Thanks for your help- but I ended up using the formula from this Wikipedia article (http://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Line_defined_by_two_points):
abs((y2-y1)x-(x2-x1)y+x2*y1-y2*x1
sqrt((y2-y1)^2+(x2-x1)^2))
It still returns a divide-by-0 error for a certain distance between lines, but that can be easily rectified by doing this:
:If not(sqrt((y2-y1)^2+(x2-x1)^2
:x2+1->x2
:If 16>=abs((y2-y1)x-(x2-x1)y+x2*y1-y2*x1/sqrt((y2-y1)^2+(x2-x1)^2)) //16 because that'll be the sprite width in pixels
:"do stuff
Any idea how I would handle drawing and erasing sprites quickly? For now I'm just drawing a size-3 inverted pixel with real(7,4,X,Y,3 and then re-inverting it later to erase it, but that's obviously not going to cut it for an actual Fruit Ninja remake.