来自资源字典GetTemplateChild的WPF Viewport3d返回null

Question

I have added all my models as resource dictionaries as control template and i could load it using this code

 <Control Name="control" Width="507" Height="309" Template="{StaticResource SkeletonModel}"

now i want to edit that model in run time so iam trying to get the viewport3d that got loaded in the control element to edit it at runtime and i can't use triggers for it so i have to get reference to it then manipulate it from code behind here is the code i tried

  public partial class MainWindow : Window
    {
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            Viewport3D v = this.GetTemplateChild("ModelView") as Viewport3D;

        }

        public MainWindow()
        {
            InitializeComponent();
        }
    } 

v is always = null i also tried to change static resource to dynamic resource it didn't work i also tried couple of other ways like

Viewport3D v = control.Template.LoadContent() as Viewport3D;
            ModelVisual3D model;

            model = FindName("SkeletonHumanModel") as ModelVisual3D;

this does loads both the viewport and the model but when i edit either of them it does not get edited so i guess that loadcontent just loads a copy or another instance not the current instance used in the window here is the resource dictionary

<ResourceDictionary 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" 
                    mc:Ignorable="d"

    >
    <!--x:Class="Dynamic.ModelOperations"
                     x:ClassModifier="public"-->
    <ControlTemplate x:Key="SkeletonModel" >

        <Viewport3D Width="500" Height="500"  x:Name="ModelView"  ClipToBounds="True" >

            <Viewport3D.Camera>
                <PerspectiveCamera FieldOfView="35" FarPlaneDistance="110.57139405398024" LookDirection="0,0,-38.5951803220261" NearPlaneDistance="0.1" Position="-16.3927650451661,9.1631622056011,38.1892213715065" UpDirection="0,1,0"/>
            </Viewport3D.Camera>
            <ModelVisual3D x:Name="World">
                <ModelVisual3D x:Name="AmbientLightContainer">
                    <ModelVisual3D.Content>
                        <AmbientLight x:Name="AmbientLight" Color="#FF7F7F7F"/>
                    </ModelVisual3D.Content>
                </ModelVisual3D>
                <ModelVisual3D x:Name="DirectionalLightContainer">
                    <ModelVisual3D.Content>
                        <DirectionalLight x:Name="DirectionalLight" Color="#FF3F3F3F" Direction="0,0,-1">
                            <DirectionalLight.Transform>
                                <TranslateTransform3D OffsetZ="3" OffsetX="0" OffsetY="0"/>
                            </DirectionalLight.Transform>
                        </DirectionalLight>
                    </ModelVisual3D.Content>
                </ModelVisual3D>
                <ModelVisual3D x:Name="SkeletonHumanModel"   >.....

thanks in advance

Answer 1

To get a resource from ResourceDictionary, you should use FindResource() method. If your resource dictionary is merged in App resources, from MainWindow, you can get the resource like this,

private void OnLoaded(object sender, RoutedEventArgs e)
{
    var item = this.FindResource("SkeletonModel") as Viewport3D;
}