From 2214f540e28cdd4e7c6c9409b0bc549bd93129ae Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Wed, 23 Oct 2002 16:27:30 +0000
Subject: [PATCH] Fixed the DG heading bug hold to work with the new DG
 instrumentation. It was slightly goofed up before by about the amount of the
 magnetic variation.

---
 src/Autopilot/newauto.cxx | 14 ++++++++------
 src/Autopilot/newauto.hxx |  1 +
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/Autopilot/newauto.cxx b/src/Autopilot/newauto.cxx
index a8699bf57..1e8414e2a 100644
--- a/src/Autopilot/newauto.cxx
+++ b/src/Autopilot/newauto.cxx
@@ -213,6 +213,9 @@ void FGAutopilot::init ()
     altitude_agl_node = fgGetNode("/position/altitude-agl-ft", true);
     vertical_speed_node = fgGetNode("/velocities/vertical-speed-fps", true);
     heading_node = fgGetNode("/orientation/heading-deg", true);
+    dg_heading_node
+        = fgGetNode("/instrumentation/heading-indicator/indicated-heading-deg",
+                    true);
     roll_node = fgGetNode("/orientation/roll-deg", true);
     pitch_node = fgGetNode("/orientation/pitch-deg", true);
 
@@ -484,8 +487,10 @@ FGAutopilot::update (double dt)
     // heading hold
     if ( heading_hold == true ) {
 	if ( heading_mode == FG_DG_HEADING_LOCK ) {
-	    TargetHeading = DGTargetHeading +
-	      globals->get_steam()->get_DG_err();
+            double dg_error = heading_node->getDoubleValue()
+                - dg_heading_node->getDoubleValue();
+	    TargetHeading = DGTargetHeading + dg_error;
+            // cout << "dg_error = " << dg_error << endl;
 	    while ( TargetHeading <   0.0 ) { TargetHeading += 360.0; }
 	    while ( TargetHeading > 360.0 ) { TargetHeading -= 360.0; }
 	    MakeTargetHeadingStr( TargetHeading );
@@ -887,10 +892,7 @@ void FGAutopilot::set_HeadingMode( fgAutoHeadingMode mode ) {
     heading_mode = mode;
 
     if ( heading_mode == FG_DG_HEADING_LOCK ) {
-	// set heading hold to current heading (as read from DG)
-	// ... no, leave target heading along ... just use the current
-	// heading bug value
-        //  DGTargetHeading = FGSteam::get_DG_deg();
+	// use current heading bug value
     } else if ( heading_mode == FG_TC_HEADING_LOCK ) {
 	// set autopilot to hold a zero turn (as reported by the TC)
     } else if ( heading_mode == FG_TRUE_HEADING_LOCK ) {
diff --git a/src/Autopilot/newauto.hxx b/src/Autopilot/newauto.hxx
index 4d2407016..c10ed7dff 100644
--- a/src/Autopilot/newauto.hxx
+++ b/src/Autopilot/newauto.hxx
@@ -124,6 +124,7 @@ private:
     SGPropertyNode *altitude_agl_node;
     SGPropertyNode *vertical_speed_node;
     SGPropertyNode *heading_node;
+    SGPropertyNode *dg_heading_node;
     SGPropertyNode *roll_node;
     SGPropertyNode *pitch_node;