Three.js 新舊版本建立幾何物件差異

昨天遇到個小問題，也搞了挺長時間：用Three.js在webgl中繪製三維物件，從網上抄的一段程式碼，執行報錯：

THREE.Geometry is not a constructor

納尼，找不到Geometry物件？

function createLine(){
        let start = new THREE.Vector3(7, 1.8, -2);
        let end = new THREE.Vector3(1.6,1.8, -2);

        // 就是這裡建立的物件找不到 *****
        let geometry = new THREE.Geometry();
        // ****************************

        let lineMaterial = new THREE.LineBasicMaterial({color: 0x00ff00});
        geometry.vertices.push(start);
        geometry.vertices.push(end);
        let line = new THREE.Line(lineGeometry, lineMaterial);
        scene.add(line);
        return line;
}

一開始還以為是模組匯入問題，折騰了一陣才發現，THREE模組中竟然真的就沒有Geometry！難道網上的程式碼是愚人節貼的？遇事不決問google，終於確認人家是升級了。新版的Three.js不再提供Geometry物件，代之以BufferGeometry，程式碼修改如下：

function createLine(){
        let start = new THREE.Vector3(7, 1.8, -2);
        let end = new THREE.Vector3(1.6,1.8, -2);

        let lineMaterial = new THREE.LineBasicMaterial({color: 0x00ff00});
        let pointsArray = [start, end];
        let lineGeometry = new THREE.BufferGeometry().setFromPoints(pointsArray);
        let line = new THREE.Line(lineGeometry, lineMaterial);
        scene.add(line);
        return line;
}