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Route manager current waypoint altitude  Topic is solved

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Route manager current waypoint altitude

Postby Octal450 » Sat Feb 25, 2017 12:57 am

Hello
Again I have a question about this Route Manager...

For my VNAV system, I need to find the altitude for the CURRENT waypoint, not wp[1] or wp[2]. Inside /autopilot/route-manager/wp is listed the current waypoint infos, but missing altitude. Inside /autopilot/route-manager/route/wp[x] I find the altitude property, but those numbers in [x] correspond to different Waypoint IDs, so I can't getprop it... Unless I can somehow put a variable with it's value in the middle of the 2 parts of property... I tried this, but this isn't the right way to do it. But perhaps, it will allow you to understand what I mean. \

Code: Select all
var wpnum = "1";
getprop("/autopilot/route-manager/route/wp["wpnum"]/altitude-ft");


I wish route manager forwarded all waypoint props into the current waypoint selection...
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Re: Route manager current waypoint altitude  

Postby tikibar » Sat Feb 25, 2017 1:44 am

The route manager gives you "autopilot/route-manager/current-wp." You can use that to access the altitude.

Code: Select all
var wp_curr = getprop("autopilot/route-manager/current-wp");
var alt_curr_wp = getprop("autopilot/route-manager/route/wp["~wp_curr~"]/altitude-ft");
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Re: Route manager current waypoint altitude

Postby Octal450 » Sat Feb 25, 2017 3:33 am

Ahh perfect tikibar!

Thanks for much!

Josh
Last edited by Octal450 on Sat Feb 25, 2017 5:42 pm, edited 1 time in total.
What I do: Flight Dynamics, Systems, Canvas Displays, Autoflight, FlyByWire, Cockpit Animations
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Re: Route manager current waypoint altitude

Postby zakalawe » Sat Feb 25, 2017 4:43 pm

Please use Nasal API access functions to access this, not the property tree. This is much more efficient than constructing the property path.
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Re: Route manager current waypoint altitude

Postby Hooray » Sat Feb 25, 2017 4:58 pm

zakalawe wrote in Sat Feb 25, 2017 4:43 pm:Please use Nasal API access functions to access this, not the property tree. This is much more efficient than constructing the property path.

The last comment isn't necessarily quite correct in the case of the posted snippet, because string concatenation in Nasal space can be avoided by using indexed getprop calls, which ultimately means fewer Nasal operands on the opcode stack (and context switches) than doing a C extension API call to query the navcache, e.g. consider using this:

Code: Select all
var alt_curr_wp = getprop("autopilot/route-manager/route/wp",wp_curr,"altitude-ft");


For details, see: http://wiki.flightgear.org/Nasal_library#getprop.28.29

Note: This was implemented by Philosopher a few years ago and committed by Zakalawe.
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Re: Route manager current waypoint altitude

Postby Octal450 » Sat Feb 25, 2017 5:42 pm

Noted.

Compatibility isn't an issue since ITAF is support in FGFS versions 2016.1.1 and later only. (It could work in earlier, but I don't provide support/help/instructions).

Thanks,
Josh
What I do: Flight Dynamics, Systems, Canvas Displays, Autoflight, FlyByWire, Cockpit Animations
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