SetBuffer BackBuffer()
mx# = MouseX()
my# = MouseY()
px# = mx + 100
py# = my
l# = 40.0
Repeat
Cls
mx# = MouseX()
my# = MouseY()
d# = Sqr((mx-px)^2 + (my-py)^2)
dx# = ((mx-px)/d)*l
dy# = ((my-py)/d)*l
px# = mx - dx
py# = my - dy
Line mx,my,px,py
Flip
Until KeyHit(1)
Will that do?