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apt.dat version 850

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apt.dat version 850

Postby psadro_gm » Thu Aug 25, 2011 3:47 am

I'm going to open this can of worms again.

I've been playing around with terragear for quite a while, and most of my trials have hit walls. (the ole biting off more than I can chew problem). I think I have a pretty good handle on upgrading genapts to the 8.50 version, however. Most of the work can be done using the current .btg format if I preprocess the bezier curves. The only thing that would require updating .btg would be polygon offsets, to draw the line features 'above' pavement. I haven't gotten that far yet. I do have a parser handling the pavement types, and the beginnings of the taxiway stripe polys being offset from the edge.

Not seen in the screenshots is my bezier curve handling (my first attempt was brute force, and wrong). The 850 format can specify cubic and quadratic curves, and knots. I have the data in a format now that should allow me to produce accurate curves.

I'm also writing most of this with OSG, so I can see the progress as I go without loading it into flightgear. Eventually, I'll have to write out a .btg file

Here is a wireframe look at KATL:

Image

I hope to have polygon-offset working in the next couple of days (in my viewer). The distance of the stripe to the pavement edge is currently constant from the vertices. This is incorrect, as it should remain constant distance from the edge of the pavement.

Next, I'll add back the bezier subdivisions, then comes texturing.
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Re: apt.dat version 850

Postby Gijs » Thu Aug 25, 2011 9:38 am

Welcome!

Another nice step in your scenery-upgrade project (to others: see his wiki)! Being able to use the 850 format is one of my FlightGear dreams! Keep up the good work!

Cheers,
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Re: apt.dat version 850

Postby f-ojac » Fri Aug 26, 2011 9:39 am

Nice try, keep up posted !
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Re: apt.dat version 850

Postby D-EKEW » Fri Aug 26, 2011 10:17 am

to be able to handle 850 apt data would be a major step. Curved taxiways ...yeah!
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Re: apt.dat version 850

Postby psadro_gm » Fri Aug 26, 2011 1:45 pm

I fixed the offset issue for the pavement line data. At smaller angles, the stripe would get closer to the edge. Had to remember my highschool trig to fix it...

Image

Next up is actually generate the polygons for the stripe, then I can texture the pavement and stripe, to see if polygonoffset will work.
8.50 airport parser, textured roads and streams...
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Re: apt.dat version 850

Postby psadro_gm » Fri Aug 26, 2011 7:29 pm

Calling it a day for now.

Lot's of progress. I have finished the bezier curves (quad and cubic), tessellated the pavement, created triangle strips for the outer pavement markings, and set the polygon offset to limit the z fighting.

Image

Next up is:

1) only draw pavement markings when asked (all edges have them, now)
2) creating the holes in the pavement (I'm tessellating the whole outer boundary, now).
3) Set the correct altitude of each point from SRTM data
4) Try to save to .btg format to load into flightgear (without the pavement markings for now)
8.50 airport parser, textured roads and streams...
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Re: apt.dat version 850

Postby truthsolo » Fri Aug 26, 2011 7:53 pm

Very nice work, this will add a great deal of realism to FG! I am looking forward to updated airport/nav dbs (hopefully without antennas in the middle of the runways) :D
Rob — IRC: truthsolo — I used to run mpserver16.flightgear.org (Kansas City, MO)
Good hunting!
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Re: apt.dat version 850

Postby mike4lin » Sun Aug 28, 2011 9:19 am

Very good news.
Any airport builders could already get used with newer tools alike for example:
http://www.x-plane.com/blog/2011/06/new-scenery-tools-worldeditor-2-0-beta-3/
That tool is GPL'd.
I might GPL my x-plane airports (apt.dat 8.5) or is it possbile to have terragear load also non gpl sceneries?
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Re: apt.dat version 850

Postby Gijs » Sun Aug 28, 2011 9:27 am

TerraGear doesn't care about licenses. We do though. Scenery from non-GPL (compatible) sources can not be included in the official scenery. You can distribute it as an addon though...
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Re: apt.dat version 850

