需要帮助编写2D和3D之间的转换方法（Point3DToPoint和PointAndZToPoint3D） [英] Need help writing conversion methods between 2D and 3D (Point3DToPoint and PointAndZToPoint3D)

问题描述

我是新来的WPF 3D，所以我可能只是缺少明显的东西，但我怎么从3D转换为2D和（对于给定ž位置）从2D到3D？

I'm new to WPF 3D, so I may just be missing something obvious, but how do I convert from 3D to 2D and (for a given z location) from 2D to 3D?

具体而言，我需要两个转换方法：

Specifically, I need two conversion methods:

• Point3DToPoint - 如果我有一个（X，Y，Z）在3D世界坐标，我怎么确定（X，Y）的投射二维表面上的坐标。方法签名：公共点Point3DToPoint（三维点三维点）

• Point3DToPoint - If I have an (x, y, z) coordinate in the 3D world, how do I determine the (x, y) coordinate on the projected 2D surface. Method signature: public Point Point3DToPoint(Point3D point3D)

PointAndZToPoint3D - 如果我有一个（X，Y）的投射二维表面的和协调的3D世界中AZ的位置，我怎么确定（X，Y，Z）在3D世界坐标？方法签名：公共三维点PointAndZToPoint3D（点对点，双Z）

PointAndZToPoint3D - If I have an (x, y) coordinate on the projected 2D surface and a z location in the 3D world, how do I determine the (x, y, z) coordinate in the 3D world? Method signature: public Point3D PointAndZToPoint3D(Point point, double z)

我想在 2D坐标可以从 Viewport3D 的左上角测量的位置和三维坐标是位置相对原点（0，0，0）的3D世界。

I'd like the 2D coordinate to be the location measured from the upper-left corner of Viewport3D and the 3D coordinate to be the location relative to the origin (0, 0, 0) of the 3D world.

注1：我发现这个<一href="http://stackoverflow.com/questions/724219/how-to-convert-a-3d-point-into-2d-perspective-projection">related问题，但它只是解决了从3D到2D的转换（而不是相反），我不知道，如果答案是最新的最新的。

Note 1: I found this related question, but it only addresses conversion from 3D to 2D (not the reverse), and I'm not sure if the answers are up-to-date.

注2：我目前使用.NET 3.5，但如果有在.NET 4.0中的改进将帮助我，请让我知道

Note 2: I'm currently using .NET 3.5, but if there are improvements in .NET 4.0 that would help me, please let me know.

推荐答案

查尔斯Petzold的3D库，可下载的这里下」，包含一个类 ViewportInfo 这两个静态方法：

Charles Petzold's 3D Library, which can be downloaded here under "The Petzold.Media3D library", contains a class ViewportInfo with these two static methods:

• 公共静态点Point3DToPoint2D（Viewport3D视口，三维点点）

公共静态布尔Point2DToPoint3D（Viewport3D视，点，PTIN，出LineRange范围）

Point2DToPoint3D 不是精确匹配PointAndZToPoint3D（），因为它返回（通过退出参数）一个 LineRange ，而不是一个特定的点，但它只是恰巧， LineRange 有一个方法 PointFromZ（双zValue），它提供了那里的射线相交由Z = zValue 。

Point2DToPoint3D isn't an exact match for PointAndZToPoint3D() because it returns (via an out parameter) a LineRange rather than a specific point, but it just so happens that LineRange has a method PointFromZ(double zValue), which provides the point where the ray intersects the plane defined by z = zValue.

code样品：<​​/ STRONG>

Code Sample:

using System.Windows;
using System.Windows.Input;
using Petzold.Media3D;

namespace _3DTester
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        /* This MouseDown event handler prints:
          (1) the current position of the mouse
          (2) the 3D mouse location on the ground plane (z = 0)
          (3) the 2D mouse location converted from the 3D location */

        private void Window_MouseDown(object sender, MouseEventArgs e)
        {
            var range = new LineRange();
            var isValid = ViewportInfo.Point2DtoPoint3D(Viewport, e.GetPosition(Viewport), out range);
            if (!isValid)
                MouseLabel.Content = "(no data)";
            else
            {
                var point3D = range.PointFromZ(0);
                var point = ViewportInfo.Point3DtoPoint2D(Viewport, point3D);
                MouseLabel.Content = e.GetPosition(Viewport) + "\n" + point3D + "\n" + point;
            }
        }
    }
}

XAML code

<Window
    x:Class="_3DTester.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1"
    Height="300"
    Width="300"
    MouseDown="Window_MouseDown">
    <Grid>
        <Viewport3D Name="Viewport">
            <Viewport3D.Camera>
                <PerspectiveCamera
                    Position="0,0,30"
                    LookDirection="0,0,-1" 
                    UpDirection="0,1,0" />
            </Viewport3D.Camera>
            <ModelVisual3D>
                <ModelVisual3D.Content>
                    <Model3DGroup>
                        <DirectionalLight Color="White" Direction="1,-1,-1" />
                        <GeometryModel3D>
                            <GeometryModel3D.Geometry>
                                <MeshGeometry3D
                                    Positions="0,0,10 -5,-5,0 -5,5,0 5,5,0 5,-5,0"
                                    TriangleIndices="2 1 0  2 0 3  4 3 0  1 4 0" />
                            </GeometryModel3D.Geometry>
                            <GeometryModel3D.Material>
                                <DiffuseMaterial Brush="Red" />
                            </GeometryModel3D.Material>
                        </GeometryModel3D>
                    </Model3DGroup>
                </ModelVisual3D.Content>
            </ModelVisual3D>
        </Viewport3D>
        <Label Name="MouseLabel" Content="(no data)" />
    </Grid>
</Window>

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