Microsoft Small Basic

Program Listing:

GraphicsWindow.BackgroundColor = "Wheat"
eyeball_num = 5
For i = 1 to eyeball_num
rad[i] = Math.GetRandomNumber(150)+50
pupilrad[i] = rad[i]/5
irisrad[i] = pupilrad[i]*1.5
eyecolor[i] = GraphicsWindow.GetRandomColor()
GraphicsWindow.BrushColor = "White"
eyeball[i] = Shapes.AddEllipse(rad[i],rad[i])
GraphicsWindow.BrushColor = eyecolor[i]
iris[i] = Shapes.AddEllipse(irisrad[i],irisrad[i])
GraphicsWindow.BrushColor = "Black"
pupil[i] = Shapes.AddEllipse(pupilrad[i],pupilrad[i])
posX[i] = Math.GetRandomNumber(GraphicsWindow.Width-rad[i])
posY[i] = Math.GetRandomNumber(GraphicsWindow.Height-rad[i])
Shapes.Move(pupil[i],posX[i]-pupilrad[i]/2,posY[i]-pupilrad[i]/2)
Shapes.Move(eyeball[i],posX[i]-rad[i]/2,posY[i]-rad[i]/2)
Shapes.Move(iris[i],posX[i]-irisrad[i]/2,posY[i]-irisrad[i]/2)
EndFor
GraphicsWindow.MouseDown = MouseDown
GraphicsWindow.MouseUp = MouseUp
While ("True")
  For g = 1 To eyeball_num
  getAngle()
  distfromcenter[g] = Math.SquareRoot(Math.Abs(dx[g]*dx[g]+dy[g]*dy[g]))
  yOnEyeball[g] = Math.Sin(angle[g])*Math.Min(rad[g]/2-irisrad[g]/2,distfromcenter[g]/3)
  xOnEyeball[g] = Math.Cos(angle[g])*Math.Min(rad[g]/2-irisrad[g]/2,distfromcenter[g]/3)
  Shapes.Move(pupil[g],posX[g]+xOnEyeball[g]-pupilrad[g]/2,posY[g]+yOnEyeball[g]-pupilrad[g]/2)
  Shapes.Move(iris[g],posX[g]+xOnEyeball[g]-irisrad[g]/2,posY[g]+yOnEyeball[g]-irisrad[g]/2)
  EndFor
  Program.Delay(10)
EndWhile

Sub getAngle
  dx[g] = GraphicsWindow.MouseX - posX[g]
  dy[g] = GraphicsWindow.MouseY - posY[g]
  If (dx[g] = 0) Then
    angle[g] = Math.Pi/2
    If (dy[g] < 0) Then
      angle[g] = -angle[g]
    EndIf
  Else
    angle[g] = Math.ArcTan(dy[g]/dx[g])
  EndIf
  If (dx[g] < 0) Then
    angle[g] = angle[g]+Math.Pi
  EndIf
EndSub
Sub MouseDown
  For r = 1 To eyeball_num
    Shapes.Zoom(iris[r],1.2,1.2)
    Shapes.Zoom(pupil[r],1.2,1.2)
  EndFor
EndSub
Sub MouseUp
  For w = 1 To eyeball_num
    Shapes.Zoom(iris[w],1,1)
    Shapes.Zoom(pupil[w],1,1)
  EndFor
EndSub