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QuaternionAnimation.By Property

Gets or sets the total amount by which the animation changes its starting value.

Namespace:  System.Windows.Media.Animation
Assembly:  PresentationCore (in PresentationCore.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

public Nullable<Quaternion> By { get; set; }
<object>  <object.By>    <Quaternion />  </object.By></object>
<object By="Quaternion"/>- or -<object By="{x:Null Markup Extension}"/>

Property Value

Type: System.Nullable<Quaternion>
The total amount by which the animation changes its starting value. The default value is null.

Identifier field

ByProperty

Metadata properties set to true

None

Use the By property when you want to animate a value "by" a certain amount, rather than specifying a starting or ending value. You may also use the By property with the From property. The following table summarizes how the From, To, and By properties may be used together or separately to determine an animation's target values.

Properties specified

Resulting behavior

From

The animation progresses from the value specified by the From property to the base value of the property being animated or to a previous animation's output value, depending on how the previous animation is configured.

From and To

The animation progresses from the value specified by the From property to the value specified by the To property.

From and By

The animation progresses from the value specified by the From property to the value specified by the sum of the From and By properties.

To

The animation progresses from the animated property's base value or a previous animation's output value to the value specified by the To property.

By

The animation progresses from the base value of the property being animated or a previous animation's output value to the sum of that value and the value specified by the By property.

Note   If you set both the To and By properties, the To property takes precedence and the By property is ignored.

To use other interpolation methods or animate between more than two target values, use a QuaternionAnimationUsingKeyFrames object.

This example shows how to animate a rotation of a 3-D object using quaternions.

The code below shows a QuaternionRotation3D used as the value for the Rotation property of a RotateTransform3D.

<!-- The Transform specifies how to transform the 3D object. The rotation
     is animated using the Storyboard below. -->
<GeometryModel3D.Transform>
  <RotateTransform3D>
    <RotateTransform3D.Rotation>
      <QuaternionRotation3D x:Name="myQuaternionRotation3D" />
    </RotateTransform3D.Rotation>
  </RotateTransform3D>
</GeometryModel3D.Transform>

This QuaternionRotation3D is animated with a QuaternionAnimation within a Storyboard using the code below.

<!-- Trigger the rotation animation when the 3D object loads. -->
<Viewport3D.Triggers>
  <EventTrigger RoutedEvent="Viewport3D.Loaded">
    <BeginStoryboard>
      <Storyboard>

        <!-- This animation animates the Rotation property of the RotateTransform3D
             causing the 3D shape to rotate. -->
        <QuaternionAnimation
         Storyboard.TargetName="myQuaternionRotation3D"
         Storyboard.TargetProperty="Quaternion" From="0,0,1,0" To="0.3, 0.3, 1, 0" 
         Duration="0:0:2" />

      </Storyboard>
    </BeginStoryboard>
  </EventTrigger>
</Viewport3D.Triggers>

The following code shows the entire sample.

<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>

            <!-- This ModelVisual3D defines 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>
                <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>

                  <!-- The material specifies the material applied to the plane. In this case it is a linear gradient.-->
                  <GeometryModel3D.Material>
                    <MaterialGroup>
                      <DiffuseMaterial>
                        <DiffuseMaterial.Brush>
                          <LinearGradientBrush StartPoint="0,0.5" EndPoint="1,0.5">
                            <LinearGradientBrush.GradientStops>
                              <GradientStop Color="Yellow" Offset="0" />
                              <GradientStop Color="Red" Offset="0.25" />
                              <GradientStop Color="Blue" Offset="0.75" />
                              <GradientStop Color="LimeGreen" Offset="1" />
                            </LinearGradientBrush.GradientStops>
                          </LinearGradientBrush>
                        </DiffuseMaterial.Brush>
                      </DiffuseMaterial>
                    </MaterialGroup>
                  </GeometryModel3D.Material>
                  <!-- The Transform specifies how to transform the 3D object. The rotation
                       is animated using the Storyboard below. -->
                  <GeometryModel3D.Transform>
                    <RotateTransform3D>
                      <RotateTransform3D.Rotation>
                        <QuaternionRotation3D x:Name="myQuaternionRotation3D" />
                      </RotateTransform3D.Rotation>
                    </RotateTransform3D>
                  </GeometryModel3D.Transform>
                </GeometryModel3D>
              </ModelVisual3D.Content>
            </ModelVisual3D>
          </Viewport3D.Children>
          <!-- Trigger the rotation animation when the 3D object loads. -->
          <Viewport3D.Triggers>
            <EventTrigger RoutedEvent="Viewport3D.Loaded">
              <BeginStoryboard>
                <Storyboard>

                  <!-- This animation animates the Rotation property of the RotateTransform3D
                       causing the 3D shape to rotate. -->
                  <QuaternionAnimation
                   Storyboard.TargetName="myQuaternionRotation3D"
                   Storyboard.TargetProperty="Quaternion" From="0,0,1,0" To="0.3, 0.3, 1, 0" 
                   Duration="0:0:2" />

                </Storyboard>
              </BeginStoryboard>
            </EventTrigger>
          </Viewport3D.Triggers>
        </Viewport3D>
      </Canvas>
    </Viewbox>
  </DockPanel>
</Page>

More Code

How to: Control an Animation using From, To, and ByA "From/To/By" or "basic animation" creates a transition between two target values (see Animation Overview for an introduction to different types of animations). To set the target values of a basic animation, use its From, To, and By properties. The following table summarizes how the From, To, and By properties may be used together or separately to determine an animation's target values.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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