X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FMain%2Ffg_props.cxx;h=2c93ad36cb47de433224de253cadc54726b0239e;hb=09d4176e963be04dec40943083e369081b8f7a18;hp=0b3285e33de7c1c7ee85139372fe9bfc516eff67;hpb=a0cabcd2af714c7d338153554e23930cdb6ee004;p=flightgear.git

diff --git a/src/Main/fg_props.cxx b/src/Main/fg_props.cxx
index 0b3285e33..2c93ad36c 100644
--- a/src/Main/fg_props.cxx
+++ b/src/Main/fg_props.cxx
@@ -24,98 +24,35 @@
 #  include <simgear/compiler.h>
 #endif
 
-#include <simgear/misc/exception.hxx>
+#include <simgear/structure/exception.hxx>
+#include <simgear/magvar/magvar.hxx>
+#include <simgear/timing/sg_time.hxx>
+#include <simgear/misc/sg_path.hxx>
+#include <simgear/scene/material/matlib.hxx>
+#include <simgear/sound/soundmgr_openal.hxx>
 
 #include STL_IOSTREAM
 
 #include <ATC/ATCdisplay.hxx>
-#include <Autopilot/newauto.hxx>
 #include <Aircraft/aircraft.hxx>
 #include <Time/tmp.hxx>
 #include <FDM/UIUCModel/uiuc_aircraftdir.h>
-#ifndef FG_OLD_WEATHER
-#  include <WeatherCM/FGLocalWeatherDatabase.h>
-#else
-#  include <Weather/weather.hxx>
-#endif
-#include <Objects/matlib.hxx>
+#include <Environment/environment.hxx>
 
 #include <GUI/gui.h>
 
 #include "globals.hxx"
-#include "fgfs.hxx"
 #include "fg_props.hxx"
-#include "viewmgr.hxx"
 
-#if !defined(SG_HAVE_NATIVE_SGI_COMPILERS)
 SG_USING_STD(istream);
 SG_USING_STD(ostream);
-#endif
-
-static double getWindNorth ();
-static double getWindEast ();
-static double getWindDown ();
-
-// Allow the view to be set from two axes (i.e. a joystick hat)
-// This needs to be in FGViewer itself, somehow.
-static double axisLong = 0.0;
-static double axisLat = 0.0;
 
 static bool winding_ccw = true; // FIXME: temporary
 
 static bool fdm_data_logging = false; // FIXME: temporary
 
+static bool frozen = false;	// FIXME: temporary
 
-/**
- * Utility function.
- */
-static inline void
-_set_view_from_axes ()
-{
-				// Take no action when hat is centered
-  if ( ( axisLong <  0.01 ) &&
-       ( axisLong > -0.01 ) &&
-       ( axisLat  <  0.01 ) &&
-       ( axisLat  > -0.01 )
-     )
-    return;
-
-  double viewDir = 999;
-
-  /* Do all the quick and easy cases */
-  if (axisLong < 0) {		// Longitudinal axis forward
-    if (axisLat == axisLong)
-      viewDir = 45;
-    else if (axisLat == - axisLong)
-      viewDir = 315;
-    else if (axisLat == 0)
-      viewDir = 0;
-  } else if (axisLong > 0) {	// Longitudinal axis backward
-    if (axisLat == - axisLong)
-      viewDir = 135;
-    else if (axisLat == axisLong)
-      viewDir = 225;
-    else if (axisLat == 0)
-      viewDir = 180;
-  } else if (axisLong == 0) {	// Longitudinal axis neutral
-    if (axisLat < 0)
-      viewDir = 90;
-    else if (axisLat > 0)
-      viewDir = 270;
-    else return; /* And assertion failure maybe? */
-  }
-
-  /* Do all the difficult cases */
-  if ( viewDir > 900 )
-    viewDir = SGD_RADIANS_TO_DEGREES * atan2 ( -axisLat, -axisLong );
-  if ( viewDir < -1 ) viewDir += 360;
-
-//  SG_LOG(SG_INPUT, SG_ALERT, "Joystick Lat=" << axisLat << "   and Long="
-//	<< axisLong << "  gave angle=" << viewDir );
-
-  globals->get_current_view()->set_goal_view_offset(viewDir*SGD_DEGREES_TO_RADIANS);
-//   globals->get_current_view()->set_view_offset(viewDir*SGD_DEGREES_TO_RADIANS);
-}
 
 
 ////////////////////////////////////////////////////////////////////////
@@ -152,23 +89,24 @@ LogClassMapping log_class_mappings [] = {
 /**
  * Get the logging classes.
  */
-static string
+static const char *
 getLoggingClasses ()
 {
   sgDebugClass classes = logbuf::get_log_classes();
-  string result = "";
+  static string result = "";	// FIXME
   for (int i = 0; log_class_mappings[i].c != SG_UNDEFD; i++) {
     if ((classes&log_class_mappings[i].c) > 0) {
-      if (result != (string)"")
+      if (!result.empty())
 	result += '|';
       result += log_class_mappings[i].name;
     }
   }
-  return result;
+  return result.c_str();
 }
 
 
-static void addLoggingClass (const string &name)
+static void
+addLoggingClass (const string &name)
 {
   sgDebugClass classes = logbuf::get_log_classes();
   for (int i = 0; log_class_mappings[i].c != SG_UNDEFD; i++) {
@@ -177,7 +115,7 @@ static void addLoggingClass (const string &name)
       return;
     }
   }
-  SG_LOG(SG_GENERAL, SG_ALERT, "Unknown logging class: " << name);
+  SG_LOG(SG_GENERAL, SG_WARN, "Unknown logging class: " << name);
 }
 
 
@@ -185,8 +123,9 @@ static void addLoggingClass (const string &name)
  * Set the logging classes.
  */
 static void
-setLoggingClasses (string classes)
+setLoggingClasses (const char * c)
 {
+  string classes = c;
   logbuf::set_log_classes(SG_NONE);
 
   if (classes == "none") {
@@ -194,7 +133,7 @@ setLoggingClasses (string classes)
     return;
   }
 
