在 Autodesk Forge 查看器中的元素下拾取

Posted 2023-03-16

【中文标题】在 Autodesk Forge 查看器中的元素下拾取

【英文标题】：Picking under elements of an element in Autodesk Forge viewer

【发布时间】：2017-05-07 01:14:21

【问题描述】：

我想完成一项可以在 Three.js 中完成但在 Autodesk Forge 查看器中无法完成的功能。以下是测试链接：http://app.netonapp.com/javascript/Three.js/select_inner_objects.html

要求是选择对象内的对象。这项工作可以在上面的演示中使用 THREE.Raycaster 来完成，使用 raycaster 来检测光线通过线上的所有元素。然后我可以在另一个对象的后面或内部获取对象。

我在 Autodesk Forge 查看器中尝试了这个概念，但没有成功。代码如下：

// Change this to:
// true to use original Three.js
// false to use Autodesk Forge Viewer API
var useThreeJS = true;

var container = $('div.canvas-wrap')[0];

container.addEventListener('mousedown', function (event) 
    if (useThreeJS) 
        var canvas = _viewer.impl.canvas;
        var containerWidth = canvas.clientWidth;
        var containerHeight = canvas.clientHeight;

        var camera = _viewer.getCamera();

        var mouse = mouse || new THREE.Vector3();
        var raycaster = raycaster || new THREE.Raycaster();

        mouse.x = 2 * (event.clientX / containerWidth) - 1;
        mouse.y = 1 - 2 * (event.clientY / containerHeight);
        mouse.unproject(camera);

        raycaster.set(camera.position, mouse.sub(camera.position).normalize());
        var intersects = raycaster.intersectObjects(objects);

        if (intersects.length == 1) 
            var obj = intersects[0].object;
            obj.material.color.setRGB(1.0 - i / intersects.length, 0, 0);
         else if (intersects.length > 1) 
            // Exclude the first which is the outer object (i == 0)
            for (var i = 1; i < intersects.length; i++) 
                var obj = intersects[i].object;
                obj.material.color.setRGB(1.0 - i / intersects.length, 0, 0);
            
        
     else 
        var vp = _viewer.impl.clientToViewport(event.canvasX, event.canvasY);
        var renderer = _viewer.impl.renderer();

        var dbId = renderer.idAtPixel(vp.x, vp.y);
        if (dbId) 
            console.debug("Selected Id: " + dbId);
            _viewer.select(dbId);
            _viewer.impl.invalidate(true);
        
    
, false);

我发现 Forge 查看器有 viewer.impl.renderer().idAtPixel 方法，该方法非常适合在拾取像素处获取元素。但是，我希望它做更多的事情，在拾取像素处选择所有元素（在下面或嵌套）。如何使用 Forge Viewer API 做到这一点？

【参考方案1】：

根据另一个post中吴钟的建议，这里是选择另一个元素下或内部的元素的最终解决方案。我创建了一个 Autodesk Forge 查看器扩展来轻松使用它。

///////////////////////////////////////////////////////////////////////////////
// InnerSelection viewer extension
// by Khoa Ho, December 2016
//
///////////////////////////////////////////////////////////////////////////////
AutodeskNamespace("Autodesk.ADN.Viewing.Extension");

Autodesk.ADN.Viewing.Extension.InnerSelection = function (viewer, options) 

    Autodesk.Viewing.Extension.call(this, viewer, options);

    var _self = this;

    var _container = viewer.canvas.parentElement;
    var _renderer = viewer.impl.renderer();
    var _instanceTree = viewer.model.getData().instanceTree;
    var _fragmentList = viewer.model.getFragmentList();
    var _eventSelectionChanged = false;
    var _viewport;
    var _outerDbId;

    _self.load = function () 

        _container.addEventListener('mousedown',
            onMouseDown);

        viewer.addEventListener(
            Autodesk.Viewing.SELECTION_CHANGED_EVENT,
            onItemSelected);

        console.log('Autodesk.ADN.Viewing.Extension.InnerSelection loaded');

        return true;
    ;

    _self.unload = function () 

        _container.removeEventListener('mousedown',
            onMouseDown);

        viewer.removeEventListener(
            Autodesk.Viewing.SELECTION_CHANGED_EVENT,
            onItemSelected);

        console.log('Autodesk.ADN.Viewing.Extension.InnerSelection unloaded');

        return true;
    ;

    function onMouseDown(e) 

        var viewport = viewer.impl.clientToViewport(e.canvasX, e.canvasY);
        _viewport = viewport; // Keep this viewport to use in onItemSelected()

        var dbId = _renderer.idAtPixel(viewport.x, viewport.y);

        if (_outerDbId == dbId) 
            _outerDbId = -1;

            // Deselect everything
            viewer.select();
         else 
            _outerDbId = dbId;

