UIElement3D.OnUpdateModel Method

Definition

Namespace:

System.Windows

Assembly:

PresentationCore.dll

Participates in rendering operations when overridden in a derived class.

C#

protected virtual void OnUpdateModel();

Examples

The following example shows how to derive from the UIElement3D class to create a Sphere class:

C#

public class Sphere : UIElement3D
{
    // OnUpdateModel is called in response to InvalidateModel and provides
    // a place to set the Visual3DModel property.
    // 
    // Setting Visual3DModel does not provide parenting information, which
    // is needed for data binding, styling, and other features. Similarly, creating render data
    // in 2-D does not provide the connections either.
    // 
    // To get around this, we create a Model dependency property which
    // sets this value.  The Model DP then causes the correct connections to occur
    // and the above features to work correctly.
    // 
    // In this update model we retessellate the sphere based on the current
    // dependency property values, and then set it as the model.  The brush
    // color is blue by default, but the code can easily be updated to let
    // this be set by the user.

    protected override void OnUpdateModel()
    {
        GeometryModel3D model = new GeometryModel3D();

        model.Geometry = Tessellate(ThetaDiv, PhiDiv, Radius);
        model.Material = new DiffuseMaterial(System.Windows.Media.Brushes.Blue);

        Model = model;
    }

    // The Model property for the sphere
    private static readonly DependencyProperty ModelProperty =
        DependencyProperty.Register("Model",
                                    typeof(Model3D),
                                    typeof(Sphere),
                                    new PropertyMetadata(ModelPropertyChanged));

    private static void ModelPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Sphere s = (Sphere)d;
        s.Visual3DModel = s.Model;
    }

    private Model3D Model
    {
        get
        {
            return (Model3D)GetValue(ModelProperty);
        }

        set
        {
            SetValue(ModelProperty, value);
        }
    }

    // The number of divisions to make in the theta direction on the sphere
    public static readonly DependencyProperty ThetaDivProperty =
        DependencyProperty.Register("ThetaDiv",
                                    typeof(int),
                                    typeof(Sphere),
                                    new PropertyMetadata(15, ThetaDivPropertyChanged));

    private static void ThetaDivPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Sphere s = (Sphere)d;
        s.InvalidateModel();
    }

    public int ThetaDiv
    {
        get
        {
            return (int)GetValue(ThetaDivProperty);
        }

        set
        {
            SetValue(ThetaDivProperty, value);
        }
    }

    // The number of divisions to make in the phi direction on the sphere
    public static readonly DependencyProperty PhiDivProperty =
        DependencyProperty.Register("PhiDiv",
                                    typeof(int),
                                    typeof(Sphere),
                                    new PropertyMetadata(15, PhiDivPropertyChanged));

    private static void PhiDivPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Sphere s = (Sphere)d;
        s.InvalidateModel();
    }

    public int PhiDiv
    {
        get
        {
            return (int)GetValue(PhiDivProperty);
        }

        set
        {
            SetValue(PhiDivProperty, value);
        }
    }

    // The radius of the sphere
    public static readonly DependencyProperty RadiusProperty =
        DependencyProperty.Register("Radius",
                                    typeof(double),
                                    typeof(Sphere),
                                    new PropertyMetadata(1.0, RadiusPropertyChanged));

    private static void RadiusPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Sphere s = (Sphere)d;
        s.InvalidateModel();
    }

    public double Radius
    {
        get
        {
            return (double)GetValue(RadiusProperty);
        }

        set
        {
            SetValue(RadiusProperty, value);
        }
    }

    // Private helper methods
    private static Point3D GetPosition(double theta, double phi, double radius)
    {
        double x = radius * Math.Sin(theta) * Math.Sin(phi);
        double y = radius * Math.Cos(phi);
        double z = radius * Math.Cos(theta) * Math.Sin(phi);

        return new Point3D(x, y, z);
    }

    private static Vector3D GetNormal(double theta, double phi)
    {
        return (Vector3D)GetPosition(theta, phi, 1.0);
    }

    private static double DegToRad(double degrees)
    {
        return (degrees / 180.0) * Math.PI;
    }

    private static System.Windows.Point GetTextureCoordinate(double theta, double phi)
    {
        System.Windows.Point p = new System.Windows.Point(theta / (2 * Math.PI),
                            phi / (Math.PI));

        return p;
    }

    // Tesselates the sphere and returns a MeshGeometry3D representing the 
    // tessellation based on the given parameters
    internal static MeshGeometry3D Tessellate(int tDiv, int pDiv, double radius)
    {            
        double dt = DegToRad(360.0) / tDiv;
        double dp = DegToRad(180.0) / pDiv;

        MeshGeometry3D mesh = new MeshGeometry3D();

        for (int pi = 0; pi <= pDiv; pi++)
        {
            double phi = pi * dp;

            for (int ti = 0; ti <= tDiv; ti++)
            {
                // we want to start the mesh on the x axis
                double theta = ti * dt;

                mesh.Positions.Add(GetPosition(theta, phi, radius));
                mesh.Normals.Add(GetNormal(theta, phi));
                mesh.TextureCoordinates.Add(GetTextureCoordinate(theta, phi));
            }
        }

        for (int pi = 0; pi < pDiv; pi++)
        {
            for (int ti = 0; ti < tDiv; ti++)
            {
                int x0 = ti;
                int x1 = (ti + 1);
                int y0 = pi * (tDiv + 1);
                int y1 = (pi + 1) * (tDiv + 1);

                mesh.TriangleIndices.Add(x0 + y0);
                mesh.TriangleIndices.Add(x0 + y1);
                mesh.TriangleIndices.Add(x1 + y0);

                mesh.TriangleIndices.Add(x1 + y0);
                mesh.TriangleIndices.Add(x0 + y1);
                mesh.TriangleIndices.Add(x1 + y1);
            }
        }

        mesh.Freeze();
        return mesh;
    }
}

Remarks

When you derive a class from the UIElement3D class, you can use this method together with the InvalidateModel method to refresh the model of the element.

You only need to call this method in advanced scenarios. One such advanced scenario is if the derived class has multiple properties that affect the appearance, and you want to update the underlying model only once. Within the OnUpdateModel method you could update the Visual3DModel property of the Visual3D class.

This method has no default implementation in the UIElement3D class.

Applies to