Option Explicit

Dim x(4) As Long
Dim Y(4) As Long
Dim Z(4) As Long

Dim Xr(4) As Long
Dim Yr(4) As Long
Dim Zr(4) As Long
Dim Xd(4) As Long
Dim Yd(4) As Long

Dim Points As Long

Private Sub Form_Load()
  Points = 4
  x(0) = 100
  Y(0) = 100
  Z(0) = 1000

  x(1) = -100
  Y(1) = 100
  Z(1) = 1000

  x(2) = -100
  Y(2) = -100
  Z(2) = 2000

  x(3) = 100
  Y(3) = -100
  Z(3) = 2000
End Sub

Private Sub Command1_Click()
  Dim CenterX As Long, CenterY As Long
  Dim i As Integer, Rad As Double

  CenterX = Picture1.ScaleWidth / 2
  CenterY = Picture1.ScaleHeight / 2
  Command3.Enabled = True

  Rad = 6.28 / 100 * VScroll1.Value
  For i = 0 To Points - 1
    Xr(i) = Cos(Rad) * (x(i)) + Sin(Rad) * (Y(i))
    Yr(i) = Cos(Rad) * (Y(i)) - Sin(Rad) * (x(i))
    Zr(i) = Z(i)

    Xd(i) = Xr(i) * 512 / Zr(i) + CenterX
    Yd(i) = Yr(i) * 512 / Zr(i) + CenterY
  Next i

  Picture1.Cls

  For i = 0 To Points - 2
    Picture1.Line (Xd(i), Yd(i))-(Xd(i + 1), Yd(i + 1)), _
       RGB(255, 0, 0)
  Next i

  Picture1.Line (Xd(Points - 1), Yd(Points - 1))-(Xd(0), _
      Yd(0)), RGB(255, 0, 0)
End Sub

Private Sub Command3_Click()
  Dim x As Integer

  For x = VScroll1.Min To VScroll1.Max
    VScroll1.Value = x
  Next
End Sub

Private Sub VScroll1_Change()
  Command1_Click
End Sub

Private Sub VScroll1_Scroll()
  Command1_Click
End Sub