Programming WPF, 2nd Edition

Models

We describe three-dimensional objects in WPF by building a tree of Model3D objects. Model3D is an abstract class, and we use the derived GeometryModel3D type to define a particular 3D shape. Another derived type, Model3DGroup, allows us to combine several Model3D objects into one composite Model3D. There are also various light source types derived from Model3D, which we describe later in the "Lights" section.

Example 17-2 shows the basic structure of a very simple model.

Example 17-2. A simple 3D model

<Model3DGroup>

  <DirectionalLight Direction="0,0,-1" />

  <GeometryModel3D>
    ...
  </GeometryModel3D>

</Model3DGroup>

This uses a Model3DGroup to build a model containing a light source (a DirectionalLight, in this case) and a GeometryModel3D. The example is not complete, as we need to provide the GeometryModel3D with two pieces of information. It needs to know what the surface of the shape should look like—what color it should be, and whether its finish should be matte or reflective. It also needs a description of the shape, which a Geometry3D provides.

Geometry3D

As you saw in Chapter 13, WPF defines 2D shapes with the various types derived from Geometry. It should therefore come as no surprise that 3D shapes are defined by classes derived from Geometry3D. However, whereas the 2D world offers various different kinds of geometries, such as EllipseGeometry, RectangleGeometry, and PathGeometry, WPF currently offers only one concrete Geometry3D: MeshGeometry3D.

A MeshGeometry3D defines the ...