Como: Animar uma rotação 3D usando quadros-chave

  • Artigo

No exemplo a seguir, Rotation3DAnimationUsingKeyFrames é usado para fazer um objeto 3D girar enquanto seu eixo de rotação anima resultando em uma "oscilação". Essa animação usa os seguintes quadros-chave:

  1. LinearRotation3DKeyFrame é usado para criar uma interpolação suave e linear entre valores.

  2. DiscreteRotation3DKeyFrame é usado para criar "saltos" repentinos entre valores (sem interpolação).

  3. SplineRotation3DKeyFrame é usado para criar uma transição de variável entre valores dependendo da KeySpline propriedade. No exemplo abaixo, essa parte da animação começa lenta, mas no final do segmento de tempo, acelera exponencialmente.

Exemplo

<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 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>

                  <!-- 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 properties of the
                        Rotation object are animated causing the 3D object to rotate and "wobble" (see Storyboard below).-->
                  <GeometryModel3D.Transform>
                    <RotateTransform3D x:Name="myRotateTransform3D" >
                      <RotateTransform3D.Rotation>
                        <AxisAngleRotation3D 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. -->
          <Viewport3D.Triggers>
            <EventTrigger RoutedEvent="Viewport3D.Loaded">
              <BeginStoryboard>
                <Storyboard>

                  <!-- This animation animates the Rotation property of the RotateTransform
                       causing the 3D shape to rotate and wobble as the rotation angle and 
                       axis are animated. -->
                  <Rotation3DAnimationUsingKeyFrames
                   Storyboard.TargetName="myRotateTransform3D" 
                   Storyboard.TargetProperty="Rotation" >
                    <Rotation3DAnimationUsingKeyFrames.KeyFrames>

                      <!-- Using a LinearRotation3DKeyFrame, the object gradually rotates to an angle 
                           of -60 degrees while the axis of rotation shifts (animates) to a new value. -->
                      <LinearRotation3DKeyFrame KeyTime="0:0:1">
                        <LinearRotation3DKeyFrame.Value>
                          <AxisAngleRotation3D Axis="1,0,1" Angle="-60" />
                        </LinearRotation3DKeyFrame.Value>
                      </LinearRotation3DKeyFrame>

                      <!-- Using a DiscreteRotation3DKeyFrame, the object suddenly rotates to the an angle 
                           of 80 degrees on a new axis. This happens immdeiately after the first 1 and 
                           a half seconds of the animation. -->
                      <DiscreteRotation3DKeyFrame KeyTime="0:0:1.5">
                        <DiscreteRotation3DKeyFrame.Value>
                          <AxisAngleRotation3D Axis="0,0,1" Angle="80" />
                        </DiscreteRotation3DKeyFrame.Value>
                      </DiscreteRotation3DKeyFrame>

                      <!-- Using a SplineRotation3DKeyFrame, the object rotates back to its starting position. 
                           The animation starts out slowly at first and then speeds up. This KeyFrame ends 
                           after the fourth second. -->
                      <SplineRotation3DKeyFrame KeySpline="0.6,0.0 0.9,0.00" KeyTime="0:0:4">
                        <SplineRotation3DKeyFrame.Value>
                          <AxisAngleRotation3D Axis="0,3,0" Angle="40" />
                        </SplineRotation3DKeyFrame.Value>
                      </SplineRotation3DKeyFrame>

                    </Rotation3DAnimationUsingKeyFrames.KeyFrames>
                  </Rotation3DAnimationUsingKeyFrames>

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

    </Viewbox>
  </DockPanel>
</Page>

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