Question

我的应用程序包含驻留在Viewport3D中的3D对象，我希望用户能够通过在屏幕上拖动矩形来选择它们。

我尝试在Viewport3D上应用GeometryHitTestParameters（带有矩形几何体）以获得结果，但是我得到一个异常，告诉我它没有用于Viewport3D。只支持PointHitTestParameters。

有没有人知道任何优雅的方法，除了自己计算（例如 - 将所有3D对象投影到2D并用矩形做手动几何交叉）？

Answer 1

我怀疑除了迭代选定的矩形点之外还有更好的方法：

    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);
    }

请参阅MSDN How to: Hit Test in a Viewport3D

wpf3d矩形命中测试

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