Co-ordinates of a point on a line [resolved by beachbum]

[Guru]

I've got a line (control) on a form

The line can be anywhere and at any angle. ie x1 can be > or < x2 and y1 can be > or < y2.

I want to calculate the co-ordinates of a point on the line 1/4 of the way along from the x1,y1 end.

I reckon the easiest way is to convert to polar co-ordinates and back again.

any other suggestions?

[beachbum]

Hi
Finding a position on a line is simply a matter of using y = mx + b. Here is some code for u to play around with

Form contains
Picture1 picture box
Line1, Line2, Line3 inside of Picture 1 'For effect change colour of Line1
Command1 button outside of picture1

Private Sub Command1_Click()
    Randomize
    Picture1.Scale (0, 1000)-(1000, 0)'Any scaling will work
    With Line1
        .X1 = Int(Rnd * 1001)'Set initial line coords
        .X2 = Int(Rnd * 1001)
        .Y1 = Int(Rnd * 1001)
        .Y2 = Int(Rnd * 1001)
    End With
    
    'Find quarter way position from x1
    With Line1: Line2.X1 = (.X2 - .X1) \ 4 + .X1: End With
    With Line2: .X2 = .X1: .Y1 = 0: .Y2 = 1000: End With
    'Get angle of line and add y coords ie Y = mx + b
    With Line1: Line3.Y1 = (.Y2 - .Y1) / (.X2 - .X1) * (Line2.X1 - .X1) + .Y1: End With
    With Line3: .Y2 = .Y1: .X1 = 0: .X2 = 1000: End With
End Sub

[Guru]

Thanks beachbum

perfect!