Bits & Bytes

In this post, I explain the basic Windows Presentation Foundation programming elements of a 3D scene in C#. The C# code that I use for demonstration creates a simple tetrahedron model and rotates it around the vertical axis.

To create the project, follow these steps:

1. Begin with the project from our prior blog post, or create a new WPF project.
   
2. Add a class file to the project: left-click PROJECT in the menubar and left-click Add Class… in the submenu.
   
3. This pops up the Add New Item dialog. Select Installed->Visual C# Items in the left-hand pane.
   
4. Then left-click Class in the center pane to select it.
   
5. Finally, rename the class by left-clicking the text box next to Name: at the bottom of the window and entering CScene3d.cs. Finish adding the class by left-clicking the Add button.
6. Next, copy the code for “CScene3D.cs” below into the file of the same name in your project.
7. Finally, finish the code by adding this line to “Program.cs” as shown in the code below to allow the window to display the 3D scene:

   qWindow.Content = TestScenes.Test5();

8. Compile and execute the program by left-clicking DEBUG in the menubar and left-clicking Start Without Debugging in the submenu. After a few seconds, the code will be compiled and a window will pop up displaying a rotating tetrahedron.

The WPF scene creation in “CScene3D.cs” consists of a few basic steps, which can be outlined as follows:

1. Create a camera and add it.
2. Create a lighting model and add it.
3. Create a geometric model and add it
   1. Create points, triangles, and normals
   2. Set the material properties
   3. Create and apply transforms

For simplicity, I have skipped some steps, like adding normals, and accepted default values for much of the rest. At the end, I have collected components to added them appropriately. Pay close attention to that.

Program.cs

using System;
using System.Windows;

namespace ConsoleApplication {
    class Program {
        [STAThread]
        static void Main(string[] args) {
            Window qWindow = new Window();
            qWindow.Title = "WPF in Console";
            qWindow.Width = 400;
            qWindow.Height = 300;
            qWindow.Content = CScene3D.Test();
            qWindow.ShowDialog();
        }
    }
}

CScene3D.cs

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Media3D;
using System.Windows.Media.Animation;

namespace ConsoleApplication {
    class CScene3D {
        // Animation - Tetrahedron (upright, looking slightly up from below)
        public static Viewport3D Test() {

            // Define the camera
            PerspectiveCamera myPCamera = new PerspectiveCamera();
            myPCamera.Position = new Point3D(0, .2, 3);

            // Define a lighting model
            DirectionalLight myDirectionalLight = new DirectionalLight();

            // Define the geometry
            const double kdSqrt2 = 1.4142135623730950488016887242097;
            const double kdSqrt6 = 2.4494897427831780981972840747059;
            // Create a collection of vertex positions
            Point3DCollection myPositionCollection = new Point3DCollection();
            myPositionCollection.Add(new Point3D(0.0, 1.0, 0.0));
            myPositionCollection.Add(new Point3D(2.0 * kdSqrt2 / 3.0, -1.0 / 3.0, 0.0));
            myPositionCollection.Add(new Point3D(-kdSqrt2 / 3.0, -1.0 / 3.0, kdSqrt6 / 3.0));
            myPositionCollection.Add(new Point3D(-kdSqrt2 / 3.0, -1.0 / 3.0, -kdSqrt6 / 3.0));
            // Create a collection of triangle indices
            Int32Collection myTriangleIndicesCollection = new Int32Collection();
            // Triangle
            myTriangleIndicesCollection.Add(0);
            myTriangleIndicesCollection.Add(2);
            myTriangleIndicesCollection.Add(1);
            // Triangle
            myTriangleIndicesCollection.Add(0);
            myTriangleIndicesCollection.Add(1);
            myTriangleIndicesCollection.Add(3);
            // Triangle
            myTriangleIndicesCollection.Add(0);
            myTriangleIndicesCollection.Add(3);
            myTriangleIndicesCollection.Add(2);
            // Triangle
            myTriangleIndicesCollection.Add(1);
            myTriangleIndicesCollection.Add(2);
            myTriangleIndicesCollection.Add(3);
            MeshGeometry3D myMeshGeometry3D = new MeshGeometry3D();
            myMeshGeometry3D.Positions = myPositionCollection;
            myMeshGeometry3D.TriangleIndices = myTriangleIndicesCollection;
            // Apply the mesh to the geometry model.
            GeometryModel3D myGeometryModel = new GeometryModel3D();
            myGeometryModel.Geometry = myMeshGeometry3D;

            // Define the material for the geometry
            SolidColorBrush qColorBrush = new SolidColorBrush(Color.FromArgb(255, 0, 255, 0));
            DiffuseMaterial myMaterial = new DiffuseMaterial(qColorBrush);
            myGeometryModel.Material = myMaterial;

            // Define the transformation, if any. In this case, we use an animated transformation
            RotateTransform3D myRotateTransform = 
                new RotateTransform3D(new AxisAngleRotation3D(new Vector3D(0, 1, 0), 1));
            DoubleAnimation myAnimation = new DoubleAnimation();
            myAnimation.From = 1;
            myAnimation.To = 361;
            myAnimation.Duration = new Duration(TimeSpan.FromMilliseconds(5000));
            myAnimation.RepeatBehavior = RepeatBehavior.Forever;
            myRotateTransform.Rotation.BeginAnimation(AxisAngleRotation3D.AngleProperty, myAnimation);
            myGeometryModel.Transform = myRotateTransform;

            // Collect the components
            Model3DGroup myModel3DGroup = new Model3DGroup();
            myModel3DGroup.Children.Add(myDirectionalLight);
            myModel3DGroup.Children.Add(myGeometryModel);
            ModelVisual3D myModelVisual3D = new ModelVisual3D();
            myModelVisual3D.Content = myModel3DGroup;
            Viewport3D myViewport3D = new Viewport3D();
            myViewport3D.Children.Add(myModelVisual3D);
            myViewport3D.Camera = myPCamera;

            return myViewport3D;
        }
    }
}