Do we have/need a glutPostRedisplay() and a glutIdleFunc() ?

open System
open System.Drawing
open System.Collections.Generic
 
open OpenTK
open OpenTK.Graphics
open OpenTK.Graphics.OpenGL
open OpenTK.Input
 
namespace Redbook.Double
 
type OTKWin() =
  inherit GameWindow(250, 250, GraphicsMode.Default, "Red Book Example 1-3")
 
  let mutable rectSpin = 0.f
  let rectSpinIncrement = 2.f
 
  do base.VSync <- VSyncMode.On
 
  member self.SpinRect =
    rectSpin <- rectSpin + rectSpinIncrement
    if rectSpin > 360.f then rectSpin <- rectSpin - 360.f
    // I want to glutPostRedisplay here, (I think!)
 
  override self.OnLoad e =
    base.OnLoad e
    GL.ClearColor(0.f, 0.f, 0.f, 0.f)
    GL.ShadeModel(ShadingModel.Flat)
 
  override self.OnRenderFrame(e) =
    base.OnRenderFrame e
    self.SpinRect  // This shouldn't be here, but I just wanted to see something happen :-)
    GL.Clear(ClearBufferMask.ColorBufferBit)
    GL.PushMatrix()
    GL.Rotate(rectSpin, 0.f, 0.f, 1.f)
    GL.Color3(1.f, 1.f, 1.f)
    GL.Rect(-25.f, -25.f, 25.f, 25.f)
    GL.PopMatrix()
    base.SwapBuffers()
 
  override self.OnResize e =
    base.OnResize e
    GL.Viewport(base.ClientRectangle.X, base.ClientRectangle.Y,
                base.ClientRectangle.Width, base.ClientRectangle.Height)
    GL.MatrixMode(MatrixMode.Projection)
    GL.LoadIdentity()
    GL.Ortho(-50., 50., -50., 50., -1., 1.)
    GL.MatrixMode(MatrixMode.Modelview)
    GL.LoadIdentity()
 
  override self.OnUpdateFrame e =
    base.OnUpdateFrame e
    if base.Keyboard.[Key.Escape] then base.Close()
 
[<EntryPoint>]
let main _ =
  let win = new OTKWin()
  do win.Run(30.)
  0