-  if (classes == "" || classes == "all") { // default
+  if (classes.empty() || classes == "all") { // default
     logbuf::set_log_classes(SG_ALL);
     SG_LOG(SG_GENERAL, SG_INFO, "Enabled all logging classes: "
 	   << getLoggingClasses());
@@ -219,7 +158,7 @@ setLoggingClasses (string classes)
 /**
  * Get the logging priority.
  */
-static string
+static const char *
 getLoggingPriority ()
 {
   switch (logbuf::get_log_priority()) {
@@ -245,13 +184,16 @@ getLoggingPriority ()
  * Set the logging priority.
  */
 static void
-setLoggingPriority (string priority)
+setLoggingPriority (const char * p)
 {
+  if (p == 0)
+      return;
+  string priority = p;
   if (priority == "bulk") {
     logbuf::set_log_priority(SG_BULK);
   } else if (priority == "debug") {
     logbuf::set_log_priority(SG_DEBUG);
-  } else if (priority == "" || priority == "info") { // default
+  } else if (priority.empty() || priority == "info") { // default
     logbuf::set_log_priority(SG_INFO);
   } else if (priority == "warn") {
     logbuf::set_log_priority(SG_WARN);
@@ -260,44 +202,47 @@ setLoggingPriority (string priority)
   } else {
     SG_LOG(SG_GENERAL, SG_WARN, "Unknown logging priority " << priority);
   }
-  SG_LOG(SG_GENERAL, SG_INFO, "Logging priority is " << getLoggingPriority());
+  SG_LOG(SG_GENERAL, SG_DEBUG, "Logging priority is " << getLoggingPriority());
 }
 
 
 /**
- * Get the pause state of the sim.
+ * Return the current frozen state.
  */
 static bool
 getFreeze ()
 {
-  return globals->get_freeze();
+  return frozen;
 }
 
 
 /**
- * Set the pause state of the sim.
+ * Set the current frozen state.
  */
 static void
-setFreeze (bool freeze)
+setFreeze (bool f)
 {
-    globals->set_freeze(freeze);
-    if ( freeze ) {
-        // BusyCursor( 0 );
-        current_atcdisplay->CancelRepeatingMessage();
-        current_atcdisplay->RegisterRepeatingMessage("****    SIM IS FROZEN    ****    SIM IS FROZEN    ****");
-    } else {
-        // BusyCursor( 1 );
-        current_atcdisplay->CancelRepeatingMessage();
+    frozen = f;
+
+    // Stop sound on a pause
+    SGSoundMgr *s = globals->get_soundmgr();
+    if ( s != NULL ) {
+        if ( f ) {
+            s->pause();
+        } else {
+            s->resume();
+        }
     }
 }
 
+
 /**
  * Return the current aircraft directory (UIUC) as a string.
  */
-static string 
+static const char *
 getAircraftDir ()
 {
-  return aircraft_dir;
+  return aircraft_dir.c_str();
 }
 
 
@@ -305,124 +250,34 @@ getAircraftDir ()
  * Set the current aircraft directory (UIUC).
  */
 static void
-setAircraftDir (string dir)
+setAircraftDir (const char * dir)
 {
-  if (getAircraftDir() != dir) {
-    aircraft_dir = dir;
-//     needReinit(); FIXME!!
-  }
+  aircraft_dir = dir;
 }
 
 
 /**
- * Get the current view offset in degrees.
+ * Return the number of milliseconds elapsed since simulation started.
  */
 static double
-getViewOffset ()
-{
-  return (globals->get_current_view()
-	  ->get_view_offset() * SGD_RADIANS_TO_DEGREES);
-}
-
-
-static void
-setViewOffset (double offset)
+getElapsedTime_sec ()
 {
-  globals->get_current_view()->set_view_offset(offset * SGD_DEGREES_TO_RADIANS);
-}
-
-static double
-getGoalViewOffset ()
-{
-  return (globals->get_current_view()
-	  ->get_goal_view_offset() * SGD_RADIANS_TO_DEGREES);
-}
-
-static void
-setGoalViewOffset (double offset)
-{
-    while ( offset < 0 ) {
-	offset += 360.0;
-    }
-    while ( offset > 360.0 ) {
-	offset -= 360.0;
-    }
-    // Snap to center if we are close
-    if ( fabs(offset) < 1.0 ||  fabs(offset) > 359.0 ) {
-	offset = 0.0;
-    }
-
-    globals->get_current_view()
-	->set_goal_view_offset(offset * SGD_DEGREES_TO_RADIANS);
-}
-
-
-/**
- * Pilot position offset from CG.
- */
-static float
-getPilotPositionXOffset ()
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  return offset[0];
-}
-
-static void
-setPilotPositionXOffset (float x)
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  pilot_view->set_pilot_offset(x, offset[1], offset[2]);
-}
-
-static float
-getPilotPositionYOffset ()
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  return offset[1];
-}
-
-static void
-setPilotPositionYOffset (float y)
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  pilot_view->set_pilot_offset(offset[0], y, offset[2]);
-}
-
-static float
-getPilotPositionZOffset ()
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  return offset[2];
-}
-
-static void
-setPilotPositionZOffset (float z)
-{
-  FGViewer * pilot_view = globals->get_viewmgr()->get_view(0);
-  float * offset = pilot_view->get_pilot_offset();
-  pilot_view->set_pilot_offset(offset[0], offset[1], z);
+  return globals->get_sim_time_sec();
 }
 
 
 /**
  * Return the current Zulu time.
  */
-static string 
+static const char *
 getDateString ()
 {
-  string out;
-  char buf[64];
+  static char buf[64];		// FIXME
   struct tm * t = globals->get_time_params()->getGmt();
   sprintf(buf, "%.4d-%.2d-%.2dT%.2d:%.2d:%.2d",
 	  t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
 	  t->tm_hour, t->tm_min, t->tm_sec);
-  out = buf;
-  return out;
+  return buf;
 }
 
 
@@ -430,15 +285,18 @@ getDateString ()
  * Set the current Zulu time.
  */
 static void
-setDateString (string date_string)
+setDateString (const char * date_string)
 {
+  static const SGPropertyNode *cur_time_override
+	= fgGetNode("/sim/time/cur-time-override", true);
+
   SGTime * st = globals->get_time_params();
   struct tm * current_time = st->getGmt();
   struct tm new_time;
 
