WPF实现绘制3D图形的示例代码

WPF的3D功能可以在不编写任何c#代码的情况下进行绘制,只需要使用xaml即可完成3D图形的渲染。本文主要讲述了WPF-3D中的关键概念, 以及常用到的命中测试、2d控件如何在3D对象中进行渲染,除此之外,还演示了如何导入外部3D模型。

 

关键概念

视口

视口指的是图像要展示在哪里,可以理解为展示图形的舞台。在WPF中视口使用Viewport3D标签表示。

相机

如果把视口比作舞台,那相机就可以理解为观众的眼睛,不同的眼睛位置会看到不同的角度。

<Viewport3D>
  <!--相机-->
  <Viewport3D.Camera>
      <!--透视相机-->
      <PerspectiveCamera Position="8,5,10"
                         LookDirection="-7,-2,-10"
                         FarPlaneDistance="40"
                         NearPlaneDistance="10"
                         FieldOfView="60"> 
          <PerspectiveCamera.Transform>
              <RotateTransform3D CenterX="1.5" CenterY="1" CenterZ="0.5">
                  <RotateTransform3D.Rotation>
                      <AxisAngleRotation3D Angle="45" Axis="0,1,0"/>
                  </RotateTransform3D.Rotation>
              </RotateTransform3D>
          </PerspectiveCamera.Transform>
      </PerspectiveCamera>
      <!--正交相机,用法类似-->
      <!--<OrthographicCamera/>-->
</Viewport3D.Camera>

光源

没有光源也就看不到3D对象

<!--光线-->
<ModelVisual3D>
  <ModelVisual3D.Content>
      <Model3DGroup>
          <!--散射光线-->
          <AmbientLight Color="#FFF"/>
          <!--平行光-->
          <!--<DirectionalLight Color="#FFF" Direction="0,-1,0"/>-->
          <!--点光源-->
          <!--<PointLight Position="0,0,0"/>-->
          <!--锥形辐射光:手电筒-->
          <!--<SpotLight Position="0,0,0" Direction="0,0,-3"/>-->
      </Model3DGroup>
  </ModelVisual3D.Content>
</ModelVisual3D>

材质

3D几何对象只是将轮廓定义出来,表面是没有定义的,所以需要使用材质来展现出不同的物体表面。也可以理解为3D几何对象只是勾勒出物体的轮廓,而材质则是上颜色。

<ModelUIElement3D >
  <ModelUIElement3D.Model>
      <GeometryModel3D>
          <!--材质-->
          <GeometryModel3D.Material>
              <!--散射材质-->
              <DiffuseMaterial Brush="Blue"/>
              <!--镜面材质-->
              <!--<SpecularMaterial SpecularPower="1" Brush="Blue"/>-->
              <!--自发光材质-->
              <!--<EmissiveMaterial Color="Green" />-->
          </GeometryModel3D.Material>
          <GeometryModel3D.Geometry>
              <MeshGeometry3D Positions="0,0,1 0,2,1 3,2,1 3,0,1
                                         0,0,0 0,2,0 3,2,0 3,0,0"
                              TriangleIndices="2,3,7 7,6,2 1,5,4 0,1,4"/>
          </GeometryModel3D.Geometry>
      </GeometryModel3D>
  </ModelUIElement3D.Model>
</ModelUIElement3D>

3D对象

3D对象则是具体的对象,在WPF中视口使用<ModelUIElement3D>标签表示。在WPF中,图形是以三角面片作为最基本的展示单元,因为三角形是最稳定的即三个点可以确定出唯一的一个平面,任何复杂的图形都是由多个三角面片组成的。在给TriangleIndices属性赋值时,一定注意三个点的顺序。

 

命中测试(鼠标交互)

想要使用鼠标点击得到某个图形,可以在具体的某个3D对象中,增加MouseLeftButtonDown事件

<ModelUIElement3D MouseLeftButtonDown="ModelUIElement3D_MouseLeftButtonDown">事件中可以进行改变颜色等操作

private void ModelUIElement3D_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
  ModelUIElement3D mui3d = sender as ModelUIElement3D;
  var model = mui3d.Model as GeometryModel3D;
  (model.Material as DiffuseMaterial).Brush = Brushes.Orange;
}

如果有很多3D对象,在每个具体的对象上面增加事件会很麻烦,也可以直接在Viewport3D中增加事件

<Viewport3D MouseLeftButtonDown="Viewport3D_MouseLeftButtonDown">在时间中急性转换处理

private void Viewport3D_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
  Viewport3D viewport3D=sender as Viewport3D; 
  Point location=e.GetPosition(viewport3D);
  HitTestResult hitTestResult=VisualTreeHelper.HitTest(viewport3D, location);
  if (hitTestResult != null)
  {
      ...//具体操作
  }
}

 

3D对象中2D控件渲染

如果要在3D对象中增加控件,可以使用Viewport2DVisual3D标签,实现如下图所示的效果。

<Viewport3D>
<Viewport2DVisual3D>
  <Viewport2DVisual3D.Geometry>
      <MeshGeometry3D Positions="0,0,1 0,2,1 3,2,1 3,0,1
                     0,0,0 0,2,0 3,2,0 3,0,0"
          TriangleIndices="0,2,1 0,3,2 6,4,5 6,7,4"
          TextureCoordinates="0,1 0,0 1,0 1,1"/>
      <!--TextureCoordinates:表示的二维平面坐标,原点:左上角-->
  </Viewport2DVisual3D.Geometry>

