Adds basic touch handling to sprites and optimizes transformations

sky/examples/game/lib/game_demo_box.dart

Index: sky/examples/game/lib/game_demo_box.dart
diff --git a/sky/examples/game/lib/game_demo_box.dart b/sky/examples/game/lib/game_demo_box.dart
index 58716a1d14b8b728fb75a1108047248c2aa84fb7..2b9f0c4d325651b3ec27e0231ee9bc46418af3e0 100644
--- a/sky/examples/game/lib/game_demo_box.dart
+++ b/sky/examples/game/lib/game_demo_box.dart
@@ -14,66 +14,66 @@ class GameDemoBox extends SpriteBox {
   int _secondPointer = -1;
   Point _firstPointerDownPos;
 
-  void handleEvent(Event event, BoxHitTestEntry entry) {
-    if (event is PointerEvent) {
-      Point pointerPos = new Point(event.x, event.y);
-      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;
-            _gameWorld.controlFire();
-          }
-          else {
-            // There is a pointer used for steering, let's fire instead
-            _gameWorld.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;
-            }
-
-            _gameWorld.controlSteering(joystickX, joystickY);
-          }
-          break;
-        case 'pointerup':
-        case 'pointercancel':
-          if (pointer == _firstPointer) {
-            // Un-assign the first pointer
-            _firstPointer = -1;
-            _firstPointerDownPos = null;
-            _gameWorld.controlSteering(0.0, 0.0);
-          }
-          else if (pointer == _secondPointer) {
-            _secondPointer = -1;
-          }
-          break;
-        default:
-          break;
-      }
-    }
-  }
+//  void handleEvent(Event event, BoxHitTestEntry entry) {
+//    if (event is PointerEvent) {
+//      Point pointerPos = new Point(event.x, event.y);
+//      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;
+//            _gameWorld.controlFire();
+//          }
+//          else {
+//            // There is a pointer used for steering, let's fire instead
+//            _gameWorld.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;
+//            }
+//
+//            _gameWorld.controlSteering(joystickX, joystickY);
+//          }
+//          break;
+//        case 'pointerup':
+//        case 'pointercancel':
+//          if (pointer == _firstPointer) {
+//            // Un-assign the first pointer
+//            _firstPointer = -1;
+//            _firstPointerDownPos = null;
+//            _gameWorld.controlSteering(0.0, 0.0);
+//          }
+//          else if (pointer == _secondPointer) {
+//            _secondPointer = -1;
+//          }
+//          break;
+//        default:
+//          break;
+//      }
+//    }
+//  }
 
 }