 				// Scan for basic ISO format
 				// YYYY-MM-DDTHH:MM:SS
-  int ret = sscanf(date_string.c_str(), "%d-%d-%dT%d:%d:%d",
+  int ret = sscanf(date_string, "%d-%d-%dT%d:%d:%d",
 		   &(new_time.tm_year), &(new_time.tm_mon),
 		   &(new_time.tm_mday), &(new_time.tm_hour),
 		   &(new_time.tm_min), &(new_time.tm_sec));
@@ -448,7 +306,7 @@ setDateString (string date_string)
 				// if the save file has been edited
 				// by hand.
   if (ret != 6) {
-    SG_LOG(SG_INPUT, SG_ALERT, "Date/time string " << date_string
+    SG_LOG(SG_INPUT, SG_WARN, "Date/time string " << date_string
 	   << " not in YYYY-MM-DDTHH:MM:SS format; skipped");
     return;
   }
@@ -466,49 +324,23 @@ setDateString (string date_string)
   double lon = current_aircraft.fdm_state->get_Longitude();
   double lat = current_aircraft.fdm_state->get_Latitude();
   globals->set_warp(warp);
-  st->update(lon, lat, warp);
-  fgUpdateSkyAndLightingParams();
+  st->update(lon, lat, cur_time_override->getLongValue(), warp);
 }
 
 /**
  * Return the GMT as a string.
  */
-static string 
+static const char *
 getGMTString ()
 {
-  string out;
-  char buf[16];
-  struct tm * t = globals->get_time_params()->getGmt();
+  static char buf[16];		// FIXME
+  struct tm *t = globals->get_time_params()->getGmt();
   sprintf(buf, " %.2d:%.2d:%.2d",
 	  t->tm_hour, t->tm_min, t->tm_sec);
-  out = buf;
-  return out;
-}
-
-
-/**
- * Get the texture rendering state.
- */
-static bool
-getTextures ()
-{
-  return (material_lib.get_step() == 0);
+  // cout << t << " " << buf << endl;
+  return buf;
 }
 
