code: function styleNormCalc(styleNormFrom, styleNormTo, progress) {
    var i, len, styleNorm={};
    for(i in styleNormFrom) {
      switch (i) {
        case 'fill':
        case 'stroke':
          styleNorm[i]=clone(styleNormFrom[i]);
          styleNorm[i].r=styleNormFrom[i].r+(styleNormTo[i].r-styleNormFrom[i].r)*progress;
          styleNorm[i].g=styleNormFrom[i].g+(styleNormTo[i].g-styleNormFrom[i].g)*progress;
          styleNorm[i].b=styleNormFrom[i].b+(styleNormTo[i].b-styleNormFrom[i].b)*progress;
          styleNorm[i].opacity=styleNormFrom[i].opacity+(styleNormTo[i].opacity-styleNormFrom[i].opacity)*progress;
          break;
        case 'opacity':
        case 'fill-opacity':
        case 'stroke-opacity':
        case 'stroke-width':
          styleNorm[i]=styleNormFrom[i]+(styleNormTo[i]-styleNormFrom[i])*progress;
          break;
      }
    }
    return styleNorm;
  }
docs: Calculate style