drawing lines

[ianpaisley]

Hi,

Say if I have a line with coordinates:

(x1,y1)-(x2,y2)

This will have a beginning and an end point.

How can I have it so the line will continue on through these, points, forever, without stopping on the points? Just need it for a project I'm working on.

Thanks.

[opus]

I would calculate the coordinates at the margin of the visible field (window/form) that are "on that line". Using those draw the line from one edge of the field to the other.

Of course, you have to redo that each time you change the visible field.

[CliffPhilip]

Assuming your example would give you a 45 degree angled line, it should be fairly easy to create something like...

dim n, x1, x2, y1, y2 as integer
   x1= 1
   x2=1
   y1=2
   y2=2
 
   for n = 1 to 100   'or any number to outerspace
      me.line (x1, y1) - (x2, y2)
      x1=x2     'sets starting point to original ending point
      y1=y2
      x2=x2+n  'sets new ending point 
      y2=y2+n
   next n

For anything other than a 45 degree angle, you would have to have a calculation of the original x y changes and put that into your formula.

[MarkT]

Doing the math would be a much better way of getting there but since mine sucks, this is how I would do it.

Option Explicit
 
Private Sub Command1_Click()
    ExtendLine 1476, 1253, 3269, 2387
End Sub
 
Private Sub Form_Load()
    Me.AutoRedraw = True
    Me.Line (1476, 1253)-(3269, 2387)
End Sub
 
Private Sub ExtendLine(ByVal x1 As Integer, _
        ByVal Y1 As Integer, ByVal X2 As Integer, _
        ByVal Y2 As Integer)
Dim x As Integer
Dim y As Integer
 
    x = Abs(x1 - X2)
    y = Abs(Y1 - Y2)
    
    Do
        Me.Cls
        x1 = x1 - x
        Y1 = Y1 - y
        Me.Line (x1, Y1)-(X2, Y2)
    Loop While x1 > 0 And Y1 > 0
    
    Do
        Me.Cls
        X2 = X2 + x
        Y2 = Y2 + y
        Me.Line (x1, Y1)-(X2, Y2)
    Loop While X2 < Me.Width And Y2 < Me.Height
 
End Sub