-
-/**
- * Set the texture rendering state.
- */
-static void
-setTextures (bool textures)
-{
-  if (textures)
-    material_lib.set_step(0);
-  else
-    material_lib.set_step(1);
-}
-
-
 /**
  * Return the magnetic variation
  */
@@ -535,471 +367,10 @@ getMagDip ()
 static double
 getHeadingMag ()
 {
-  return current_aircraft.fdm_state->get_Psi() * SGD_RADIANS_TO_DEGREES - getMagVar();
-}
-
-
-/**
- * Return the fuel level in tank 1
- */
-static double
-getTank1Fuel ()
-{
-  return current_aircraft.fdm_state->get_Tank1Fuel();
-}
-
-static void
-setTank1Fuel ( double gals )
-{
-  current_aircraft.fdm_state->set_Tank1Fuel( gals );
-}
-
-/**
- * Return the fuel level in tank 2
- */
-static double
-getTank2Fuel ()
-{
-  return current_aircraft.fdm_state->get_Tank2Fuel();
-}
-
-static void
-setTank2Fuel ( double gals )
-{
-  current_aircraft.fdm_state->set_Tank2Fuel( gals );
-}
-
-
-/**
- * Get the autopilot altitude lock (true=on).
- */
-static bool
-getAPAltitudeLock ()
-{
-    return (current_autopilot->get_AltitudeEnabled() &&
-	    current_autopilot->get_AltitudeMode()
-	    == FGAutopilot::FG_ALTITUDE_LOCK);
-}
-
-
-/**
- * Set the autopilot altitude lock (true=on).
- */
-static void
-setAPAltitudeLock (bool lock)
-{
-  if (lock)
-    current_autopilot->set_AltitudeMode(FGAutopilot::FG_ALTITUDE_LOCK);
-  if (current_autopilot->get_AltitudeMode() == FGAutopilot::FG_ALTITUDE_LOCK)
-    current_autopilot->set_AltitudeEnabled(lock);
-}
-
-
-/**
- * Get the autopilot target altitude in feet.
- */
-static double
-getAPAltitude ()
-{
-  return current_autopilot->get_TargetAltitude() * SG_METER_TO_FEET;
-}
-
-
-/**
- * Set the autopilot target altitude in feet.
- */
-static void
-setAPAltitude (double altitude)
-{
-  current_autopilot->set_TargetAltitude( altitude * SG_FEET_TO_METER );
-}
-
-/**
- * Get the autopilot altitude lock (true=on).
- */
-static bool
-getAPGSLock ()
-{
-    return (current_autopilot->get_AltitudeEnabled() &&
-	    (current_autopilot->get_AltitudeMode()
-	     == FGAutopilot::FG_ALTITUDE_GS1));
-}
-
-
-/**
- * Set the autopilot altitude lock (true=on).
- */
-static void
-setAPGSLock (bool lock)
-{
-  if (lock)
-    current_autopilot->set_AltitudeMode(FGAutopilot::FG_ALTITUDE_GS1);
-  if (current_autopilot->get_AltitudeMode() == FGAutopilot::FG_ALTITUDE_GS1)
-    current_autopilot->set_AltitudeEnabled(lock);
-}
-
-
-/**
- * Get the autopilot terrain lock (true=on).
- */
-static bool
-getAPTerrainLock ()
-{
-    return (current_autopilot->get_AltitudeEnabled() &&
-	    (current_autopilot->get_AltitudeMode()
-	     == FGAutopilot::FG_ALTITUDE_TERRAIN));
-}
-
-
-/**
- * Set the autopilot terrain lock (true=on).
- */
-static void
-setAPTerrainLock (bool lock)
-{
-  if (lock) {
-    current_autopilot->set_AltitudeMode(FGAutopilot::FG_ALTITUDE_TERRAIN);
-    current_autopilot
-      ->set_TargetAGL(current_aircraft.fdm_state->get_Altitude_AGL() *
-		      SG_FEET_TO_METER);
-    cout << "Target AGL = "
-	 << current_aircraft.fdm_state->get_Altitude_AGL() * SG_FEET_TO_METER
-	 << endl;
-  }
-  if (current_autopilot->get_AltitudeMode() == FGAutopilot::FG_ALTITUDE_TERRAIN)
-    current_autopilot->set_AltitudeEnabled(lock);
-}
-
-
-/**
- * Get the autopilot target altitude in feet.
- */
-static double
-getAPClimb ()
-{
-  return current_autopilot->get_TargetClimbRate() * SG_METER_TO_FEET;
-}
-
-
-/**
- * Set the autopilot target altitude in feet.
- */
-static void
-setAPClimb (double rate)
-{
-    current_autopilot->set_TargetClimbRate( rate * SG_FEET_TO_METER );
-}
-
-
-/**
- * Get the autopilot heading lock (true=on).
- */
-static bool
-getAPHeadingLock ()
-{
-    return
-      (current_autopilot->get_HeadingEnabled() &&
-       current_autopilot->get_HeadingMode() == DEFAULT_AP_HEADING_LOCK);
-}
-
-
-/**
- * Set the autopilot heading lock (true=on).
- */
-static void
-setAPHeadingLock (bool lock)
-{
-  if (lock)
-    current_autopilot->set_HeadingMode(DEFAULT_AP_HEADING_LOCK);
-  if (current_autopilot->get_HeadingMode() == DEFAULT_AP_HEADING_LOCK)
-    current_autopilot->set_HeadingEnabled(lock);
-}
-
-
-/**
- * Get the autopilot heading bug in degrees.
- */
-static double
-getAPHeadingBug ()
-{
-  return current_autopilot->get_DGTargetHeading();
-}
-
-
-/**
- * Set the autopilot heading bug in degrees.
- */
-static void
-setAPHeadingBug (double heading)
-{
-  current_autopilot->set_DGTargetHeading( heading );
-}
-
-
-/**
- * Get the autopilot wing leveler lock (true=on).
- */
-static bool
-getAPWingLeveler ()
-{
-    return
-      (current_autopilot->get_HeadingEnabled() &&
-       current_autopilot->get_HeadingMode() == FGAutopilot::FG_TC_HEADING_LOCK);
-}
-
-
-/**
- * Set the autopilot wing leveler lock (true=on).
- */
-static void
-setAPWingLeveler (bool lock)
-{
-    if (lock)
-	current_autopilot->set_HeadingMode(FGAutopilot::FG_TC_HEADING_LOCK);
-    if (current_autopilot->get_HeadingMode() == FGAutopilot::FG_TC_HEADING_LOCK)
-      current_autopilot->set_HeadingEnabled(lock);
-}
-
-/**
- * Return true if the autopilot is locked to NAV1.
- */
-static bool
-getAPNAV1Lock ()
-{
-  return
-    (current_autopilot->get_HeadingEnabled() &&
-     current_autopilot->get_HeadingMode() == FGAutopilot::FG_HEADING_NAV1);
-}
-
-
-/**
- * Set the autopilot NAV1 lock.
- */
-static void
-setAPNAV1Lock (bool lock)
-{
-  if (lock)
-    current_autopilot->set_HeadingMode(FGAutopilot::FG_HEADING_NAV1);
-  if (current_autopilot->get_HeadingMode() == FGAutopilot::FG_HEADING_NAV1)
-    current_autopilot->set_HeadingEnabled(lock);
-}
-
-/**
- * Get the autopilot autothrottle lock.
- */
-static bool
-getAPAutoThrottleLock ()
-{
-  return current_autopilot->get_AutoThrottleEnabled();
-}
-
-
-/**
- * Set the autothrottle lock.
- */
-static void
-setAPAutoThrottleLock (bool lock)
-{
-  current_autopilot->set_AutoThrottleEnabled(lock);
-}
-
-
-// kludge
-static double
-getAPRudderControl ()
-{
-    if (getAPHeadingLock())
-        return current_autopilot->get_TargetHeading();
-    else
-        return globals->get_controls()->get_rudder();
-}
-
-// kludge
-static void
-setAPRudderControl (double value)
-{
-    if (getAPHeadingLock()) {
-        SG_LOG(SG_GENERAL, SG_DEBUG, "setAPRudderControl " << value );
-        value -= current_autopilot->get_TargetHeading();
-        current_autopilot->HeadingAdjust(value < 0.0 ? -1.0 : 1.0);
-    } else {
-        globals->get_controls()->set_rudder(value);
-    }
-}
-
-// kludge
-static double
-getAPElevatorControl ()
-{
-  if (getAPAltitudeLock())
-      return current_autopilot->get_TargetAltitude();
-  else
-    return globals->get_controls()->get_elevator();
-}
-
-// kludge
-static void
-setAPElevatorControl (double value)
-{
-    if (value != 0 && getAPAltitudeLock()) {
-        SG_LOG(SG_GENERAL, SG_DEBUG, "setAPElevatorControl " << value );
-        value -= current_autopilot->get_TargetAltitude();
-        current_autopilot->AltitudeAdjust(value < 0.0 ? 100.0 : -100.0);
-    } else {
-        globals->get_controls()->set_elevator(value);
-    }
-}
-
-// kludge
-static double
-getAPThrottleControl ()
-{
-  if (getAPAutoThrottleLock())
-    return 0.0;			// always resets
-  else
-    return globals->get_controls()->get_throttle(0);
-}
-
-// kludge
-static void
-setAPThrottleControl (double value)
-{
-  if (getAPAutoThrottleLock())
-    current_autopilot->AutoThrottleAdjust(value < 0.0 ? -0.01 : 0.01);
-  else
-    globals->get_controls()->set_throttle(FGControls::ALL_ENGINES, value);
-}
-
-
-/**
- * Get the current visibility (meters).
- */
-static double
-getVisibility ()
-{
-#ifndef FG_OLD_WEATHER
-  return WeatherDatabase->getWeatherVisibility();
-#else
-  return current_weather.get_visibility();
-#endif
-}
-
-
-/**
- * Set the current visibility (meters).
- */
-static void
-setVisibility (double visibility)
-{
-#ifndef FG_OLD_WEATHER
-  WeatherDatabase->setWeatherVisibility(visibility);
-#else
-  current_weather.set_visibility(visibility);
-#endif
-}
-
-/**
- * Get the current wind north velocity (feet/second).
- */
-static double
-getWindNorth ()
-{
-  return current_aircraft.fdm_state->get_V_north_airmass();
-}
-
-
-/**
- * Set the current wind north velocity (feet/second).
- */
-static void
-setWindNorth (double speed)
-{
-  current_aircraft.fdm_state
-    ->set_Velocities_Local_Airmass(speed, getWindEast(), getWindDown());
-}
-
-
-/**
- * Get the current wind east velocity (feet/second).
- */
-static double
-getWindEast ()
-{
-  return current_aircraft.fdm_state->get_V_east_airmass();
-}
-
-
-/**
- * Set the current wind east velocity (feet/second).
- */
-static void
-setWindEast (double speed)
-{
-  cout << "Set wind-east to " << speed << endl;
-  current_aircraft.fdm_state->set_Velocities_Local_Airmass(getWindNorth(),
-							   speed,
-							   getWindDown());
-}
-
-
-/**
- * Get the current wind down velocity (feet/second).
- */
-static double
-getWindDown ()
-{
-  return current_aircraft.fdm_state->get_V_down_airmass();
-}
-
-
-/**
- * Set the current wind down velocity (feet/second).
- */
-static void
-setWindDown (double speed)
-{
-  current_aircraft.fdm_state->set_Velocities_Local_Airmass(getWindNorth(),
-							   getWindEast(),
-							   speed);
-}
-
-/*
- * Set the current engine0 running flag.
- */
-static void
-setRunningFlag (bool flag)
-{
-  if ( current_aircraft.fdm_state->get_num_engines() > 0 ) {
-    current_aircraft.fdm_state->get_engine(0)->set_Running_Flag( flag );
-  }
-}
-
-/*
- * Set the current engine0 cranking flag.
- */
-//Although there is no real reason to want to tell the engine that it is cranking,
-//this is currently necessary to avoid the cranking sound being played 
-//before the engine inits.
-static void
-setCrankingFlag (bool flag)
-{
-  if ( current_aircraft.fdm_state->get_num_engines() > 0 ) {
-    current_aircraft.fdm_state->get_engine(0)->set_Cranking_Flag( flag );
-  }
-}
-
-static double
-getFOV ()
-{
-  return globals->get_current_view()->get_fov();
-}
-
-static void
-setFOV (double fov)
-{
-  if ( fov < 180 ) {
-      globals->get_current_view()->set_fov( fov );
-  }
+  double magheading;
+  magheading = current_aircraft.fdm_state->get_Psi() * SGD_RADIANS_TO_DEGREES - getMagVar();
+  if (magheading < 0) magheading += 360;
+  return magheading;
 }
 
