Reintroduce an old bugture: use localizer as dme

Our nav.dat.gz seem to have many bugs regarding paired LOC/DME where
the DME is missing.

A feature has recently been introduced to always use a LOC frequency
as a DME to avoid these issues. However many LOC station do not have
a DME paired at their frequency and this behaviour might be as confusing
as having no DME where one should be.
Before we get new/bugfree navdata, a property can be set to select
the desired behaviour:

if /sim/realism/dme-fallback-to-loc is true or absent, LOC will be
treated as DME (realism is off)
if /sim/realism/dme-fallback-to-loc is false, LOC will be NOT be
treated as DME (realism is on)

diff --git a/src/Instrumentation/dme.cxx b/src/Instrumentation/dme.cxx
index d8d14a5a22078598760ce44a68bbb8bd3bdd0b96..bcea965d83b596c766f49a772f4d50406e6f428b 100644 (file)
--- a/src/Instrumentation/dme.cxx
+++ b/src/Instrumentation/dme.cxx
@@ -119,8 +119,17 @@ DME::update (double delta_time_sec)
     if (_time_before_search_sec < 0) {
         _time_before_search_sec = 1.0;
 
-        _navrecord = globals->get_dmelist()->findByFreq( frequency_mhz,
-            globals->get_aircraft_position());
+        if( fgGetBool( "/sim/realism/dme-fallback-to-loc", true ) ) {
+            if( NULL == (_navrecord = globals->get_loclist()->findByFreq( frequency_mhz,
+                globals->get_aircraft_position())) ) {
+
+                _navrecord = globals->get_dmelist()->findByFreq( frequency_mhz,
+                    globals->get_aircraft_position());
+            }
+        } else {
+            _navrecord = globals->get_dmelist()->findByFreq( frequency_mhz,
+                globals->get_aircraft_position());
+        }
     }
 
     // If it's off, don't bother.