code: function curveCalc(curveFrom, curveTo, progress) {
    var curve=[];
    for(var i=0,len1=curveFrom.length;i<len1;i++) {
      curve.push([curveFrom[i][0]]);
      for(var j=1,len2=curveFrom[i].length;j<len2;j++) {
        curve[i].push(curveFrom[i][j]+(curveTo[i][j]-curveFrom[i][j])*progress);
      }
    }
    return curve;
  }
docs: Calculate curve progress