 static long
@@ -1026,18 +397,6 @@ setWarpDelta (long delta)
   globals->set_warp_delta(delta);
 }
 
-static void
-setViewAxisLong (double axis)
-{
-  axisLong = axis;
-}
-
-static void
-setViewAxisLat (double axis)
-{
-  axisLat = axis;
-}
-
 static bool
 getWindingCCW ()
 {
@@ -1096,109 +455,94 @@ setFDMDataLogging (bool state)
 // Tie the properties.
 ////////////////////////////////////////////////////////////////////////
 
+FGProperties::FGProperties ()
+{
+}
+
+FGProperties::~FGProperties ()
+{
+}
+
 void
-fgInitProps ()
+FGProperties::init ()
+{
+}
+
+void
+FGProperties::bind ()
 {
 				// Simulation
   fgTie("/sim/logging/priority", getLoggingPriority, setLoggingPriority);
   fgTie("/sim/logging/classes", getLoggingClasses, setLoggingClasses);
-  fgTie("/sim/freeze", getFreeze, setFreeze);
+  fgTie("/sim/freeze/master", getFreeze, setFreeze);
   fgTie("/sim/aircraft-dir", getAircraftDir, setAircraftDir);
-  fgTie("/sim/view/offset-deg", getViewOffset, setViewOffset, false);
-  fgSetArchivable("/sim/view/offset-deg");
-  fgTie("/sim/view/goal-offset-deg", getGoalViewOffset, setGoalViewOffset, false);
-  fgSetArchivable("/sim/view/goal-offset-deg");
-  fgTie("/sim/view/pilot/x-offset-m",
-	getPilotPositionXOffset, setPilotPositionXOffset);
-  fgSetArchivable("/sim/view/pilot/x-offset-m");
-  fgTie("/sim/view/pilot/y-offset-m",
-	getPilotPositionYOffset, setPilotPositionYOffset);
-  fgSetArchivable("/sim/view/pilot/y-offset-m");
-  fgTie("/sim/view/pilot/z-offset-m",
-	getPilotPositionZOffset, setPilotPositionZOffset);
-  fgSetArchivable("/sim/view/pilot/z-offset-m");
+
+  fgTie("/sim/time/elapsed-sec", getElapsedTime_sec);
   fgTie("/sim/time/gmt", getDateString, setDateString);
   fgSetArchivable("/sim/time/gmt");
   fgTie("/sim/time/gmt-string", getGMTString);
-  fgTie("/sim/rendering/textures", getTextures, setTextures);
 
 				// Orientation
   fgTie("/orientation/heading-magnetic-deg", getHeadingMag);
 
