Visual Basic - Paint, lineas curvas

Estoy haciendo un paint en Visual Basic, y soi incapaz de hacer líneas curvas, el código que intento utilizar es el siguiente:

Option Explicit
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
Static C1 As Boolean
Static C2 As Boolean
Static X1, X2, X3, Y1, Y2, Y3 As Integer
Dim A, B, C, d As Integer
If C1 = False Then
C1 = True
X1 = X
Y1 = Y
Label1.Caption = "Seleccione el punto final."
ElseIf C1 = True And C2 = False Then
C2 = True
X2 = X
Y2 = Y
Label1.Caption = "Seleccione el punto de curvatura."
ElseIf C1 = True And C2 = True Then
C2 = False
C1 = False
X3 = X
Y3 = Y
A = X3 - X1
B = Y3 - Y1
Do
C = C + 10
Line (X1, Y1)-(X1 + C, Y1 + (C * A / B))
Loop Until C >= A And C >= B
A = X3 - X2
B = Y3 - Y2
Do
d = d + 10
Line (X2, Y2)-(X2 + d, Y2 + (d * A / B))
Loop Until d >= A And d >= B
Label1.Caption = "Seleccione el punto de origen."
End If
End Sub

Sólo me salen cosas raras.