From ec0ed21b73d431ace353ebd1fcd943a909ba264a Mon Sep 17 00:00:00 2001
From: torsten <torsten>
Date: Mon, 18 May 2009 20:27:57 +0000
Subject: [PATCH] support  <abs>true</abs> for input elements. If set to true,
 the input value is filtered thru fabs() function. Defaults to false if
 absent, so there is no impact for existing configurations

---
 src/Autopilot/xmlauto.cxx | 6 +++++-
 src/Autopilot/xmlauto.hxx | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/Autopilot/xmlauto.cxx b/src/Autopilot/xmlauto.cxx
index 640664140..1da364276 100644
--- a/src/Autopilot/xmlauto.cxx
+++ b/src/Autopilot/xmlauto.cxx
@@ -74,6 +74,10 @@ void FGXMLAutoInput::parse( SGPropertyNode_ptr node, double aValue, double aOffs
         min = new FGXMLAutoInput( n );
     }
 
+    if( (n = node->getChild( "abs" )) != NULL ) {
+      abs = n->getBoolValue();
+    }
+
     SGPropertyNode *valueNode = node->getChild( "value" );
     if ( valueNode != NULL ) {
         value = valueNode->getDoubleValue();
@@ -144,7 +148,7 @@ double FGXMLAutoInput::get_value()
             value = m;
     }
     
-    return value;
+    return abs ? fabs(value) : value;
 }
 
 FGXMLAutoComponent::FGXMLAutoComponent( SGPropertyNode * node ) :
diff --git a/src/Autopilot/xmlauto.hxx b/src/Autopilot/xmlauto.hxx
index 41946fb25..df2f9d95c 100644
--- a/src/Autopilot/xmlauto.hxx
+++ b/src/Autopilot/xmlauto.hxx
@@ -52,6 +52,7 @@ using std::deque;
 class FGXMLAutoInput : public SGReferenced {
 private:
      double             value;    // The value as a constant or initializer for the property
+     bool               abs;      // return absolute value
      SGPropertyNode_ptr property; // The name of the property containing the value
      SGSharedPtr<FGXMLAutoInput> offset;   // A fixed offset, defaults to zero
      SGSharedPtr<FGXMLAutoInput> scale;    // A constant scaling factor defaults to one
@@ -63,6 +64,7 @@ public:
     FGXMLAutoInput( SGPropertyNode_ptr node = NULL, double value = 0.0, double offset = 0.0, double scale = 1.0 ) :
       property(NULL),
       value(0.0),
+      abs(false),
       offset(NULL),
       scale(NULL),
       min(NULL),