drawing dashed line using PSet

[falcore20]

Hi i was wondering how i would be able to draw a line that is dashed, or dotted using Pset. I was able to draw a line that has only one pixel break, but i need more than that. How can i implement that?

Dim d As Single
    Dim incrE As Integer
    Dim incrNE As Integer

    'Bresenham algorithm
    
    dx = x1 - x0
    dy = y1 - y0
    d = dy * 2 - dx
    incrE = dy * 2
    incrNE = (dy - dx) * 2
    x = x0
    y = y0

    PSet (x, y)

    Do While x < x1 Or y < y1
        If (d <= 0) Then
            d = d + incrE
            x = x + 1
        Else
            d = d + incrNE
            x = x + 1
            y = y + 1
        End If

    PSet (x, y)

    Loop

Any suggestions?

thanks

[ChuckB]

Hi,
I hope this helps. I haven't named the algorithm...yet! ;-)

Create a VB app, copy the Private Sub DrawLine code into your form...add 8 command buttons...and voila! Run program and click on each button...you will see line change from solid to invisible. The key is using a filter value I call 'nFilter'.

Before I draw each pixel, I check the next bit in this 8 bit binary value. If it is a 0, I draw the pixel. If the bit is 1, I don't draw anything. You can change this to 16 bit number I think...like &HF731 and change the '7' to '15' in nFilterCount>...

Private Sub DrawLine(s As Integer, t As Integer, nLength As Integer, nFilter As Integer)
  If s < 1 Then s = 100 'out of boundary stuff...limited
  If t < 1 Then t = 100
  If nLength < 1 Then nLength = 100
  If nFilter < 1 Then nFilter = &HF
  
  Dim nFilterCount As Integer 'create couple of variables
  Dim x As Integer
  
  Form1.ScaleMode = vbPixels 'set draw mode
  Form1.DrawWidth = 2
  
  For x = 0 To nLength
    a = (2 ^ nFilterCount And nFilter)
    If a = False Then
        PSet (s + x, t)
    End If
   
    nFilterCount = nFilterCount + 1
    If nFilterCount > 7 Then nFilterCount = 0
  Next x

End Sub

Private Sub Command1_Click()
  DrawLine 100, 20, 100, &H1
End Sub
Private Sub Command2_Click()
  DrawLine 100, 30, 100, &H3
End Sub
Private Sub Command3_Click()
  DrawLine 100, 40, 100, &H7
End Sub
Private Sub Command4_Click()
  DrawLine 100, 50, 100, &HF
End Sub
Private Sub Command5_Click()
  DrawLine 100, 60, 100, &H1F
End Sub
Private Sub Command6_Click()
  DrawLine 100, 70, 100, &H3F
End Sub
Private Sub Command7_Click()
  DrawLine 100, 80, 100, &H7F
End Sub
Private Sub Command8_Click()
  DrawLine 100, 90, 100, &HFF
End Sub

Regards,
ChuckB