function rotateAroundWorldAxis( object, axis, radians ) {

    var rotationMatrix = new THREE.Matrix4();
    rotationMatrix.makeRotationAxis( axis.normalize(), radians );
    rotationMatrix.multiply( object.matrix );                       // pre-multiply
    object.matrix = rotationMatrix;
    object.rotation.setFromRotationMatrix(object.matrix);
}

function render() {

        var yAxis = new THREE.Vector3(0,1,0);
        rotateAroundWorldAxis(albero,yAxis,Math.PI / 180);
        requestAnimationFrame( render );
        renderer.render( scene, camera );
    }

var rotObjectMatrix;
    function rotateAroundObjectAxis(object, axis, radians) {
        rotObjectMatrix = new THREE.Matrix4();
        rotObjectMatrix.makeRotationAxis(axis.normalize(), radians);
        object.matrix.multiply(rotObjectMatrix);
        object.rotation.setFromRotationMatrix(object.matrix);
    }

function drawStuff() {


    var albero = new THREE.Object3D();
    var scene = new THREE.Scene();
    var camera = new THREE.PerspectiveCamera( 55, window.innerWidth / window.innerHeight, 0.1, 1000 );

    var renderer = new THREE.WebGLRenderer();
    renderer.setSize( window.innerWidth, window.innerHeight );
    document.body.appendChild( renderer.domElement );


    var cone = createCone(0, 0, 0); //create cone of the tree
    var cylinder = createCylinder(0, -1.1, 0); //create cylinder of the tree
    albero = createAlbero(-4, 2, 3);

    scene.add(albero);

    var axisHelper = new THREE.AxisHelper( 5 );
    scene.add( axisHelper );

    camera.position.z = 20;


    function createCone(x, y, z){
        var coneGeometry = new THREE.CylinderGeometry(0.0, 0.7, 2, 32, 32);
        var coneMaterial = new THREE.MeshBasicMaterial( {color: 0xFF0000} );
        var cone = new THREE.Mesh( coneGeometry, coneMaterial );
        cone.position.set(x, y, z);
        return cone;
    }

  function createCylinder(x, y, z){

        var cylGeometry = new THREE.CylinderGeometry(0.1, 0.1, 0.4, 32, 32);
        var cylinderMaterial = new THREE.MeshBasicMaterial( {color: 0xffff00} );
        var cylinder = new THREE.Mesh( cylGeometry, cylinderMaterial );
        cylinder.position.set(x, y, z);
        return cylinder;

    }

  function createAlbero(x ,y, z){

        albero.add(cone);
        albero.add(cylinder);
        albero.position.set(x ,y, z);
        return albero;
    }

    var rotObjectMatrix;
    function rotateAroundObjectAxis(object, axis, radians) {
        rotObjectMatrix = new THREE.Matrix4();
        rotObjectMatrix.makeRotationAxis(axis.normalize(), radians);

        //moltiplico la matrice dell'oggetto per la matrice di rotazione
        object.matrix.multiply(rotObjectMatrix);

        object.rotation.setFromRotationMatrix(object.matrix);
    }


    function rotateAroundWorldAxis( object, axis, radians ) {

        var rotationMatrix = new THREE.Matrix4();

        rotationMatrix.makeRotationAxis( axis.normalize(), radians );
        rotationMatrix.multiply( object.matrix );                       // pre-multiply
        object.matrix = rotationMatrix;
        object.rotation.setFromRotationMatrix(object.matrix);
    }



    function render() {

        var yAxis = new THREE.Vector3(30,50,1);
        rotateAroundWorldAxis(cone2,yAxis,Math.PI / 180);
        requestAnimationFrame( render );
        renderer.render( scene, camera );
    }
    render();


}