From 15cd4284fba912a7bb37a1aeece6cde5d08916a8 Mon Sep 17 00:00:00 2001
From: curt <curt>
Date: Mon, 4 Feb 2008 20:01:20 +0000
Subject: [PATCH] Roy Ovesen:

Please find attatched a new version of xmlauto.cxx.

Remove the call to build() in reinit(). This prevents build() from being
called twice when Reload Autopilot is selected from the Debug menu.

I've also added the ability to define an enabled property for the filters.
It's used like the PID controllers. If there is no enabled tag then the
filter defaults to enabled so that nothing should get broken by this change.

This ability can be used to create a filter between the output of a PID
controller and the property that it controls (a control surface). By putting
a noise spike filter between the output of a controller and the control
surface that it controls, we can simulate the limited movement rate that is
inherent in autopilot servos.
---
 src/Autopilot/xmlauto.cxx | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/Autopilot/xmlauto.cxx b/src/Autopilot/xmlauto.cxx
index 9ddcaf32b..8ab25c9b8 100644
--- a/src/Autopilot/xmlauto.cxx
+++ b/src/Autopilot/xmlauto.cxx
@@ -640,6 +640,19 @@ FGDigitalFilter::FGDigitalFilter(SGPropertyNode *node)
             name = cval;
         } else if ( cname == "debug" ) {
             debug = child->getBoolValue();
+        } else if ( cname == "enable" ) {
+            SGPropertyNode *prop = child->getChild( "prop" );
+            if ( prop != NULL ) {
+                enable_prop = fgGetNode( prop->getStringValue(), true );
+            }
+            SGPropertyNode *val = child->getChild( "value" );
+            if ( val != NULL ) {
+                enable_value = val->getStringValue();
+            }
+            SGPropertyNode *pass = child->getChild( "honor-passive" );
+            if ( pass != NULL ) {
+                honor_passive = pass->getBoolValue();
+            }
         } else if ( cname == "type" ) {
             if ( cval == "exponential" ) {
                 filterType = exponential;
@@ -670,10 +683,23 @@ FGDigitalFilter::FGDigitalFilter(SGPropertyNode *node)
 
 void FGDigitalFilter::update(double dt)
 {
-    if ( input_prop != NULL ) {
+    if ( input_prop != NULL && 
+         enable_prop != NULL && 
+         enable_prop->getStringValue() == enable_value) {
+        input.push_front(input_prop->getDoubleValue());
+        input.resize(samples + 1, 0.0);
+        if ( !enabled ) {
+            // first time being enabled, initialize output to the
+            // value of the output property to avoid bumping.
+            output.push_front(output_list[0]->getDoubleValue());
+            output.resize(1);
+        }
+
+        enabled = true;
+    } else if (enable_prop == NULL &&
+               input_prop != NULL) {
         input.push_front(input_prop->getDoubleValue());
         input.resize(samples + 1, 0.0);
-        // no sense if there isn't an input :-)
         enabled = true;
     } else {
         enabled = false;
@@ -798,7 +824,6 @@ void FGXMLAutopilot::init() {
 void FGXMLAutopilot::reinit() {
     components.clear();
     init();
-    build();
 }
 
 
-- 
2.39.5