anchor.diff:  
     double _emitCounter;
     int _numEmittedParticles = 0;
  +
  +  double opacity = 1.0;
   
     static Paint _paint = new Paint()
       ..filterQuality = ui.FilterQuality.low
  
positive.code:         } else {
            particleColor = colorSequence.colorAtPosition(particle.colorPos);
          }
          colors.add(particleColor);
        }
      }
  
negative.code:   }
  
    void paint(Canvas canvas) {
      if (opacity == 0.0) return;
  
      List<ui.RSTransform> transforms = <ui.RSTransform>[];
      List<Rect> rects = <Rect>[];
  