Added support for <condition> elements under <enable> elements.

The old <prop> and <value> elements are still supported but ignored, if a <condition> element exists.

src/Autopilot/xmlauto.cxx

@@ -40,6 +40,12 @@
 using std::cout;
 using std::endl;
 
+static SGCondition * getCondition( SGPropertyNode * node )
+{
+   const SGPropertyNode* conditionNode = node->getChild("condition");
+   return conditionNode ? sgReadCondition(node, conditionNode) : NULL;
+}
+
 FGPIDController::FGPIDController( SGPropertyNode *node ):
     debug( false ),
     y_n( 0.0 ),
@@ -73,6 +79,8 @@ FGPIDController::FGPIDController( SGPropertyNode *node ):
         } else if ( cname == "debug" ) {
             debug = child->getBoolValue();
         } else if ( cname == "enable" ) {
+            _condition = getCondition( child );
+            if( _condition == NULL ) {
                // cout << "parsing enable" << endl;
                SGPropertyNode *prop = child->getChild( "prop" );
                if ( prop != NULL ) {
@@ -85,6 +93,7 @@ FGPIDController::FGPIDController( SGPropertyNode *node ):
                if ( val != NULL ) {
                    enable_value = val->getStringValue();
                }
+            }
             SGPropertyNode *pass = child->getChild( "honor-passive" );
             if ( pass != NULL ) {
                 honor_passive = pass->getBoolValue();
@@ -359,7 +368,8 @@ void FGPIDController::update( double dt ) {
     Ts = elapsedTime;
     elapsedTime = 0.0;
 
-    if (enable_prop != NULL && enable_prop->getStringValue() == enable_value) {
+    if (( _condition && _condition->test() ) ||
+        (enable_prop != NULL && enable_prop->getStringValue() == enable_value)) {
         if ( !enabled ) {
             // first time being enabled, seed u_n with current
             // property tree value
@@ -507,6 +517,8 @@ FGPISimpleController::FGPISimpleController( SGPropertyNode *node ):
         } else if ( cname == "debug" ) {
             debug = child->getBoolValue();
         } else if ( cname == "enable" ) {
+            _condition = getCondition( child );
+            if( _condition == NULL ) {
                // cout << "parsing enable" << endl;
                SGPropertyNode *prop = child->getChild( "prop" );
                if ( prop != NULL ) {
@@ -519,6 +531,7 @@ FGPISimpleController::FGPISimpleController( SGPropertyNode *node ):
                if ( val != NULL ) {
                    enable_value = val->getStringValue();
                }
+            }
         } else if ( cname == "input" ) {
             SGPropertyNode *prop = child->getChild( "prop" );
             if ( prop != NULL ) {
@@ -642,7 +655,8 @@ void FGPISimpleController::update( double dt ) {
     if (umax_prop != NULL)u_max = umax_prop->getDoubleValue();
     if (Kp_prop != NULL)Kp = Kp_prop->getDoubleValue();
 
-    if (enable_prop != NULL && enable_prop->getStringValue() == enable_value) {
+    if (( _condition && _condition->test() ) ||
+        (enable_prop != NULL && enable_prop->getStringValue() == enable_value)) {
         if ( !enabled ) {
             // we have just been enabled, zero out int_sum
             int_sum = 0.0;

src/Autopilot/xmlauto.hxx

@@ -44,6 +44,7 @@ using std::deque;
 
 #include <simgear/props/props.hxx>
 #include <simgear/structure/subsystem_mgr.hxx>
+#include <simgear/props/condition.hxx>
 
 #include <Main/fg_props.hxx>
 
@@ -68,6 +69,7 @@ protected:
     SGPropertyNode_ptr r_n_prop;
     double r_n_value;
     vector <SGPropertyNode_ptr> output_list;
+    SGSharedPtr<const SGCondition> _condition;
 
 public:
 
@@ -79,7 +81,8 @@ public:
       enabled( false ),
       input_prop( NULL ),
       r_n_prop( NULL ),
-      r_n_value( 0.0 )
+      r_n_value( 0.0 ),
+      _condition( NULL )
     { }
 
     virtual ~FGXMLAutoComponent() {}