Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div ng-controller="MyCtrl">

 <div ng-repeat="group in groups">
  <div ng-repeat="material in materialsByGroup(group)">
      <div>{{group.name}}</div>
      <div>{{material.name}}</div>
  </div>
</div>

</div>

JavaScript

var myApp = angular.module('myApp',[]);

myApp.filter('test', function(group) {
    
});

function MyCtrl($scope) {
    
    var groups = [
        {'name':'group one'},
        {'name':'group two'}
    ];
    
    var materials = [
        {'name':'material1', groups:[]},
        {'name':'material2', groups:[groups[0], groups[1]]},
        {'name':'material3', groups:[groups[0]]}
    ];
    
    $scope.groups = groups;
    $scope.materials = materials;

    $scope.materialsByGroup = function(group){
        for(var i=0; i<materials.length; i++){
            if (materials[i].groups.length > 0){
                return materials[i].group.name === group.name ?
                    materials : null;
            }
            return null;
        }
    }
}