Postby mike4lin » Mon Aug 29, 2011 7:15 am

As far as I've seen addons could be copied into fgdata. But what about apt.dat files? Having users modifying the global apt.dat and copy scenery files would be
very annoying for multiple airports.
In X-plane custom sceneries override the global data and hence no fuzzy install needed. Am I missing something, or do we need someone to code such?
Also for ex. LSZS has already a custom scenery addon: http://digilander.libero.it/scighera_fg/models.html. If I'd decide to GPL we would have two
addons to choose at lszs.
I'll already start with: http://wiki.flightgear.org/index.php/Howto:_convert_objects_from_MSFS but wait for apt.dat 850 integration.
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Re: apt.dat version 850

Postby radi » Mon Aug 29, 2011 12:23 pm

mike4lin wrote in Mon Aug 29, 2011 7:15 am:In X-plane custom sceneries override the global data and hence no fuzzy install needed. Am I missing something, or do we need someone to code such?

AFAIU, you could have custom and stock scenery installed into different directories, and the order of paths in $FG_SCENERY determines which one is actually loaded. So if you the have custom scenery path listed first, FG should first look there for a specific tile, and fall back to standard scenery if no custom scenery is found.
OSM buildings for LOWI, EDDC
Custom scenery for VHXX YMML
Edit .stg via the FG Object Placement Tool
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Re: apt.dat version 850

Postby VaLeo » Mon Aug 29, 2011 5:27 pm

radi,

But how about in-cockpit airport map? Visual glidslope? Radio frequences?
Its all in apt.dat, and edit it is big headache.
We need feature that load small custom apt.dat files like custom stg-btg.
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Re: apt.dat version 850

Postby psadro_gm » Tue Aug 30, 2011 12:59 am

I have the pavement parser completed for closed polygons and linear features. right now. closed polys are grey and line features are yellow. I've run a few airports from the 8.5 apt.dat and all looks well (the runways are still just the primary surface, so thresholds and the side boundaries are off)

Next up is sampling the height for the verticies, (while trying to keep the linear feature polys co planer with the underlying pavement).
The converting lat,lon,height into x,y,z for inclusing in a .btg file. (and seeing lots of z fighting in the linear features, of course)
Finally, adding polygon offset to .btg format and handling this offset in the fg scene graph.

At that point, I can hopefully load an airport into fg, and try to taxi.

Here's SFO

Image
8.50 airport parser, textured roads and streams...
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Re: apt.dat version 850

Postby psadro_gm » Tue Aug 30, 2011 1:26 am

VaLeo wrote in Mon Aug 29, 2011 5:27 pm:radi,

But how about in-cockpit airport map? Visual glidslope? Radio frequences?
Its all in apt.dat, and edit it is big headache.
We need feature that load small custom apt.dat files like custom stg-btg.


Ground networks is something that bothers me as well - i'd love to tie this in to the taxiway definitions of the airport info as well.
the apt.dat I'm working with is over 82 MBs. Seems crazy that fg has to parse this file for local info.

Current design is such that when terragear parses apt.dat, the only output is polygons. Adding more info to airport information that could be stored locally in the object itself would be interesting, but I have no idea how radio freqs, ground networks, etc are handles today.
8.50 airport parser, textured roads and streams...
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Re: apt.dat version 850

Postby mike4lin » Tue Aug 30, 2011 8:42 am

psadro_gm it's coming along beautifully.

Are you using the complete apt.dat? Myself i've only cut the relevant area for ex. lsgs and only edited this in WED. My current Suisse contains several airports in one apt.dat which overrides x-plane's apt.dat as I didn't want to submit all to Robin for inclusion in the official apt.dat: http://data.x-plane.com/contact.html

By submitting it get's GPL'd, but worse, if someone makes changes your custom scenery might suddenly look weird....
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