WPF 3D - Detirmine是否ModelVisual3D被修剪它里面的Viewport3D [英] WPF 3D - Detirmine whether a ModelVisual3D is being clipped inside it's Viewport3D

问题描述

我有一个 Viewport3D 里面的一个立方体的渲染，我需要知道的方式，找出是否所有的立方体是对用户可见。

I have a cube rendering inside a Viewport3D and i need to know a way to find out whether ALL of the cube is visible to the user.

编辑：只是要清楚，..我不是在谈论剪辑，因为近/远平面的距离在这里。我的意思是立方体是高或宽，以适应视摄像头领域。

任何帮助将是大量AP preciated！

Any help would be massively appreciated!

在此先感谢。

推荐答案

我不能提供一个解决方案，但我可以，也许，你指明正确的方向。

I can't offer a solution but I can, perhaps, point you in the right direction.

您需要什么弄个是在视图平面立方体的2D投影的程度。然后，您可以做的最小和最大X'放一个简单的检查; Y值看整个魔方是否可见。

What you need to get hold of is the extent of the 2D projection of the cube on the view plane. You can then do a simple check on the min and max X & Y values to see whether the whole of the cube is visible.

添加一个宽容的因素在某种程度上将采取任何舍入误差的照顾。

Adding a tolerance factor to the extent will take care of any rounding errors.

编辑：我刚刚做了谷歌搜索2D投影WPF这链接上来。它看起来像它解决了你想要的。

I have just done a Google search for "2D projection WPF" and this link came up. It looks like it addresses what you want.

进一步编辑：我从这里上面的链接复制的code中的相关章节

FURTHER I've copied the relevant section of code from the above link here.

public static Rect Get2DBoundingBox(ModelVisual3D mv3d)
{
    bool bOK;

    Matrix3D m = MathUtils.TryWorldToViewportTransform(vpv, out bOK);

    bool bFirst = true;    
    Rect r = new Rect();

    if (mv3d.Content is GeometryModel3D)
    {
        GeometryModel3D gm3d = (GeometryModel3D) mv3d.Content;

        if (gm3d.Geometry is MeshGeometry3D)
        {
            MeshGeometry3D mg3d = (MeshGeometry3D)gm3d.Geometry;

            foreach (Point3D p3d in mg3d.Positions)
            {
                Point3D pb = m.Transform(p3d);
                Point p2d = new Point(pb.X, pb.Y);
                if (bFirst)
                {
                    r = new Rect(p2d, new Size(1, 1));
                    bFirst = false;
                }
                else
                {
                    r.Union(p2d);
                }
            }
        }
    }

    return r;
}

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