            // Hide outer element temporarily to allow picking its behind element
            viewer.hideById(dbId);

            _eventSelectionChanged = true;
        

        viewer.impl.sceneUpdated(true);
    

    function onItemSelected(e) 

        if (_eventSelectionChanged) 

            // Prevent self looping on selection
            _eventSelectionChanged = false;

            // Show outer element back
            viewer.show(_outerDbId);

            // Get inner element Id after the outer element
            // was just hidden on mouse down event
            var innerDbId = _renderer.idAtPixel(_viewport.x, _viewport.y);

            if (innerDbId > -1) 
                // Select the inner element when it is found
                viewer.select(innerDbId);

                console.debug("Selected inner Id: " + innerDbId);

             else if (_outerDbId > -1) 
                // Select the outer element if the inner element is not found
                viewer.select(_outerDbId);

                console.debug("Selected outer Id: " + _outerDbId);

            
        
    

;

Autodesk.ADN.Viewing.Extension.InnerSelection.prototype =
    Object.create(Autodesk.Viewing.Extension.prototype);

Autodesk.ADN.Viewing.Extension.InnerSelection.prototype.constructor =
    Autodesk.ADN.Viewing.Extension.InnerSelection;

Autodesk.Viewing.theExtensionManager.registerExtension(
    'Autodesk.ADN.Viewing.Extension.InnerSelection',
    Autodesk.ADN.Viewing.Extension.InnerSelection);

【参考方案2】：

我看到方法viewer.impl.renderer().idAtPixel 比viewer.impl.hitTestViewport 更好地选择鼠标选择元素。第一个可以通过hidden/ghost元素点击获取后面元素的objectId。而第二个不能。这是要测试的代码：

var container = $('div.canvas-wrap')[0];

container.addEventListener('mousedown', function (event) 

    var clickThroughHiddenElement = true;

    if (clickThroughHiddenElement) 
        var vp = _viewer.impl.clientToViewport(event.canvasX, event.canvasY);
        var renderer = _viewer.impl.renderer();

        var dbId = renderer.idAtPixel(vp.x, vp.y);
        if (!!dbId) 
            _viewer.select(dbId);
        
        console.debug("Selected Id: " + dbId);
     else 
        var screenPoint = 
            x: event.clientX,
            y: event.clientY
        ;
        var viewport = _viewer.navigation.getScreenViewport();
        var x = (screenPoint.x - viewport.left) / viewport.width;
        var y = (screenPoint.y - viewport.top) / viewport.height;
        // Normalize point
        x = x * 2.0 - 1.0;
        y = (1.0 - y) * 2.0 - 1.0;

        var vpVec = new THREE.Vector3(x, y, 1);
        var result = _viewer.impl.hitTestViewport(vpVec, false);
        if (!!result) 
            var dbId = result.dbId;
            _viewer.select(dbId);
            console.debug("Selected Id: " + dbId);
        
    

但是，它们不是我想要的，单击透明元素以获取后面的元素。如果用户选择透明元素，它将被选中。如果用户选择内部元素，它将忽略外部透明元素来选择内部元素。

我检查了 Forge 查看器使用带有元素边界框的 THREE.Raycaster 来检测鼠标单击时的交叉点。看来我的问题在 Forge 查看器中是可行的，就像在我的 Three.js demo 中一样。

【参考方案3】：

截至目前（12 月 16 日），当您使用鼠标单击选择时，查看器将不会忽略透明元素，因此即使它是透明的，它也会选择一个元素。下面是我用来跟踪光标下的内容的代码，也许会有用。

// use jQuery to bind a mouve move event
$(_viewer.container).bind("mousemove", onMouseMove);

function onMouseMove(e) 
    var screenPoint = 
       x: event.clientX,
       y: event.clientY
    ;
    var n = normalize(screenPoint);
    var dbId = /*_viewer.utilities.getHitPoint*/ getHitDbId(n.x, n.y);
    //
    // use the dbId somehow...
    //


// This is a built-in method getHitPoint, but the original returns
// the hit point, so this modified version returns the dbId
function getHitDbId()
    y = 1.0 - y;
    x = x * 2.0 - 1.0;
    y = y * 2.0 - 1.0;
    var vpVec = new THREE.Vector3(x, y, 1);
    var result = _viewer.impl.hitTestViewport(vpVec, false);

    //return result ? result.intersectPoint : null; // original implementation
    return result ? result.dbId : null;


function normalize(screenPoint) 
    var viewport = _viewer.navigation.getScreenViewport();
    var n = 
       x: (screenPoint.x - viewport.left) / viewport.width,
       y: (screenPoint.y - viewport.top) / viewport.height
    ;
    return n;

【讨论】：

viewer.impl.hitTestViewport 无法选择隐藏/幽灵元素后面的元素。 viewer.impl.renderer().idAtPixel 效果更好。