Hi,
Christian Mayer schrieb:
Paul Surgeon schrieb:
On Saturday 15 October 2005 23:44, Ralf Gerlich wrote:
Hi,
I hope I don't say too much if I say that there is work planned on
defining taxiways by means of polylines in TaxiDraw.
That's still very restrictive. It's a step in the right direction but is still
far from what is needed. We need polygon editing and not just polylines.
Taxiways are unfortunately too full of non-parallel sides for polylines to
work properly everywhere.
How would you draw these taxiways with polylines?
The original intention was to produce both ground AI data and the
scenery representation from these polylines. The line segments and
joints should be automatically converted to an appropriate approximation
using rectangles. However placing rectangles will still be available, at
least in what I have in mind.
I'd definitely favour a new format with polygons, proper curved
centerlines, etc., but currently the X-Plane format does not support
this and we currently have no way of syncing it with Robin Peel's
database - except by generating polygons from Robin's data just the way
we're doing it now. However, I don't think that is the intention.
I'm not sure how important giving back to Robin's DB is for "the
FlightGear community" but in the OpenSource manner I'd say we should try
to find a way of not doing things twice in two communities.
Polylines should be sufficient (as long as you don't need things like
bridges, i.e. stay 2D).
To find out if you are outside (e.g. on grass) you do a line walk. I.e.
you start on the outside (e.g. from far far away) and walk on a line to
the desired position. On that walk you cound how often you've crossed a
polyline. Each time you cross it you change from outside to inside (or
the other way round).
You are probably talking about planar partitioning, where different
faces are defined by separating lines. (The only links I can find in a
quick google search on "topological maps", "planar maps" or "DCEL"
(doubly connected edge lists) are from the CGAL-manual or
non-introductory papers)
[SNIP]
Doesn't TaxiDraw already use CGAL? With CGAL you've got all that you
need for that.
TaxiDraw doesn't use CGAL currently.
Best regards,
Ralf
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