Re: polygon issues

[Ethan M. <merritt@u.washington.edu>]

On Friday 17 October 2008 15:08:58 Manfred Schwarb wrote:
> > 
> > I have modified the code in CVS so that if all the polygon vertices are
> > given in screen coordinates, then it is clipped against the full canvas
> > rather than against the plot borders.
> > 
> 
> Thanks a lot, yes this will work for me.
> But this is probably quite confusing, if "set object rect" has other 
> clipping properties than "set object polygon".

Hmmm. True, they are not quite identical.

rectangles: clipped to the canvas if none of the vertices are
            given in axis coordinates.

polygons:   clipped to the canvas if all of the vertices are
            given in screen coordinates.

circles:    clipped to the plot for "plot with circles"
            clipping not reliable for "set object circle"

The only conflicting case is where an edge has one end specified in
axis coordinates and the other end specified in screen coordinates.
That seems like an unusual thing to do, at best.
If this causes a problem, we will deal with it.  Right now I don't know
whether the rectangle or the polygon scheme is better in practice.
It would be nice to have better clipping for circles; perhaps the new 
polygon clipping algorithm can be used there also.


-- 
Ethan A Merritt