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Scaling a property defined as a parameter

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Scaling a property defined as a parameter

Postby Dirk7589 » Fri Apr 28, 2017 5:02 pm

Hello,

I have the following property defined as a parameter
Code: Select all
<params>
      <indicated-altitude-ft>EFIS_EICAS_Unit/ADIRU_Center_altitude_msg/altitude</indicated-altitude-ft>
      <setting-inhg>instrumentation/altimeter[0]/setting-inhg</setting-inhg>
      <setting-hpa>instrumentation/altimeter[0]/setting-hpa</setting-hpa>
   </params>

Unfortunately EFIS_EICAS_Unit/ADIRU_Center_altitude_msg/altitude is in meters as opposed to feet. The tag indicated-altitude-ft is consumed later on in the file to display the altitude. Is there a way to scale my property in this file before it gets consumed? I tried using the <expression> tags inside indicated-altitude-ft without any luck. Thank you for all your help.

Sincerely,
Dirk7589
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Re: Scaling a property defined as a parameter

Postby wlbragg » Fri Apr 28, 2017 5:36 pm

I don't think you can do it in the "params" section. I've never seen it done here.
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Re: Scaling a property defined as a parameter

Postby Dirk7589 » Fri Apr 28, 2017 5:41 pm

Ok, well could I add an additional property inside the xml such as indicated-altitude-ft and have its contents populated by the scaled EFIS_EICAS_Unit/ADIRU_Center_altitude_msg/altitude property? Adding additional XML is not an issue. As it turns out I have several properties like this that need to be scaled.
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Re: Scaling a property defined as a parameter

Postby Thorsten » Fri Apr 28, 2017 5:46 pm

I usually try to compute what I need as part of the systems definition (that's JSBSim) and only pick up the final value for animation/canvas/effects (i.e. almost never use any expressions or even scale factors in the animation). Generally what you can do inside an <fcs_function> tag is pretty versatile (tables, functions,...). In the unlikely case that framerate matters, you can even clock down the channel.

For YaSim you're left with property rules which should give you pretty much the same functionality.
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