From 7a2e1be5bfd11f9e7d9c9bbdcd107336076fd809 Mon Sep 17 00:00:00 2001
From: ThorstenB <brehmt@gmail.com>
Date: Wed, 1 Dec 2010 22:57:35 +0100
Subject: [PATCH] GPWS: change default source to match all FDMs Provide another
 built-in altitude source to hook a radio-altimeter instrument

---
 src/Instrumentation/mk_viii.cxx | 22 ++++++++++++++--------
 src/Instrumentation/mk_viii.hxx |  3 ++-
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/src/Instrumentation/mk_viii.cxx b/src/Instrumentation/mk_viii.cxx
index 11846db5e..745ed6c2e 100755
--- a/src/Instrumentation/mk_viii.cxx
+++ b/src/Instrumentation/mk_viii.cxx
@@ -187,6 +187,7 @@ MK_VIII::PropertiesHandler::init ()
   mk_node(altitude) = fgGetNode("/position/altitude-ft", true);
   mk_node(altitude_agl) = fgGetNode("/position/altitude-agl-ft", true);
   mk_node(altitude_gear_agl) = fgGetNode("/position/gear-agl-ft", true);
+  mk_node(altitude_radar_agl) = fgGetNode("/instrumentation/radar-altimeter/radar-altitude-ft", true);
   mk_node(orientation_roll) = fgGetNode("/orientation/roll-deg", true);
   mk_node(asi_serviceable) = fgGetNode("/instrumentation/airspeed-indicator/serviceable", true);
   mk_node(asi_speed) = fgGetNode("/instrumentation/airspeed-indicator/indicated-speed-kt", true);
@@ -719,10 +720,7 @@ MK_VIII::ConfigurationModule::read_options_select_group_1 (int value)
 bool
 MK_VIII::ConfigurationModule::read_radio_altitude_input_select (int value)
 {
-  if (value >= 0 && value <= 2)
-    mk->io_handler.conf.use_gear_altitude = true;
-  else
-    mk->io_handler.conf.use_gear_altitude = false;
+  mk->io_handler.conf.altitude_source = value;
   return (value >= 0 && value <= 4) || (value >= 251 && value <= 255);
 }
 
@@ -1167,10 +1165,18 @@ MK_VIII::IOHandler::update_inputs ()
   if (mk_ainput_feed(radio_altitude))
     {
       double agl;
-      if (conf.use_gear_altitude)
-        agl = mk_node(altitude_gear_agl)->getDoubleValue();
-      else
-        agl = mk_node(altitude_agl)->getDoubleValue();
+      switch (conf.altitude_source)
+      {
+          case 3:
+              agl = mk_node(altitude_gear_agl)->getDoubleValue();
+              break;
+          case 4:
+              agl = mk_node(altitude_radar_agl)->getDoubleValue();
+              break;
+          default: // 0,1,2 (and any currently unsupported values)
+              agl = mk_node(altitude_agl)->getDoubleValue();
+              break;
+      }
       // Some flight models may return negative values when on the
       // ground or after a crash; do not allow them.
       mk_ainput(radio_altitude).set(SG_MAX2(0.0, agl));
diff --git a/src/Instrumentation/mk_viii.hxx b/src/Instrumentation/mk_viii.hxx
index 517ee49f1..e37fc972b 100755
--- a/src/Instrumentation/mk_viii.hxx
+++ b/src/Instrumentation/mk_viii.hxx
@@ -201,6 +201,7 @@ class MK_VIII : public SGSubsystem
       SGPropertyNode_ptr altitude;
       SGPropertyNode_ptr altitude_agl;
       SGPropertyNode_ptr altitude_gear_agl;
+      SGPropertyNode_ptr altitude_radar_agl;
       SGPropertyNode_ptr orientation_roll;
       SGPropertyNode_ptr asi_serviceable;
       SGPropertyNode_ptr asi_speed;
@@ -481,7 +482,7 @@ public:
       bool			alternate_steep_approach;
       bool			use_internal_gps;
       bool			localizer_enabled;
-      bool			use_gear_altitude;
+      int			altitude_source;
       bool			use_attitude_indicator;
     } conf;