Question

In flash10 I can easly rotate an image around its center in 3D space.

The flash10 example I have is at [http://jsc.sourceforge.net/examples/web/MatrixStuffExample/Application.htm

_{(source: sourceforge.net)}

I want to port this example to WPF.

Is there an example how to do such 3D transformation in WPF within C# without XAML?

In silverlight 3 you’d be using Matrix3DProjection. How would you implement in WPF?

Answer 1

I’ve set up a basic thin cube and rotated it round so you can see how the transform works through C#.

Setup your Viewport in the xaml

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <StackPanel>

        <Viewport3D Name="mainViewport" ClipToBounds="True" HorizontalAlignment="Stretch" Height="300">
            <Viewport3D.Camera>
                <PerspectiveCamera 
                      LookDirection="0,0,-20"
                      UpDirection="0,1,0"
                      Position="0,0,50" 
                      />
            </Viewport3D.Camera>
            <ModelVisual3D>
                <ModelVisual3D.Content>
                    <Model3DGroup x:Name="group3d">

                        <SpotLight Position="10,10,10" x:Name="mySpotLight" Color="Yellow"  InnerConeAngle="15" OuterConeAngle="100" Range="100" />
                    </Model3DGroup>
                </ModelVisual3D.Content>

            </ModelVisual3D>
        </Viewport3D>

    </StackPanel>
</Window>

And heres the code behind, the transformation is the last method … hope this helps … give me a shout if you want more info!

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();
        Init();
    }


    private Timer _timer;
    private ModelVisual3D _model = new ModelVisual3D();
    private double _angle = 0;

    public void Init()
    {
        _model = GetCube(GetSurfaceMaterial(Colors.Red), new Point3D(10, 10, 1), new Point3D(-10,-10,-1));
        mainViewport.Children.Add(_model);    
        _timer = new Timer(10);
        _timer.Elapsed += TimerElapsed;
        _timer.Enabled = true;
    }

    void TimerElapsed(object sender, ElapsedEventArgs e)
    {
        Dispatcher.Invoke(DispatcherPriority.Normal, new Action<double>(Transform), 0.5d);
    }

    public MaterialGroup GetSurfaceMaterial(Color colour)
    {
        var materialGroup = new MaterialGroup();
        var emmMat = new EmissiveMaterial(new SolidColorBrush(colour));
        materialGroup.Children.Add(emmMat);
        materialGroup.Children.Add(new DiffuseMaterial(new SolidColorBrush(colour)));
        var specMat = new SpecularMaterial(new SolidColorBrush(Colors.White), 30);
        materialGroup.Children.Add(specMat);
        return materialGroup;
    }

    public ModelVisual3D GetCube(MaterialGroup materialGroup, Point3D nearPoint, Point3D farPoint)
    {
        var cube = new Model3DGroup();
        var p0 = new Point3D(farPoint.X, farPoint.Y, farPoint.Z);
        var p1 = new Point3D(nearPoint.X, farPoint.Y, farPoint.Z);
        var p2 = new Point3D(nearPoint.X, farPoint.Y, nearPoint.Z);
        var p3 = new Point3D(farPoint.X, farPoint.Y, nearPoint.Z);
        var p4 = new Point3D(farPoint.X, nearPoint.Y, farPoint.Z);
        var p5 = new Point3D(nearPoint.X, nearPoint.Y, farPoint.Z);
        var p6 = new Point3D(nearPoint.X, nearPoint.Y, nearPoint.Z);
        var p7 = new Point3D(farPoint.X, nearPoint.Y, nearPoint.Z);
        //front side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p3, p2, p6));
        cube.Children.Add(CreateTriangleModel(materialGroup, p3, p6, p7));
        //right side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p2, p1, p5));
        cube.Children.Add(CreateTriangleModel(materialGroup, p2, p5, p6));
        //back side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p1, p0, p4));
        cube.Children.Add(CreateTriangleModel(materialGroup, p1, p4, p5));
        //left side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p0, p3, p7));
        cube.Children.Add(CreateTriangleModel(materialGroup, p0, p7, p4));
        //top side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p7, p6, p5));
        cube.Children.Add(CreateTriangleModel(materialGroup, p7, p5, p4));
        //bottom side triangles
        cube.Children.Add(CreateTriangleModel(materialGroup, p2, p3, p0));
        cube.Children.Add(CreateTriangleModel(materialGroup, p2, p0, p1));
        var model = new ModelVisual3D();
        model.Content = cube;
        return model;
    }

    private Model3DGroup CreateTriangleModel(Material material, Point3D p0, Point3D p1, Point3D p2)
    {
        var mesh = new MeshGeometry3D();
        mesh.Positions.Add(p0);
        mesh.Positions.Add(p1);
        mesh.Positions.Add(p2);
        mesh.TriangleIndices.Add(0);
        mesh.TriangleIndices.Add(1);
        mesh.TriangleIndices.Add(2);
        var normal = CalculateNormal(p0, p1, p2);
        mesh.Normals.Add(normal);
        mesh.Normals.Add(normal);
        mesh.Normals.Add(normal);

        var model = new GeometryModel3D(mesh, material);

        var group = new Model3DGroup();
        group.Children.Add(model);
        return group;
    }

    private Vector3D CalculateNormal(Point3D p0, Point3D p1, Point3D p2)
    {
        var v0 = new Vector3D(p1.X - p0.X, p1.Y - p0.Y, p1.Z - p0.Z);
        var v1 = new Vector3D(p2.X - p1.X, p2.Y - p1.Y, p2.Z - p1.Z);
        return Vector3D.CrossProduct(v0, v1);
    }

    void Transform(double adjustBy)
    {
        _angle += adjustBy;


        var rotateTransform3D = new RotateTransform3D {CenterX = 0, CenterZ = 0};
        var axisAngleRotation3D = new AxisAngleRotation3D {Axis = new Vector3D(0, 1, 0), Angle = _angle};
        rotateTransform3D.Rotation = axisAngleRotation3D;
        var myTransform3DGroup = new Transform3DGroup();
        myTransform3DGroup.Children.Add(rotateTransform3D);
        _model.Transform = myTransform3DGroup;

    }


}