如何动态修改AxisAngleRotation里的角度值？

Question

我想做一个能从串口里面读取传感器传入的现实单摆的角度，然后能在WPF上模拟的3D动画，目前已经做出了3D模型和简单动画，但是没法动态修改AxisAngleRotation3D里的Angle值，它只能简单地从From到To……求高人帮忙改改。程序如下~假定我在C#里，传入的角度值是nowangle，目的就是想，让AxisAngleRotation3D的Angle值一直和nowangle保持一致，该怎么写呢？C#代码：public partial class MainWindow : Window
{
        public double nowangle;
        public Storyboard sb1 = new Storyboard();
        public DoubleAnimation da1 = new DoubleAnimation();
  public MainWindow()
  {
   this.InitializeComponent();
            getanimation();
            sb1.Begin();
            
        }
        private void getanimation() {
            #region
            da1.SetValue(Storyboard.TargetNameProperty, "rotation");
            da1.SetValue(Storyboard.TargetPropertyProperty, new      PropertyPath(AxisAngleRotation3D.AngleProperty));
            da1.From = rotation.Angle;
            da1.To += nowangle;
            //da1.Duration = TimeSpan.FromSeconds(0.5);
            //da1.AutoReverse = true;
            //da1.RepeatBehavior = RepeatBehavior.Forever;
            sb1.Children.Add(da1);
            this.Resources.Add("Storyboard", sb1);
            #endregion
        }
}
XAML：   <Grid>
  <Viewport3D ClipToBounds="False" Margin="56,0,62,13">
   <Viewport3D.Camera>
    <PerspectiveCamera FieldOfView="60"  LookDirection="0,0,-230"  Position="0,-80,230" UpDirection="0,1,0"/>
   </Viewport3D.Camera>
            
   <ModelVisual3D x:Name="World">
                
    <ModelVisual3D.Transform>
                    <RotateTransform3D>
                        <RotateTransform3D.Rotation>
                            <AxisAngleRotation3D 
                                x:Name="rotation"
                                Axis="0,0,1"
                                Angle="0"
                                />
                        </RotateTransform3D.Rotation>
                    </RotateTransform3D>
                </ModelVisual3D.Transform>
                
    <ModelVisual3D x:Name="DirectionalLightContainer">
     <ModelVisual3D.Content>
      <DirectionalLight x:Name="DirectionalLight" Color="White" Direction="-120,-150,-230">
      </DirectionalLight>
     </ModelVisual3D.Content>
    </ModelVisual3D>
                
    <ModelVisual3D x:Name="RootGeometryContainer">
                    
     <ModelVisual3D x:Name="Sphere01">
      <ModelVisual3D.Content>
       <GeometryModel3D x:Name="DefaultMaterial" d:Bounds="-10,-110,-10,20,20,20">
        <GeometryModel3D.Geometry>
         <MeshGeometry3D Normals="..." TriangleIndices="..."/>
        </GeometryModel3D.Geometry>
        <GeometryModel3D.Material>
         <DiffuseMaterial Brush="Red"/>
        </GeometryModel3D.Material>
       </GeometryModel3D>
      </ModelVisual3D.Content>
     </ModelVisual3D>
                    
     <ModelVisual3D x:Name="Cylinder01">
      <ModelVisual3D.Content>
       <GeometryModel3D x:Name="DefaultMaterial1" d:Bounds="-0.5,-100,-0.49210000038147,1,100,0.984800010919571">
        <GeometryModel3D.Geometry>
         <MeshGeometry3D Normals="..." TriangleIndices="..."/>
        </GeometryModel3D.Geometry>
        <GeometryModel3D.Material>
         <DiffuseMaterial Brush="Brown"/>
        </GeometryModel3D.Material>
       </GeometryModel3D>
      </ModelVisual3D.Content>
     </ModelVisual3D>
                    
    </ModelVisual3D>
   </ModelVisual3D>
            
  </Viewport3D>
</Grid>