WPF翻转动画

在WPF中要翻转对象，估计是得用三维变换，所以我用到了AxisAngleRotation3D，让图形绕着Z轴来旋转。

先看看效果。

WPF翻转动画

是的，就是这样的效果，在XAML中，由于涉及三维图形，我先做了两个用户控件，作为正面和背面，然后让它旋转。

设计完用户控件后，就在主窗口上放一个Viewport3D控件，这个是必须的，它是三维模型的容器，如果不用就不知道怎么弄出三维图形来了。具体请看下面的XAML：

<Window x:Class="翻转.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="420" Width="650"
xmlns:local="clr-namespace:翻转"
WindowStyle="None"
ResizeMode="NoResize"
AllowsTransparency="True"
Background="Transparent"
WindowStartupLocation="CenterScreen">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="auto"/>
</Grid.RowDefinitions>
<Viewport3D Grid.Row="0" Margin="3">
<Viewport3D.Camera>
<PerspectiveCamera Position="0 0 800" LookDirection="0 0 -1" NearPlaneDistance="100"/>
</Viewport3D.Camera>
<Viewport3D.Children>
<ContainerUIElement3D>
<Viewport2DVisual3D>
<Viewport2DVisual3D.Geometry>
<MeshGeometry3D Positions="-200 150 0 -200 -150 0 200 -150 0 200 150 0" TriangleIndices="0 1 2 0 2 3" TextureCoordinates="0 0 0 1 1 1 1 0"/>
</Viewport2DVisual3D.Geometry>
<Viewport2DVisual3D.Material>
<DiffuseMaterial Viewport2DVisual3D.IsVisualHostMaterial="True"/>
</Viewport2DVisual3D.Material>
<Viewport2DVisual3D.Visual>
<local:UcSample1 Width="400" Height="300"/>
</Viewport2DVisual3D.Visual>
</Viewport2DVisual3D>
<Viewport2DVisual3D>
<Viewport2DVisual3D.Geometry>
<MeshGeometry3D Positions="200 150 0 200 -150 0 -200 -150 0 -200 150 0" TriangleIndices="0 1 2 0 2 3" TextureCoordinates="0 0 0 1 1 1 1 0"/>
</Viewport2DVisual3D.Geometry>
<Viewport2DVisual3D.Material>
<DiffuseMaterial Viewport2DVisual3D.IsVisualHostMaterial="True"/>
</Viewport2DVisual3D.Material>
<Viewport2DVisual3D.Visual>
<local:UcSample2 Width="400" Height="300"/>
</Viewport2DVisual3D.Visual>
</Viewport2DVisual3D>
<ContainerUIElement3D.Transform>
<RotateTransform3D CenterX="0.5" CenterY="0.5" CenterZ="0.5">
<RotateTransform3D.Rotation>
<AxisAngleRotation3D x:Name="axr" Angle="0" Axis="0 1 0"/>
</RotateTransform3D.Rotation>
</RotateTransform3D>
</ContainerUIElement3D.Transform>
</ContainerUIElement3D>
<ModelVisual3D>
<ModelVisual3D.Content>
<DirectionalLight Color="Transparent"/>
</ModelVisual3D.Content>
</ModelVisual3D>
</Viewport3D.Children>
</Viewport3D>
<StackPanel Grid.Row="1" Margin="0,5,0,6" Orientation="Horizontal" HorizontalAlignment="Center">
<Button Padding="25,5" Content="向前" Click="OnClick"/>
<Button Padding="25,5" Content="向后" Click="OnClick" Margin="12,0,0,0"/>
<Button Padding="25,5" Content="关闭" Click="OnClick" Margin="12,0,0,0"/>
</StackPanel>
</Grid>
</Window>

里面还有几个按钮，我是通过单击按钮来控制动画的，所以，后面还要写必要的处理代码，生成动画。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Media.Media3D;
using System.Windows.Media.Animation;
namespace 翻转
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void OnClick(object sender, RoutedEventArgs e)
{
Button btn = e.OriginalSource as Button;
if (btn != null)
{
string s = btn.Content.ToString();
if (s == "关闭")
{
this.Close();
}
DoubleAnimation da = new DoubleAnimation();
da.Duration = new Duration(TimeSpan.FromSeconds(1));
if (s == "向前")
{
da.To = 0d;
}
else if (s == "向后")
{
da.To = 180d;
}
this.axr.BeginAnimation(AxisAngleRotation3D.AngleProperty, da);
}
}
}
}

当图形绕Z轴转0度，就表示是正面，如果为180度，就转到反面。我们在声明Viewport2DVisual3D.Geometry的坐标模型，即三角型叠加模型，要注意点逆时针方向顺序来定义，如果弄反了，那么图形就跑到模型的背面去了。因此，正面图形和背面图形的点的方向是刚好相反的。

三维的东西不太好解释，所以我稍后把代码上传，以供参考。

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