'POSITION'];
            let dis = 0;
            for (let i = 0; i < positions.length / 3 - 1; i++) {
                const a = Math.pow( positions[i * 3] - positions[(i+1) * 3], 2);
                const b = Math.pow( positions[i * 3 + 1] - positions[(i+1) * 3 + 1], 2);
                const c =  Math.pow( positions[i * 3 + 2] - positions[(i+1) * 3 + 2], 2);
                dis += Math.sqrt(a + b + c);
            }
            return dis;
        }

        function calArea(geometry) {
            if (!g