如何：向三维对象的正面和背面应用材料
下面的示例演示如何将 Material 应用于三维对象的正面和背面，并对对象进行动画处理，以显示对象的两面。 GeometryModel3D 的 Material 属性用于在对象的正面应用一个红色的 Brush，GeometryModel3D 的 BackMaterial 属性用于在对象的背面应用一个蓝色的 Brush。 下面的代码显示了材料在对象上的应用：
<!-- This material is applied to the front of the 3D object (red side).-->
<GeometryModel3D.Material>
<MaterialGroup>
<DiffuseMaterial>
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Red"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</MaterialGroup>
</GeometryModel3D.Material>
<!-- This material is applied to the back of the 3D object (blue side).-->
<GeometryModel3D.BackMaterial>
<MaterialGroup>
<DiffuseMaterial>
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Blue"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</MaterialGroup>
</GeometryModel3D.BackMaterial>
示例
下面的代码显示了完整的示例。
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
<DockPanel>
<Viewbox>
<Canvas Width="321" Height="201">
<!-- The Viewport3D provides a rendering surface for 3-D visual content. -->
<Viewport3D Name="MyAnimatedObject"
ClipToBounds="True" Width="150" Height="150"
Canvas.Left="0" Canvas.Top="10">
<!-- Defines the camera used to view the 3D object. -->
<Viewport3D.Camera>
<PerspectiveCamera x:Name="myPerspectiveCamera" Position="0,0,2" LookDirection="0,0,-1"
FieldOfView="60" />
</Viewport3D.Camera>
<!-- The ModelVisual3D children contain the 3D models -->
<Viewport3D.Children>
<!-- Two ModelVisual3D define the lights cast in the scene. Without light, the
3D object cannot be seen. Also, the direction of the lights affect shadowing. -->
<ModelVisual3D>
<ModelVisual3D.Content>
<DirectionalLight Color="#FFFFFF" Direction="-0.612372,-0.5,-0.612372" />
</ModelVisual3D.Content>
</ModelVisual3D>
<ModelVisual3D>
<ModelVisual3D.Content>
<DirectionalLight Color="#FFFFFF" Direction="0.612372,-0.5,-0.612372" />
</ModelVisual3D.Content>
</ModelVisual3D>
<ModelVisual3D>
<ModelVisual3D.Content>
<GeometryModel3D>
<!-- The geometry specifes the shape of the 3D plane. In this case, a flat sheet is created. -->
<GeometryModel3D.Geometry>
<MeshGeometry3D
TriangleIndices="0,1,2 3,4,5 "
Normals="0,0,1 0,0,1 0,0,1 0,0,1 0,0,1 0,0,1 "
TextureCoordinates="0,0 1,0 1,1 1,1 0,1 0,0 "
Positions="-0.5,-0.5,0.5 0.5,-0.5,0.5 0.5,0.5,0.5 0.5,0.5,0.5 -0.5,0.5,0.5 -0.5,-0.5,0.5 " />
</GeometryModel3D.Geometry>
<!-- This material is applied to the front of the 3D object (red side).-->
<GeometryModel3D.Material>
<MaterialGroup>
<DiffuseMaterial>
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Red"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</MaterialGroup>
</GeometryModel3D.Material>
<!-- This material is applied to the back of the 3D object (blue side).-->
<GeometryModel3D.BackMaterial>
<MaterialGroup>
<DiffuseMaterial>
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Blue"/>
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</MaterialGroup>
</GeometryModel3D.BackMaterial>
<!-- The Transform specifies how to transform the 3D object. The properties of the
Rotation object are animated causing the 3D object to rotate (see Storyboard below).-->
<GeometryModel3D.Transform>
<RotateTransform3D>
<RotateTransform3D.Rotation>
<AxisAngleRotation3D x:Name="myAngleRotation" Axis="0,3,0" Angle="40" />
</RotateTransform3D.Rotation>
</RotateTransform3D>
</GeometryModel3D.Transform>
</GeometryModel3D>
</ModelVisual3D.Content>
</ModelVisual3D>
</Viewport3D.Children>
<!-- Trigger the rotation animation when the 3D object loads. This animation is used to show
both sides of the 3D object. -->
<Viewport3D.Triggers>
<EventTrigger RoutedEvent="Viewport3D.Loaded">
<BeginStoryboard>
<Storyboard>
<!-- This animation animates the Angle property of the AxisAngleRotation3D
making the 3D object rotate from -0 degrees to 360 degrees. -->
<DoubleAnimation
Storyboard.TargetName="myAngleRotation"
Storyboard.TargetProperty="Angle"
From="0" To="360" Duration="0:0:4" AutoReverse="True" RepeatBehavior="Forever"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Viewport3D.Triggers>
</Viewport3D>
</Canvas>
</Viewbox>
</DockPanel>
</Page>
