Martin Spott writes: > "Norman Vine" <[EMAIL PROTECTED]> wrote: > > Martin Spott writes: > >> "Norman Vine" <[EMAIL PROTECTED]> wrote: > >> > >> > This can be turned into a Polygon Algebra abstraction, > >> > >> Every piece of manually > >> refined land cover or terrain elevation could be tagged with a > >> surrounding polygon. > > > Sure sounds like "polygon algebra" to me :-) > > Okay, okay :-) > > But the maths in behind should not really be that difficult.
Robustly calculating a 2x2 determinate is probably the most exacting math involved and there are good libraries for doing this To visualise the math issues imagine 2 almost parallel lines and determine their intersection point, then ever so slightly change the angle netween them and observe the change in the location of the intersection point. then change the angle ever so slightly in the opposite sense .... For a general discussion see http://www.lahey.com/float.htm http://www2.hursley.ibm.com/decimal/ still-wondering-how-small-epsilon-is'ly yr's Norman _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
