three.js中创建辅助坐标系

drawCoordSystem.js

    /* 绘制坐标系
     * scene —— 要绘制坐标系的场景（let scene = new THREE.Scene()）
     */
    function drawCoordSystem(scene) {
        // 创建三个坐标轴的几何模型
        let geometryX = new THREE.Geometry();
        geometryX.vertices.push(
            new THREE.Vector3(-5, 0, 0),
            new THREE.Vector3(5, 0, 0),
            new THREE.Vector3(4.8, 0.2, 0)
        );
        let geometryY = new THREE.Geometry();
        geometryY.vertices.push(
            new THREE.Vector3(0, -5, 0),
            new THREE.Vector3(0, 5, 0),
            new THREE.Vector3(0.2, 4.8, 0)
        );
        let geometryZ = new THREE.Geometry();
        geometryZ.vertices.push(
            new THREE.Vector3(0, 0, -5),
            new THREE.Vector3(0, 0, 5),
            new THREE.Vector3(0, 0.2, 4.8)
        );

        // 选择材料
        let materialX = new THREE.LineBasicMaterial({ color: 0xff0000 });
        let materialY = new THREE.LineBasicMaterial({ color: 0x00ff00 });
        let materialZ = new THREE.LineBasicMaterial({ color: 0x0000ff });

        // 创建对象
        let axisX = new THREE.Line(geometryX, materialX);
        let axisY = new THREE.Line(geometryY, materialY);
        let axisZ = new THREE.Line(geometryZ, materialZ);

        // 添加到场景中
        scene.add(axisX);
        scene.add(axisY);
        scene.add(axisZ);
    }