Graphics question: A challenge to guru!

[Lunatic3]

And by the way, I am sure that you can not draw a fraction of a pixel so you may not bother with CSng to draw a tiny dot. This is what I have come across so far:

For example:
DrawLine(1,1,1,1): Draws nothing
DrawLine(1,1,2,1): Draws a 2 pixel long line
DrawLine(1,1,1.5F,1): Draws 1 pixel (anything less than 0.5F and more than 0.0F. Ofcourse this is in theory. Infact it will not draw anything if you add something less than aproximately 0.002F)
DrawLine(1,1,1.51F,1): Draws a 2 pixel long line (anything more than 0.5F and less or equal to 1F)

So using your method, if you come to a x1 + CSng(0.1) and/or a y1 + CSng(0.1) that rounds up, you will have a line that is more than 1 pixel in lenght, vertically, horizontally or both.