-  //consumables
-  fgTie("/consumables/fuel/tank[0]/level-gal_us",
-	getTank1Fuel, setTank1Fuel, false);
-  fgSetArchivable("/consumables/fuel/tank[0]/level-gal_us");
-  fgTie("/consumables/fuel/tank[1]/level-gal_us",
-	getTank2Fuel, setTank2Fuel, false);
-  fgSetArchivable("/consumables/fuel/tank[1]/level-gal_us");
-
-				// Autopilot
-  fgTie("/autopilot/locks/altitude", getAPAltitudeLock, setAPAltitudeLock);
-  fgSetArchivable("/autopilot/locks/altitude");
-  fgTie("/autopilot/settings/altitude-ft", getAPAltitude, setAPAltitude);
-  fgSetArchivable("/autopilot/settings/altitude-ft");
-  fgTie("/autopilot/locks/glide-slope", getAPGSLock, setAPGSLock);
-  fgSetArchivable("/autopilot/locks/glide-slope");
-  fgTie("/autopilot/locks/terrain", getAPTerrainLock, setAPTerrainLock);
-  fgSetArchivable("/autopilot/locks/terrain");
-  fgTie("/autopilot/settings/climb-rate-fpm", getAPClimb, setAPClimb, false);
-  fgSetArchivable("/autopilot/settings/climb-rate-fpm");
-  fgTie("/autopilot/locks/heading", getAPHeadingLock, setAPHeadingLock);
-  fgSetArchivable("/autopilot/locks/heading");
-  fgTie("/autopilot/settings/heading-bug-deg",
-	getAPHeadingBug, setAPHeadingBug);
-  fgSetArchivable("/autopilot/settings/heading-bug-deg");
-  fgTie("/autopilot/locks/wing-leveler", getAPWingLeveler, setAPWingLeveler);
-  fgSetArchivable("/autopilot/locks/wing-leveler");
-  fgTie("/autopilot/locks/nav[0]", getAPNAV1Lock, setAPNAV1Lock);
-  fgSetArchivable("/autopilot/locks/nav[0]");
-  fgTie("/autopilot/locks/auto-throttle",
-	getAPAutoThrottleLock, setAPAutoThrottleLock);
-  fgSetArchivable("/autopilot/locks/auto-throttle");
-  fgTie("/autopilot/control-overrides/rudder",
-	getAPRudderControl, setAPRudderControl);
-  fgSetArchivable("/autopilot/control-overrides/rudder");
-  fgTie("/autopilot/control-overrides/elevator",
-	getAPElevatorControl, setAPElevatorControl);
-  fgSetArchivable("/autopilot/control-overrides/elevator");
-  fgTie("/autopilot/control-overrides/throttle",
-	getAPThrottleControl, setAPThrottleControl);
-  fgSetArchivable("/autopilot/control-overrides/throttle");
-
-				// Environment
-  fgTie("/environment/visibility-m", getVisibility, setVisibility);
-  fgSetArchivable("/environment/visibility-m");
-  fgTie("/environment/wind-north-fps", getWindNorth, setWindNorth);
-  fgSetArchivable("/environment/wind-north-fps");
-  fgTie("/environment/wind-east-fps", getWindEast, setWindEast);
-  fgSetArchivable("/environment/wind-east-fps");
-  fgTie("/environment/wind-down-fps", getWindDown, setWindDown);
-  fgSetArchivable("/environment/wind-down-fps");
-
   fgTie("/environment/magnetic-variation-deg", getMagVar);
   fgTie("/environment/magnetic-dip-deg", getMagDip);
 
-				// View
-  fgTie("/sim/field-of-view", getFOV, setFOV);
-  fgSetArchivable("/sim/field-of-view");
   fgTie("/sim/time/warp", getWarp, setWarp, false);
   fgTie("/sim/time/warp-delta", getWarpDelta, setWarpDelta);
-  fgTie("/sim/view/axes/long", (double(*)())0, setViewAxisLong);
-  fgTie("/sim/view/axes/lat", (double(*)())0, setViewAxisLat);
 
 				// Misc. Temporary junk.
   fgTie("/sim/temp/winding-ccw", getWindingCCW, setWindingCCW, false);
   fgTie("/sim/temp/full-screen", getFullScreen, setFullScreen);
   fgTie("/sim/temp/fdm-data-logging", getFDMDataLogging, setFDMDataLogging);
-	
 }
 
+void
+FGProperties::unbind ()
+{
+				// Simulation
+  fgUntie("/sim/logging/priority");
+  fgUntie("/sim/logging/classes");
+  fgUntie("/sim/freeze/master");
+  fgUntie("/sim/aircraft-dir");
+
+  fgUntie("/sim/time/elapsed-sec");
+  fgUntie("/sim/time/gmt");
+  fgUntie("/sim/time/gmt-string");
+
+				// Orientation
+  fgUntie("/orientation/heading-magnetic-deg");
+
+				// Environment
+  fgUntie("/environment/magnetic-variation-deg");
+  fgUntie("/environment/magnetic-dip-deg");
+
+  fgUntie("/sim/time/warp");
+  fgUntie("/sim/time/warp-delta");
+
+				// Misc. Temporary junk.
+  fgUntie("/sim/temp/winding-ccw");
+  fgUntie("/sim/temp/full-screen");
+  fgUntie("/sim/temp/fdm-data-logging");
+}
 
 void
-fgUpdateProps ()
+FGProperties::update (double dt)
 {
-  _set_view_from_axes();
+                                // Date and time
+    struct tm * t = globals->get_time_params()->getGmt();
+
+    fgSetInt("/sim/time/utc/year", t->tm_year + 1900);
+    fgSetInt("/sim/time/utc/month", t->tm_mon + 1);
+    fgSetInt("/sim/time/utc/day", t->tm_mday);
+    fgSetInt("/sim/time/utc/hour", t->tm_hour);
+    fgSetInt("/sim/time/utc/minute", t->tm_min);
+    fgSetInt("/sim/time/utc/second", t->tm_sec);
+
+    fgSetDouble("/sim/time/utc/day-seconds",
+                t->tm_hour * 3600 +
+                t->tm_min * 60 +
+                t->tm_sec);
 }
 
 
@@ -1212,10 +556,18 @@ fgUpdateProps ()
  * Save the current state of the simulator to a stream.
  */
 bool
-fgSaveFlight (ostream &output)
+fgSaveFlight (ostream &output, bool write_all)
 {
+
+  fgSetBool("/sim/presets/onground", false);
+  fgSetArchivable("/sim/presets/onground");
+  fgSetBool("/sim/presets/trim", false);
+  fgSetArchivable("/sim/presets/trim");
+  fgSetString("/sim/presets/speed-set", "UVW");
+  fgSetArchivable("/sim/presets/speed-set");
+
   try {
-    writeProperties(output, globals->get_props());
+    writeProperties(output, globals->get_props(), write_all);
   } catch (const sg_exception &e) {
     guiErrorMessage("Error saving flight: ", e);
     return false;
@@ -1237,6 +589,11 @@ fgLoadFlight (istream &input)
     guiErrorMessage("Error reading saved flight: ", e);
     return false;
   }
+
+  fgSetBool("/sim/presets/onground", false);
+  fgSetBool("/sim/presets/trim", false);
+  fgSetString("/sim/presets/speed-set", "UVW");
+
   copyProperties(&props, globals->get_props());
   // When loading a flight, make it the
   // new initial state.
@@ -1245,396 +602,177 @@ fgLoadFlight (istream &input)
 }
 
 
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGCondition.
-////////////////////////////////////////////////////////////////////////
-
-FGCondition::FGCondition ()
-{
-}
-
-FGCondition::~FGCondition ()
-{
-}
-
-
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGPropertyCondition.
-////////////////////////////////////////////////////////////////////////
-
-FGPropertyCondition::FGPropertyCondition (const string &propname)
-  : _node(fgGetNode(propname, true))
+bool
+fgLoadProps (const char * path, SGPropertyNode * props, bool in_fg_root)
 {
-}
+    string fullpath;
+    if (in_fg_root) {
+        SGPath loadpath(globals->get_fg_root());
+        loadpath.append(path);
+        fullpath = loadpath.str();
+    } else {
+        fullpath = path;
+    }
 
