[RESOLVED] Making a Shape move along a Line

[LaVolpe]

Try this formula. Ensure you pass the distance to move in appropriate scale units of the Line's container. For simplicity, suggest just changing the line's container (form, picbox, whatever) to a ScaleMode of vbPixels. The DistanceToMove parameter is number of units from the line's X1,Y1 point. Obviously you will want to center the shape over the returned NewX,NewY coordinates.

Private Sub GetNextPoint(Path As VB.Line, DistanceToMove As Long, NewX As Single, NewY As Single)

' DistanceToMove is number of ScaleUnits (twips,pixels,etc) to move from Path's X1,Y1 properties
' NewX & NewY will be the coordinates relative to Path's X1,Y1 & DistanceToMove

Dim dx As Single, dy As Single
Dim sLen As Single

dx = Path.X2 - Path.X1
dy = Path.Y2 - Path.Y1
sLen = Sqr(dx * dx + dy * dy)

NewY = (dy * DistanceToMove) / sLen + Path.Y1
NewX = (dx * DistanceToMove) / sLen + Path.X1

End Sub

Edited: I didn't add any logic to test whether your distance exceeds the line length. You can test that yourself. Just calc the length as shown in the subroutine & ensure you don't pass a distance greater than that. Or, within the subroutine, if DistanceToMove > sLen then return Path.X2,Path.Y2 as the NewX,NewY values

As-is, the line is used just for a starting point, direction & angle, there is no stopping point in the logic. You can traverse that line in either direction at an infinite +/- DistanceToMove

After re-reading your post, shape can start at either end? This changes the logic within the subroutine. Modified below:

Private Sub GetNextPoint(Path As VB.Line, ByVal DistanceToMove As Long, StartAtX1Y1 As Boolean, _
                             NewX As Single, NewY As Single)

' DistanceToMove is number of ScaleUnits (twips,pixels,etc) to move from Path's X1,Y1 properties
' NewX & NewY will be the coordinates relative to Path's X1,Y1 & DistanceToMove
' StartAtX1Y1 is true if starting point is X1,Y1 else False if starting from X2,Y2

Dim dx As Single, dy As Single
Dim sLen As Single

    dx = Path.X2 - Path.X1
    dy = Path.Y2 - Path.Y1
    sLen = Sqr(dx * dx + dy * dy)
    If StartAtX1Y1 = False Then DistanceToMove = sLen - DistanceToMove
    NewY = (dy * DistanceToMove) / sLen + Path.Y1
    NewX = (dx * DistanceToMove) / sLen + Path.X1

End Sub