[Silverlight动画]转向行为 - 躲避行为

 

躲避就是追捕的反行为。就像追捕类似于寻找，躲避类似于避开。

本质上讲，是预测出机车将要去到的位置并远离它。在这里所有的原则都和追捕相同。实际上，就连实现都几乎一模一样，除了最后一行用避开代替寻找：

                public void evade(Vehicle target)
        {
            double lookAheadTime = position.dist(target.position) / _maxSpeed;
            Vector2D predictedTarget = target.position.add(target.velocity.multiply(lookAheadTime));
            flee(predictedTarget);
        }

直接把追捕和躲避放一起测试：

<UserControl
	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:Steer" xmlns:ed="http://schemas.microsoft.com/expression/2010/drawing"
	mc:Ignorable="d"
	x:Class="Steer.PursueEvadeTest"
	d:DesignWidth="640" d:DesignHeight="480">

	<Grid x:Name="LayoutRoot" Background="White">
		<local:SteeredVehicle x:Name="myPursuer" HorizontalAlignment="Left" Height="40" VerticalAlignment="Top" Width="40" RenderTransformOrigin="0.5,0.5">
			<ed:RegularPolygon Fill="Blue" Height="40" InnerRadius="1" PointCount="3" Stretch="Fill" Stroke="Black" UseLayoutRounding="False" Width="40" RenderTransformOrigin="0.5,0.5" StrokeThickness="0">
				<ed:RegularPolygon.RenderTransform>
					<CompositeTransform Rotation="90"/>
				</ed:RegularPolygon.RenderTransform>
			</ed:RegularPolygon>
		</local:SteeredVehicle>
		<local:SteeredVehicle x:Name="myEvader" HorizontalAlignment="Left" Height="40" VerticalAlignment="Top" Width="40" RenderTransformOrigin="0.5,0.5">
			<ed:RegularPolygon Fill="#FFFD00FF" Height="40" InnerRadius="1" PointCount="5" Stretch="Fill" Stroke="Black" StrokeThickness="0" UseLayoutRounding="False" Width="40"/>
		</local:SteeredVehicle>

	</Grid>
</UserControl>

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Steer
{
	public partial class PursueEvadeTest : UserControl
	{
		public PursueEvadeTest()
		{
			// Required to initialize variables
			InitializeComponent();
            Loaded += new RoutedEventHandler(PursueEvadeTest_Loaded);
		}

        void PursueEvadeTest_Loaded(object sender, RoutedEventArgs e)
        {
            myPursuer.position = new Vector2D(200, 200);
            myPursuer.edgeBehavior = Vehicle.BOUNCE;

            myEvader.position = new Vector2D(400, 300);
            myEvader.edgeBehavior = Vehicle.BOUNCE;

            CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);
        }

        void CompositionTarget_Rendering(object sender, EventArgs e)
        {
            myPursuer.pursue(myEvader);
            myEvader.evade(myPursuer);

            myPursuer.update();
            myEvader.update();
        }
	}
}