-FGPropertyCondition::~FGPropertyCondition ()
-{
+    try {
+        readProperties(fullpath, props);
+    } catch (const sg_exception &e) {
+        guiErrorMessage("Error reading properties: ", e);
+        return false;
+    }
+    return true;
 }
 
 
 
 ////////////////////////////////////////////////////////////////////////
-// Implementation of FGNotCondition.
+// Property convenience functions.
 ////////////////////////////////////////////////////////////////////////
 
-FGNotCondition::FGNotCondition (FGCondition * condition)
-  : _condition(condition)
+SGPropertyNode *
+fgGetNode (const char * path, bool create)
 {
+  return globals->get_props()->getNode(path, create);
 }
 
-FGNotCondition::~FGNotCondition ()
+SGPropertyNode * 
+fgGetNode (const char * path, int index, bool create)
 {
-  delete _condition;
+  return globals->get_props()->getNode(path, index, create);
 }
 
 bool
-FGNotCondition::test () const
+fgHasNode (const char * path)
 {
-  return !(_condition->test());
+  return (fgGetNode(path, false) != 0);
 }
 
-
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGAndCondition.
-////////////////////////////////////////////////////////////////////////
-
-FGAndCondition::FGAndCondition ()
+void
+fgAddChangeListener (SGPropertyChangeListener * listener, const char * path)
 {
+  fgGetNode(path, true)->addChangeListener(listener);
 }
 
-FGAndCondition::~FGAndCondition ()
+void
+fgAddChangeListener (SGPropertyChangeListener * listener,
+		     const char * path, int index)
 {
-  for (unsigned int i = 0; i < _conditions.size(); i++)
-    delete _conditions[i];
+  fgGetNode(path, index, true)->addChangeListener(listener);
 }
 
 bool
-FGAndCondition::test () const
+fgGetBool (const char * name, bool defaultValue)
 {
-  int nConditions = _conditions.size();
-  for (int i = 0; i < nConditions; i++) {
-    if (!_conditions[i]->test())
-      return false;
-  }
-  return true;
+  return globals->get_props()->getBoolValue(name, defaultValue);
 }
 
-void
-FGAndCondition::addCondition (FGCondition * condition)
+int
+fgGetInt (const char * name, int defaultValue)
 {
-  _conditions.push_back(condition);
+  return globals->get_props()->getIntValue(name, defaultValue);
 }
 
-
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGOrCondition.
-////////////////////////////////////////////////////////////////////////
-
-FGOrCondition::FGOrCondition ()
+int
+fgGetLong (const char * name, long defaultValue)
 {
+  return globals->get_props()->getLongValue(name, defaultValue);
 }
 
-FGOrCondition::~FGOrCondition ()
+float
+fgGetFloat (const char * name, float defaultValue)
 {
-  for (unsigned int i = 0; i < _conditions.size(); i++)
-    delete _conditions[i];
+  return globals->get_props()->getFloatValue(name, defaultValue);
 }
 
-bool
-FGOrCondition::test () const
+double
+fgGetDouble (const char * name, double defaultValue)
 {
-  int nConditions = _conditions.size();
-  for (int i = 0; i < nConditions; i++) {
-    if (_conditions[i]->test())
-      return true;
-  }
-  return false;
+  return globals->get_props()->getDoubleValue(name, defaultValue);
 }
 
-void
-FGOrCondition::addCondition (FGCondition * condition)
+const char *
+fgGetString (const char * name, const char * defaultValue)
 {
-  _conditions.push_back(condition);
+  return globals->get_props()->getStringValue(name, defaultValue);
 }
 
-
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGComparisonCondition.
-////////////////////////////////////////////////////////////////////////
-
-static int
-doComparison (const SGPropertyNode * left, const SGPropertyNode *right)
+bool
+fgSetBool (const char * name, bool val)
 {
-  switch (left->getType()) {
-  case SGPropertyNode::BOOL: {
-    bool v1 = left->getBoolValue();
-    bool v2 = right->getBoolValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  case SGPropertyNode::INT: {
-    int v1 = left->getIntValue();
-    int v2 = right->getIntValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  case SGPropertyNode::LONG: {
-    long v1 = left->getLongValue();
-    long v2 = right->getLongValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  case SGPropertyNode::FLOAT: {
-    float v1 = left->getFloatValue();
-    float v2 = right->getFloatValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  case SGPropertyNode::DOUBLE: {
-    double v1 = left->getDoubleValue();
-    double v2 = right->getDoubleValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  case SGPropertyNode::STRING: 
-  case SGPropertyNode::NONE:
-  case SGPropertyNode::UNSPECIFIED: {
-    string v1 = left->getStringValue();
-    string v2 = right->getStringValue();
-    if (v1 < v2)
-      return FGComparisonCondition::LESS_THAN;
-    else if (v1 > v2)
-      return FGComparisonCondition::GREATER_THAN;
-    else
-      return FGComparisonCondition::EQUALS;
-    break;
-  }
-  }
-  throw sg_exception("Unrecognized node type");
-  return 0;
+  return globals->get_props()->setBoolValue(name, val);
 }
 
-
-FGComparisonCondition::FGComparisonCondition (Type type, bool reverse)
-  : _type(type),
-    _reverse(reverse),
-    _left_property(0),
-    _right_property(0),
-    _right_value(0)
+bool
+fgSetInt (const char * name, int val)
 {
+  return globals->get_props()->setIntValue(name, val);
 }
 
-FGComparisonCondition::~FGComparisonCondition ()
+bool
+fgSetLong (const char * name, long val)
 {
-  delete _right_value;
+  return globals->get_props()->setLongValue(name, val);
 }
 
 bool
-FGComparisonCondition::test () const
+fgSetFloat (const char * name, float val)
 {
-				// Always fail if incompletely specified
-  if (_left_property == 0 ||
-      (_right_property == 0 && _right_value == 0))
-    return false;
-
-				// Get LESS_THAN, EQUALS, or GREATER_THAN
-  int cmp =
-    doComparison(_left_property,
-		 (_right_property != 0 ? _right_property : _right_value));
-  if (!_reverse)
-    return (cmp == _type);
-  else
-    return (cmp != _type);
+  return globals->get_props()->setFloatValue(name, val);
 }
 
