wpf3d 矩形 HitTest

Question

我有一个包含驻留在 Viewport3D 中的 3D 对象的应用程序，我希望用户能够通过在屏幕上拖动一个矩形来选择它们。

我尝试在 Viewport3D 上应用 GeometryHitTestParameters(带有矩形几何)以获得结果，但我收到一个异常，告诉我它不支持 Viewport3D。仅支持 PointHitTestParameters。

有没有人知道任何优雅的方法来做到这一点，除了自己计算它(例如 - 将所有 3D 对象投影到 2D 并与矩形进行手动几何交集)？

Answer 1

我怀疑有比遍历选定的矩形点更好的方法:

    private void view_PreviewMouseDown(object sender, MouseButtonEventArgs e) {
        const double offset = 3.0; // I will test in a square 7x7
        var mouse = e.GetPosition(this);
        var items = new HashSet<Model3D>();
        for (double x = mouse.X - offset; x <= mouse.X + offset; x++)
            for (double y = mouse.Y - offset; y <= mouse.Y + offset; y++) {
                PointHitTestParameters pointparams = new PointHitTestParameters(new Point(x, y));
                Model3D result = null;
                VisualTreeHelper.HitTest(view, null, rawresult => {
                    var rayResult = rawresult as RayMeshGeometry3DHitTestResult;
                    if (rayResult != null)
                        items.Add(rayResult.ModelHit);
                    return HitTestResultBehavior.Continue;
                }, pointparams);
            }
        // temporary ListBox to show items
        list.ItemsSource = items.Select(item => item as GeometryModel3D == null ? null : (item as GeometryModel3D).Material as object);
    }

见 MSDN How to: Hit Test in a Viewport3D