ class ActionTween extends ActionInterval {
 
   var _delta;
 
-  ActionTween(this.setter, this.startVal, this.endVal, double duration) : super(duration) {
+  ActionTween(this.setter, this.startVal, this.endVal, double duration, [Curve curve]) : super(duration, curve) {
     _computeDelta();
   }
 
   void _computeDelta() {
     if (startVal is Point) {
+      // Point
       double xStart = startVal.x;
       double yStart = startVal.y;
       double xEnd = endVal.x;
       double yEnd = endVal.y;
       _delta = new Point(xEnd - xStart, yEnd - yStart);
+    } else if (startVal is Size) {
+      // Size
+      double wStart = startVal.width;
+      double hStart = startVal.height;
+      double wEnd = endVal.width;
+      double hEnd = endVal.height;
+      _delta = new Size(wEnd - wStart, hEnd - hStart);
+    } else if (startVal is Rect) {
+      // Rect
+      double lStart = startVal.left;
+      double tStart = startVal.top;
+      double rStart = startVal.right;
+      double bStart = startVal.bottom;
+      double lEnd = endVal.left;
+      double tEnd = endVal.top;
+      double rEnd = endVal.right;
+      double bEnd = endVal.bottom;
+      _delta = new Rect.fromLTRB(lEnd - lStart, tEnd - tStart, rEnd - rStart, bEnd - bStart);
     } else if (startVal is double) {
+      // Double
       _delta = endVal - startVal;
     } else if (startVal is Color) {
+      // Color
       int aDelta = endVal.alpha - startVal.alpha;
       int rDelta = endVal.red - startVal.red;
       int gDelta = endVal.green - startVal.green;
@@ -208,6 +341,24 @@ class ActionTween extends ActionInterval {
       double xDelta = _delta.x;
       double yDelta = _delta.y;
       newVal = new Point(xStart + xDelta * t, yStart + yDelta * t);
+    } else if (startVal is Size) {
+      // Size
+      double wStart = startVal.width;
+      double hStart = startVal.height;
+      double wDelta = _delta.width;
+      double hDelta = _delta.height;
+      newVal = new Size(wStart + wDelta * t, hStart + hDelta * t);
+    } else if (startVal is Rect) {
+      // Rect
+      double lStart = startVal.left;
+      double tStart = startVal.top;
+      double rStart = startVal.right;
+      double bStart = startVal.bottom;
+      double lDelta = _delta.left;
+      double tDelta = _delta.top;
+      double rDelta = _delta.right;
+      double bDelta = _delta.bottom;
+      newVal = new Rect.fromLTRB(lStart + lDelta * t, tStart + tDelta * t, rStart + rDelta * t, bStart + bDelta * t);
     } else if (startVal is double) {
       // Doubles
       newVal = startVal + _delta * t;
@@ -234,27 +385,41 @@ class ActionController {
   ActionController();
 
   void run(Action action, [Object tag]) {
+    assert(!action._added);
+
     action._tag = tag;
+    action._added = true;
     action.update(0.0);
     _actions.add(action);
   }
 
   void stop(Action action) {
-    _actions.remove(action);
+    if (_actions.remove(action)) {
+      action._added = false;
+      action._reset();
+    }
+  }
+
+  void _stopAtIndex(int i) {
+    Action action = _actions[i];
+    action._added = false;
+    action._reset();
+    _actions.removeAt(i);
   }
 
   void stopWithTag(Object tag) {
     for (int i = _actions.length - 1; i >= 0; i--) {
       Action action = _actions[i];
       if (action._tag == tag) {
-        _actions.removeAt(i);
-        print("removing tag: $tag");
+        _stopAtIndex(i);
       }
     }
   }
 
   void stopAll() {
-    _actions.clear();
+    for (int i = _actions.length - 1; i >= 0; i--) {
+      _stopAtIndex(i);
+    }
   }
 
   void step(double dt) {
@@ -263,6 +428,7 @@ class ActionController {
       action.step(dt);
 
       if (action._finished) {
+        action._added = false;
         _actions.removeAt(i);
       }
     }
@@ -276,4 +442,29 @@ class _ColorDiff {
   final int blue;
 
   _ColorDiff(this.alpha, this.red, this.green, this.blue);
-}
+}
+
+double _bounce(double t)
+{
+  if (t < 1.0 / 2.75) {
+    return 7.5625 * t * t;
+  } else if (t < 2 / 2.75) {
+    t -= 1.5 / 2.75;
+    return 7.5625 * t * t + 0.75;
+  } else if (t < 2.5 / 2.75) {
+    t -= 2.25 / 2.75;
+    return 7.5625 * t * t + 0.9375;
+  }
+  t -= 2.625 / 2.75;
+  return 7.5625 * t * t + 0.984375;
+}
+
+class BounceOutCurve implements Curve {
+  const BounceOutCurve();
+
+  double transform(double t) {
+    return _bounce(t);
+  }
+}
+
+const BounceOutCurve bounceOut = const BounceOutCurve();