function HemisphericLight(name, direction, scene) {
            var _this = _super.call(this, name, scene) || this;
            _this.groundColor = new BABYLON.Color3(0.0, 0.0, 0.0);
            _this.direction = direction || BABYLON.Vector3.Up();
            return _this;
        }
Creates a HemisphericLight object in the scene according to the passed direction (Vector3).
The HemisphericLight simulates the ambient environment light, so the passed direction is the light reflection direction, not the incoming direction.
The HemisphericLight can't cast shadows.
Documentation : http://doc.babylonjs.com/tutorials/lights