-void
-FGComparisonCondition::setLeftProperty (const string &propname)
+bool
+fgSetDouble (const char * name, double val)
 {
-  _left_property = fgGetNode(propname, true);
+  return globals->get_props()->setDoubleValue(name, val);
 }
 
-void
-FGComparisonCondition::setRightProperty (const string &propname)
+bool
+fgSetString (const char * name, const char * val)
 {
-  delete _right_value;
-  _right_value = 0;
-  _right_property = fgGetNode(propname, true);
+  return globals->get_props()->setStringValue(name, val);
 }
 
 void
-FGComparisonCondition::setRightValue (const SGPropertyNode *node)
-{
-  _right_property = 0;
-  delete _right_value;
-  _right_value = new SGPropertyNode(*node);
-}
-
-
-
-////////////////////////////////////////////////////////////////////////
-// Read a condition and use it if necessary.
-////////////////////////////////////////////////////////////////////////
-
-                                // Forward declaration
-static FGCondition * readCondition (const SGPropertyNode * node);
-
-static FGCondition *
-readPropertyCondition (const SGPropertyNode * node)
-{
-  return new FGPropertyCondition(node->getStringValue());
-}
-
-static FGCondition *
-readNotCondition (const SGPropertyNode * node)
-{
-  int nChildren = node->nChildren();
-  for (int i = 0; i < nChildren; i++) {
-    const SGPropertyNode * child = node->getChild(i);
-    FGCondition * condition = readCondition(child);
-    if (condition != 0)
-      return new FGNotCondition(condition);
-  }
-  SG_LOG(SG_COCKPIT, SG_ALERT, "Panel: empty 'not' condition");
-  return 0;
-}
-
-static FGCondition *
-readAndConditions (const SGPropertyNode * node)
-{
-  FGAndCondition * andCondition = new FGAndCondition;
-  int nChildren = node->nChildren();
-  for (int i = 0; i < nChildren; i++) {
-    const SGPropertyNode * child = node->getChild(i);
-    FGCondition * condition = readCondition(child);
-    if (condition != 0)
-      andCondition->addCondition(condition);
-  }
-  return andCondition;
-}
-
-static FGCondition *
-readOrConditions (const SGPropertyNode * node)
-{
-  FGOrCondition * orCondition = new FGOrCondition;
-  int nChildren = node->nChildren();
-  for (int i = 0; i < nChildren; i++) {
-    const SGPropertyNode * child = node->getChild(i);
-    FGCondition * condition = readCondition(child);
-    if (condition != 0)
-      orCondition->addCondition(condition);
-  }
-  return orCondition;
-}
-
-static FGCondition *
-readComparison (const SGPropertyNode * node,
-		FGComparisonCondition::Type type,
-		bool reverse)
+fgSetArchivable (const char * name, bool state)
 {
-  FGComparisonCondition * condition = new FGComparisonCondition(type, reverse);
-  condition->setLeftProperty(node->getStringValue("property[0]"));
-  if (node->hasValue("property[1]"))
-    condition->setRightProperty(node->getStringValue("property[1]"));
+  SGPropertyNode * node = globals->get_props()->getNode(name);
+  if (node == 0)
+    SG_LOG(SG_GENERAL, SG_DEBUG,
+	   "Attempt to set archive flag for non-existant property "
+	   << name);
   else
-    condition->setRightValue(node->getChild("value", 0));
-
-  return condition;
+    node->setAttribute(SGPropertyNode::ARCHIVE, state);
 }
 
-static FGCondition *
-readCondition (const SGPropertyNode * node)
+void
+fgSetReadable (const char * name, bool state)
 {
-  const string &name = node->getName();
-  if (name == "property")
-    return readPropertyCondition(node);
-  else if (name == "not")
-    return readNotCondition(node);
-  else if (name == "and")
-    return readAndConditions(node);
-  else if (name == "or")
-    return readOrConditions(node);
-  else if (name == "less-than")
-    return readComparison(node, FGComparisonCondition::LESS_THAN, false);
-  else if (name == "less-than-equals")
-    return readComparison(node, FGComparisonCondition::GREATER_THAN, true);
-  else if (name == "greater-than")
-    return readComparison(node, FGComparisonCondition::GREATER_THAN, false);
-  else if (name == "greater-than-equals")
-    return readComparison(node, FGComparisonCondition::LESS_THAN, true);
-  else if (name == "equals")
-    return readComparison(node, FGComparisonCondition::EQUALS, false);
-  else if (name == "not-equals")
-    return readComparison(node, FGComparisonCondition::EQUALS, true);
+  SGPropertyNode * node = globals->get_props()->getNode(name);
+  if (node == 0)
+    SG_LOG(SG_GENERAL, SG_DEBUG,
+	   "Attempt to set read flag for non-existant property "
+	   << name);
   else
-    return 0;
-}
-
-
-
-////////////////////////////////////////////////////////////////////////
-// Implementation of FGConditional.
-////////////////////////////////////////////////////////////////////////
-
-FGConditional::FGConditional ()
-  : _condition (0)
-{
-}
-
-FGConditional::~FGConditional ()
-{
-  delete _condition;
+    node->setAttribute(SGPropertyNode::READ, state);
 }
 
 void
-FGConditional::setCondition (FGCondition * condition)
+fgSetWritable (const char * name, bool state)
 {
-  delete _condition;
-  _condition = condition;
-}
-
-bool
-FGConditional::test () const
-{
-  return ((_condition == 0) || _condition->test());
+  SGPropertyNode * node = globals->get_props()->getNode(name);
+  if (node == 0)
+    SG_LOG(SG_GENERAL, SG_DEBUG,
+	   "Attempt to set write flag for non-existant property "
+	   << name);
+  else
+    node->setAttribute(SGPropertyNode::WRITE, state);
 }
 
-
-
-// The top-level is always an implicit 'and' group
-FGCondition *
-fgReadCondition (const SGPropertyNode * node)
+void
+fgUntie (const char * name)
 {
-  return readAndConditions(node);
+  if (!globals->get_props()->untie(name))
+    SG_LOG(SG_GENERAL, SG_WARN, "Failed to untie property " << name);
 }