加载Obj文件和测量工具

Question

我成功加载了一个obj文件，但我试图通过用两个点标记3d模型并在它们之间画一条直线来添加一个测量工具。像Potree这样的东西（不幸的是，它不支持.obj文件）。怎么能这样做因为我使用three.js。

Answer 1

1. 添加mousedown监听器
2. 从camera到鼠标位置的光线投射
3. 将交叉点A，B保存为Vector3
4. 计算A，B
之间的距离

缩短代码：

function onDocumentMouseDown( event ) {
    var vector = new THREE.Vector2();
    vector.set(
        ( event.clientX / window.innerWidth ) * 2 - 1,
        - ( event.clientY / window.innerHeight ) * 2 + 1 );

    var raycaster = new THREE.Raycaster();
    raycaster.setFromCamera( vector, camera );  

    var intersects = raycaster.intersectObjects( model.children );

    if ( intersects.length > 0 ) {

        pointA = intersects[ 0 ].point;
        // some logic to save pointB
        // on the second click...
        //pointB = intersects[ 0 ].point;

        var distance = pointA.distanceTo( pointB );

        // draw Line
        var geometry = new THREE.Geometry();
        geometry.vertices.push( pointA );
        geometry.vertices.push( pointB );
        var material = new THREE.LineBasicMaterial();
        line = new THREE.Line( geometry, material );
        scene.add(line);

    }
}

工作示例，距离输出在控制台中：http://jsfiddle.net/ev3tuLuc/95/