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.Diagnostics;

namespace Geometry
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        // veriables
        private Vector v1 = new Vector(0, 0);       //speed
        private TimeSpan prevTime = TimeSpan.Zero;  //time interval
        private Point point = new Point(0, 0);      //objct posion
        private Point pMouse = new Point(0, 0);     //layout posion
        private Line line = new Line();             //line
        private Stopwatch stopwatch = new Stopwatch();// timer
        private void Windown_Load(object sender, RoutedEventArgs e)
        {
            //add RenderTransform
            this.moveObj.RenderTransform = new TranslateTransform();
            //counter start
            stopwatch.Start();
            //对象提供了创建基于每帧回调的自定义动画的功能。
            //每帧渲染之前触发CompositionTarget的Rendering事件。
            //想要在每帧动画渲染前做一些处理，可以调用实现此事件。
            CompositionTarget.Rendering += new EventHandler(CompositionTarget_render);
            //line
            line.StrokeThickness = 2;
            line.Stroke = System.Windows.Media.Brushes.LightBlue;
            layout.Children.Add(line);
        }
        private void Window_MouseLeftButtonUp(object sender,MouseButtonEventArgs e)
        {
            //get the object position
            point = e.GetPosition(moveObj);
            point.Offset(-moveObj.ActualWidth / 2, -moveObj.ActualHeight / 2);
            pMouse=e.GetPosition(layout);
        }
        private void CompositionTarget_render(object sender, EventArgs e)
        {
            //获取当前实例测量得出的总运行时间
            TimeSpan currentTime = this.stopwatch.Elapsed;
            double t = (currentTime - this.prevTime).TotalSeconds;
            this.prevTime = currentTime;
            Vector fPush = new Vector(point.X, point.Y);
            double eta = 100;
            double d = moveObj.Width;
            double rho = 1;
            double m = (Math.PI * d * d * d * rho / 6);
            fPush = d * d * d * fPush;
            Vector vDiff = ((fPush - 3 * Math.PI * eta * v1 * d) / m) * t;
            Vector s = v1 * t + vDiff * t / 2;

            //trajectory
            TranslateTransform translate = (TranslateTransform)moveObj.RenderTransform;
            translate.X += s.X;
            translate.Y += s.Y;
            //new position
            point.X -= s.X;
            point.Y -= s.Y;
            Vector v2 = vDiff + v1;
            v1 = v2;
            //line
            line.X1 = pMouse.X;
            line.Y1 = pMouse.Y;
            line.X2 = pMouse.X - point.X;
            line.Y2 = pMouse.Y - point.Y;
        }
    }
}

<Window x:Class="Geometry.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" Loaded="Windown_Load" MouseLeftButtonUp="Window_MouseLeftButtonUp">
    <Grid Name="layout">
        <Viewport3D Width="auto" Margin="0">
            <Viewport3D.Camera>
                <PerspectiveCamera Position="-1.5 2 4" LookDirection="0.4 -0.5 -1"/>
            </Viewport3D.Camera>
            <ModelVisual3D>
                <ModelVisual3D.Content>
                    <Model3DGroup>
                        <GeometryModel3D>
                            <GeometryModel3D.Geometry>
                                <MeshGeometry3D Positions=
                                                "
                                                -1,0, 0 
                                                0 ,0,-1 
                                                1 ,0, 0 
                                                0 ,0, 1 
                                                0 ,1, 0"
                                                TriangleIndices="
                                                0 1 2 
                                                2 3 0
                                                1 0 4
                                                0 3 4
                                                3 2 4
                                                2 1 4
                                                " />
                            </GeometryModel3D.Geometry>
                            <GeometryModel3D.Material>
                                <DiffuseMaterial>
                                    <DiffuseMaterial.Brush>
                                        <SolidColorBrush Color="Green" Opacity="0.5"/>
                                    </DiffuseMaterial.Brush>
                                </DiffuseMaterial>
                            </GeometryModel3D.Material>
                            <GeometryModel3D.BackMaterial>
                                <DiffuseMaterial>
                                    <DiffuseMaterial.Brush>
                                        <SolidColorBrush Color="Red" Opacity="0.5"/>
                                    </DiffuseMaterial.Brush>
                                </DiffuseMaterial>
                            </GeometryModel3D.BackMaterial>

                            <GeometryModel3D.Transform>
                                <RotateTransform3D>
                                    <RotateTransform3D.Rotation>
                                        <AxisAngleRotation3D x:Name="myAngleRotation" Axis="0,1,0" Angle="0"/>
                                    </RotateTransform3D.Rotation>
                                </RotateTransform3D>
                            </GeometryModel3D.Transform>
                        </GeometryModel3D>
                        <DirectionalLight Direction="1 0 0" Color="White"/>
                    </Model3DGroup>
                </ModelVisual3D.Content>
            </ModelVisual3D>
            <!--add animation play-->
            <Viewport3D.Triggers>
                <EventTrigger RoutedEvent="Viewport3D.Loaded">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation 
                                    Storyboard.TargetName="myAngleRotation"
                                    Storyboard.TargetProperty="Angle"
                                    From="0" To="360" Duration="0:0:10"
                                    RepeatBehavior="Forever" />
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Viewport3D.Triggers>
        </Viewport3D>
        <Image Name="moveObj" Width="80" Height="80" Source="F:\MiloLu\2015\vs\C#\ico\favicon-20190830044057967.ico"/>
    </Grid>
</Window>