  <Viewport2DVisual3D.Material>
      <DiffuseMaterial Viewport2DVisual3D.IsVisualHostMaterial="True" Brush="White"/>
  </Viewport2DVisual3D.Material>
  <Viewport2DVisual3D.Visual>
  <Border BorderThickness="1" BorderBrush="Yellow">
      <StackPanel>
          <TextBlock Text="Hello World" Foreground="Green" />
          <Button Content="Button" Click="Button_Click"/>
      </StackPanel>
  </Border>
  </Viewport2DVisual3D.Visual>
</Viewport2DVisual3D>
<Viewport3D>

 

外部导入3D模型

在wpf中绘制3D模型还是非常麻烦的,在实际工作中用的比较多的是从外部导入已有的3d模型。推荐一个比较好的第三方库HelixToolKit

<Window x:Class="WpfApp2.MainWindow"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      xmlns:local="clr-namespace:WpfApp2"
      xmlns:helix="http://helix-toolkit.org/wpf"
      mc:Ignorable="d"
      Title="MainWindow" Height="450" Width="800">
  <Grid>
      <helix:HelixViewport3D  Name="viewPort3d"
                              ShowViewCube="True"
          ViewCubeBackText="后" ViewCubeFrontText="前" ViewCubeHeight="100" ViewCubeWidth="100" 
          ViewCubeVerticalPosition="Bottom"
          ViewCubeHorizontalPosition="Right"
          
          ShowCoordinateSystem="True"
          CoordinateSystemLabelForeground="Red"
          CoordinateSystemHorizontalPosition="Left"
          CoordinateSystemVerticalPosition="Bottom"
          
          ShowFrameRate="True"
          
          IsViewCubeEdgeClicksEnabled="False">


          <helix:HelixViewport3D.Camera>
              <PerspectiveCamera FieldOfView="45"  
                                 LookDirection="0,0,-414.387754871885" 
                                 FarPlaneDistance="30000"
                                 NearPlaneDistance="0.1" 
                                 Position="9.9475983006414E-14,91.037123633789,414.387754871885" 
                                 UpDirection="0,1,0"/>
          </helix:HelixViewport3D.Camera>

          <helix:HelixViewport3D.Background>
              <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                  <GradientStop Color="#444" Offset="0"/>
                  <GradientStop Color="#EEE" Offset="1"/>
              </LinearGradientBrush>
          </helix:HelixViewport3D.Background>
          <helix:GridLinesVisual3D Width="16000" Length="16000" Thickness="2" MinorDistance="500" MajorDistance="500" Fill="Gray" />

          <!--很重要,没有灯光场景是黑的-->
          <helix:DefaultLights/>

          <ModelVisual3D x:Name="model"></ModelVisual3D>

      </helix:HelixViewport3D>
  </Grid>
</Window>
namespace WpfApp2
{
  public partial class MainWindow : Window
  {
      List<string> modelPaths = new List<string>();
      string basePath = AppDomain.CurrentDomain.BaseDirectory + "\\ModelFiles\\";
      public MainWindow()
      {
          InitializeComponent();
          modelPaths.Add("IRB4600_20kg-250_LINK1_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK2_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK3_CAD_rev005.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK4_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK5_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK6_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_LINK3_CAD_rev04.stl");
          modelPaths.Add("IRB4600_20kg-250_CABLES_LINK1_rev03.stl");
          modelPaths.Add("IRB4600_20kg-250_CABLES_LINK2_rev03.stl");
          modelPaths.Add("IRB4600_20kg-250_CABLES_LINK3_rev03.stl");
          modelPaths.Add("IRB4600_20kg-250_BASE_CAD_rev04.stl");

          this.Loaded += MainWindow_Loaded;

          viewPort3d.RotateGesture = new MouseGesture(MouseAction.RightClick);
          viewPort3d.PanGesture = new MouseGesture(MouseAction.LeftClick);
      }
      private void MainWindow_Loaded(object sender, RoutedEventArgs e)
      {
          viewPort3d.Camera.LookDirection = new Vector3D(2038, -5200, -2930);
          viewPort3d.Camera.UpDirection = new Vector3D(-0.145, 0.372, 0.917);
          viewPort3d.Camera.Position = new Point3D(-1571, 4801, 3774);

          this.model.Content = InitializeModels(this.modelPaths);
      }

      private Model3DGroup InitializeModels(List<string> modelsNames)
      {
          Model3DGroup group = new Model3DGroup();
          try
          {
              ModelImporter import = new ModelImporter();

              foreach (string modelName in modelsNames)
              {
                  var materialGroup = new MaterialGroup();
                  Color mainColor = Colors.White;
                  //EmissiveMaterial emissMat = new EmissiveMaterial(new SolidColorBrush(mainColor));
                  DiffuseMaterial diffMat = new DiffuseMaterial(new SolidColorBrush(mainColor));
                  //SpecularMaterial specMat = new SpecularMaterial(new SolidColorBrush(mainColor), 2000);
                  //materialGroup.Children.Add(emissMat);
                  materialGroup.Children.Add(diffMat);
                  //materialGroup.Children.Add(specMat);

                  var link = import.Load(basePath + modelName);
                  GeometryModel3D model = link.Children[0] as GeometryModel3D;
                  model.Material = materialGroup;
                  model.BackMaterial = materialGroup;

                  group.Children.Add(link);
              }
          }
          catch (Exception e)
          {
              MessageBox.Show("未知异常:" + e.StackTrace);
          }
          return group;
      }
  }
}

HelixToolKit使用文档

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