F# WPF - 在 Viewport3D 中显示简单对象

Question

我试图用很少的时间和很少的 F# 初步知识来在 F# 中生成 3D 图形（从我之前的问题可以明显看出）。我正在研究托马斯·佩特里克（Tomas Petricek）的分形示例，但我无法真正理解它。我成功地在 XAML 中定义了一个带有 Viewport3D 对象的窗口，从 F# 初始化并显示它。但就在 F# 中创建 3D 对象并显示它们而言，我迷失在分形生成、坐标转换和其他计算的海洋中。 有人可以提供一个简单的示例，在 F# 中创建一个非常简单的对象（单个立方体，或只是一个三角形）并将其显示在 WPF 窗口中吗？这将是巨大的帮助。 谢谢。

Answer 1

这是一个简单的例子，用两个三角形组成一个正方形：

#if INTERACTIVE
    #r "PresentationCore"
    #r "PresentationFramework"
    #r "WindowsBase"
    #r "System.Xaml"
#endif


open System.Windows
open System.Windows.Controls
open System.Windows.Media
open System.Windows.Media.Media3D

let grp = Model3DGroup()
let geo = MeshGeometry3D()

// Point collection
for x,y,z in [0.5, 0.0, 0.0; 
              1.0, 0.0, 0.0;
              0.5, 0.5, 0.0;
              1.0, 0.5, 0.0] do
    geo.Positions.Add(Point3D(x,y,z))

// First triangle
for i in [0;1;2] do geo.TriangleIndices.Add(i)

// Second triangle - order matters for deciding front vs. back
for i in [2;1;3] do geo.TriangleIndices.Add(i)

// Create a model with the mesh and a front and back material
let model = 
    GeometryModel3D(
        Geometry = geo, 
        Material = DiffuseMaterial(Brushes.Black), 
        BackMaterial = DiffuseMaterial(Brushes.Red))

grp.Children.Add(model)

// add light so back color is visible
grp.Children.Add(AmbientLight())

// set up a continuous rotation around the y-axis
let rotation = AxisAngleRotation3D(Axis = Vector3D(0.,1.,0.))
let anim = 
    Animation.DoubleAnimation(0.0, 360., Duration(System.TimeSpan.FromSeconds 2.), 
        RepeatBehavior = Animation.RepeatBehavior.Forever)
rotation.BeginAnimation(AxisAngleRotation3D.AngleProperty, anim)

// apply the rotation to the geometry
grp.Transform <- RotateTransform3D(rotation)

// create a camera pointing at the triangle
let cam = PerspectiveCamera(Point3D(0.,0.,2.), Vector3D(0., 0., -1.), Vector3D(0., 1., 0.), 60.)

// set the viewport up with the camera and geometry
let vprt = Viewport3D(Camera = cam)
vprt.Children.Add(ModelVisual3D(Content = grp))

// add the viewport to a window
let wnd = Window(Content = vprt, Title = "3D", Visibility = Visibility.Visible)