- move HUDText constructor/methods to HUD.cxx

[flightgear.git] / src / Instrumentation / airspeed_indicator.cxx

diff --git a/src/Instrumentation/airspeed_indicator.cxx b/src/Instrumentation/airspeed_indicator.cxx
index 480d6dab33894c72349aa1bd9f531e248c20093e..db34f3fce6f70739b3ab29cd504f0307a6167649 100644 (file)
--- a/src/Instrumentation/airspeed_indicator.cxx
+++ b/src/Instrumentation/airspeed_indicator.cxx
@@ -1,4 +1,4 @@
-// airspeed_indicator.cxx - a regular VSI.
+// airspeed_indicator.cxx - a regular pitot-static airspeed indicator.
 // Written by David Megginson, started 2002.
 //
 // This file is in the Public Domain and comes with no warranty.
@@ -12,44 +12,69 @@
 #include <Main/util.hxx>
 
 
-AirspeedIndicator::AirspeedIndicator ()
-{
-}
+// A higher number means more responsive.
+#define RESPONSIVENESS 50.0
 
-AirspeedIndicator::~AirspeedIndicator ()
+AirspeedIndicator::AirspeedIndicator ( SGPropertyNode *node )
+    :
+    name("airspeed-indicator"),
+    num(0),
+    pitot_port("/systems/pitot"),
+    static_port("/systems/static")
 {
+    int i;
+    for ( i = 0; i < node->nChildren(); ++i ) {
+        SGPropertyNode *child = node->getChild(i);
+        string cname = child->getName();
+        string cval = child->getStringValue();
+        if ( cname == "name" ) {
+            name = cval;
+        } else if ( cname == "number" ) {
+            num = child->getIntValue();
+        } else if ( cname == "pitot-port" ) {
+            pitot_port = cval;
+        } else if ( cname == "static-port" ) {
+            static_port = cval;
+        } else {
+            SG_LOG( SG_INSTR, SG_WARN, "Error in aispeed-indicator config logic" );
+            if ( name.length() ) {
+                SG_LOG( SG_INSTR, SG_WARN, "Section = " << name );
+            }
+        }
+    }
 }
 
-void
-AirspeedIndicator::init ()
+
+AirspeedIndicator::AirspeedIndicator ( int i )
+    :
+    name("airspeed-indicator"),
+    num(0),
+    pitot_port("/systems/pitot"),
+    static_port("/systems/static")
 {
-    _serviceable_node =
-        fgGetNode("/instrumentation/airspeed-indicator/serviceable",
-                  true);
-    _total_pressure_node =
-        fgGetNode("/systems/pitot/total-pressure-inhg", true);
-    _static_pressure_node =
-        fgGetNode("/systems/static/pressure-inhg", true);
-    _speed_node =
-        fgGetNode("/instrumentation/airspeed-indicator/indicated-speed-kt",
-                  true);
+    num = i;
 }
 
-void
-AirspeedIndicator::bind ()
+AirspeedIndicator::~AirspeedIndicator ()
 {
 }
 
 void
-AirspeedIndicator::unbind ()
+AirspeedIndicator::init ()
 {
+    string branch;
+    branch = "/instrumentation/" + name;
+    pitot_port += "/total-pressure-inhg";
+    static_port += "/pressure-inhg";
+
+    SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
+    _serviceable_node = node->getChild("serviceable", 0, true);
+    _total_pressure_node = fgGetNode(pitot_port.c_str(), true);
+    _static_pressure_node = fgGetNode(static_port.c_str(), true);
+    _density_node = fgGetNode("/environment/density-slugft3", true);
+    _speed_node = node->getChild("indicated-speed-kt", 0, true);
 }
 
-
-#ifndef SEA_LEVEL_DENSITY_SLUGFG3
-# define SEA_LEVEL_DENSITY_SLUGFT3 0.002378
-#endif
-
 #ifndef FPSTOKTS
 # define FPSTOKTS 0.592484
 #endif
@@ -62,14 +87,22 @@ void
 AirspeedIndicator::update (double dt)
 {
     if (_serviceable_node->getBoolValue()) {
-        double pt = _total_pressure_node->getDoubleValue();
-        double p = _static_pressure_node->getDoubleValue();
-        double q = ( pt - p ) * INHGTOPSF;      // dynamic pressure
-
-                                // Now, reverse the equation
-        double v_fps = sqrt((2 * q) / SEA_LEVEL_DENSITY_SLUGFT3);
-
-        _speed_node->setDoubleValue(v_fps * FPSTOKTS);
+        double pt = _total_pressure_node->getDoubleValue() * INHGTOPSF;
+        double p = _static_pressure_node->getDoubleValue() * INHGTOPSF;
+        double r = _density_node->getDoubleValue();
+        double q = ( pt - p );  // dynamic pressure
+
+        // Now, reverse the equation (normalize dynamic pressure to
+        // avoid "nan" results from sqrt)
+        if ( q < 0 ) { q = 0.0; }
+        double v_fps = sqrt((2 * q) / r);
+
+                                // Publish the indicated airspeed
+        double last_speed_kt = _speed_node->getDoubleValue();
+        double current_speed_kt = v_fps * FPSTOKTS;
+        _speed_node->setDoubleValue(fgGetLowPass(last_speed_kt,
+                                                 current_speed_kt,
+                                                 dt * RESPONSIVENESS));
     }
 }