Determining even and odd

[sdkevorkian]

Hello! I am trying to pass the index into the when-visible directive so that I have alternating scroll effects.
Here is what I have working:

 <div class="col s12 project not-visible animated" ng-repeat="project in projects track by $index" when-visible="animateElementIn" delay-percent="0.33">
</div>
...
        $scope.animateElementIn = function($el) {
            $el.removeClass('not-visible');
            $el.addClass('fadeInLeftBig');
        };

I tried to pass both $el and $index in like this:

when-visible="animateElementIn($el, $index)" 
...
        $scope.animateElementIn = function($el, $index) {
            $el.removeClass('not-visible');
            $el.addClass('fadeInLeftBig');
        };

but I get this error:

angular.js:13236 TypeError: Cannot read property 'removeClass' of undefined
at ChildScope.$scope.animateElementIn (file:///home/sara/portfolio/js/app.js:7:16)
at fn (eval at compile (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:14086:15), :4:386)
at Scope.destination.(anonymous function) [as whenVisible] (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:9603:22)
at new controller (file:///home/sara/portfolio/angular-scroll-animate/dist/angular-scroll-animate.js:82:61)
at Object.invoke (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:4604:19)
at extend.instance (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:9855:34)
at nodeLinkFn (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:8927:34)
at compositeLinkFn (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:8226:13)
at publicLinkFn (http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:8106:30)
at http://ajax.googleapis.com/ajax/libs/angularjs/1.5.0/angular.js:8447:29

is there a way to access the index (or odd/even) within the function called from where-visible?