trackBallControls.noRotate = true;
            if (isDragging === true) {
                var deltaMove = {
                    x: event.offsetX -previousMousePosition.x,
                    y: event.offsetY -previousMousePosition.y
                };
                var deltaRotationQuaternion = new THREE.Quaternion()
                        .setFromEuler(new THREE.Euler(toRadians(deltaMove.y * 0.3),
                                toRadians(deltaMove.x * 0.3),
                                0,
                                'XYZ'
                                ));
                if (event.which === 1) {
                    mesh.quaternion.multiplyQuaternions(deltaRotationQuaternion, mesh.quaternion);
                }
            }
            previousMousePosition = {
                x: event.offsetX,
                y: event.offsetY
            };

function toRadians(angle) {
            return angle * (Math.PI / 180);
        }