text: Xflow.registerOperator("xflow.add3", {
      outputs: [  {type: 'float3', name: 'result'}],
      params:  [  {type: 'float3', source: 'value1'},
                  {type: 'float3', source: 'value2'}],
      evaluate: function(result, value1, value2, info) {
          throw new Error("Not used!");
      },
      evaluate_core: function(result, value1, value2){
          result[0] = value1[0] + value2[0];
          result[1] = value1[1] + value2[1];
          result[2] = value1[2] + value2[2];
      }
  });
  