Graphics, Figures & Tables ⇒ Place a point on a line between two nodes

[sourlife]

I have two points, let's say

Code: Select all

\rput(1,1){\circlenode{A}{A}}
\rput(4,8){\circlenode{B}{B}}
\ncline{A}{B}

and I want to place a dot, i.e. with \psdot, on the line between A and B at distance 1 unit from A.
So far I could only manage to get the midpoint of segment AB with \pmode, but how to get to an exact position on that line?

I don't have the coordinates of A and B to compute the point manually as I create those nodes with pst-tree commands.

Thanks for any advice