Code Snippet
using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Media3D;
namespace Shapes
{
//<SnippetSphere>
public class Sphere : UIElement3D
{
// <SnippetSummary>
// 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.
// </SnippetSummary>
//<SnippetOnUpdateModel>
protected override void OnUpdateModel()
{
GeometryModel3D model = new GeometryModel3D();
model.Geometry = Tessellate(ThetaDiv, PhiDiv, Radius);
model.Material = new DiffuseMaterial(Brushes.Blue);
Model = model;
}
//</SnippetOnUpdateModel>
//<SnippetModelProperty>
// 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);
}
}
//</SnippetModelProperty>
//<SnippetThetaProperty>
// 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);
}
}
//</SnippetThetaProperty>
//<SnippetPhiProperty>
// 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);
}
}
//</SnippetPhiProperty>
//<SnippetRadius>
// 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);
}
}
//</SnippetRadius>
//<SnippetPrivateMethods>
// 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 Point GetTextureCoordinate(double theta, double phi)
{
Point p = new Point(theta / (2 * Math.PI),
phi / (Math.PI));
return p;
}
//</SnippetPrivateMethods>
//<SnippetTessellate>
// 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;
}
//</SnippetTessellate>
}
//</SnippetSphere>
}
