Reset: fix OSG stats handling

[flightgear.git] / src / Environment / atmosphere.cxx

diff --git a/src/Environment/atmosphere.cxx b/src/Environment/atmosphere.cxx
index 427a055d8146f3323ab1ed731a3dc59d3c551e41..b7130aea3e9a4a65cce7c4831cfaa49df985972c 100644 (file)
--- a/src/Environment/atmosphere.cxx
+++ b/src/Environment/atmosphere.cxx
@@ -1,3 +1,5 @@
+#include <boost/tuple/tuple.hpp>
+
 #include <simgear/math/SGMath.hxx>
 #include <simgear/debug/logstream.hxx>
 
@@ -5,6 +7,7 @@
 
 using namespace std;
 #include <iostream>
+#include <cstdio>
 
 const ISA_layer ISA_def[] = {
 //        0    1        2        3           4         5      6         7         8
@@ -21,54 +24,6 @@ ISA_layer(7,  80000,  262467,  0.88628, 0.000261718, 196.65, -76.50),
 
 const int ISA_def_size(sizeof(ISA_def) / sizeof(ISA_layer));
 
-#if 0
-// Pressure within a layer, as a function of height
-// and of layer parameters.
-// Physics model:  standard or nonstandard atmosphere,
-//  depending on what parameters you pass in.
-// Heights in meters, pressures in Pa.
-// As always, $lambda is positive in the troposphere,
-//  and zero in the first part of the stratosphere.
-// 
-double Ph_layer(
-  const double hh, 
-  const double hb, 
-  const double Pb, 
-  const double Tb, 
-  const double lambda) {
-using namespace atmodel;  
-  if (lambda) {
-//  (1/N) &:=& {g\,m_M \over \lambda\,R}
-    double N = lambda * Rgas / mm / g;
-    return Pb * pow((Tb - lambda*(hh - hb)) / Tb, 1/N);
-  } else {
-    return Pb * exp(-g * mm / Rgas / Tb * (hh - hb));
-  }
-}
-
-// Pressure as a function of height.
-// Valid below 32000 meters,
-//   i.e. troposphere and first two layers of stratosphere.
-// Does not depend on any caching; can be used to
-// *construct* caches and interpolation tables.
-//
-// Height in meters, pressure in pascals.
-
-double old_p_vs_a(const double height) {
-    using namespace atmodel;
-    if (height <= 11000.) {
-        return P_layer(height, 0.0, ISA::P0, ISA::T0, ISA::lam0);
-    } else if (height <= 20000.) {
-        return P_layer(height, 11000., 22632.06, 216.65, 0.0);
-    } else if (height <= 32000.) {
-        return P_layer(height, 20000.,  5474.89, 216.65, -0.001);
-    }
-    return 0;
-}
-
-
-#endif
-
 // Pressure within a layer, as a function of height.
 // Physics model:  standard or nonstandard atmosphere,
 //    depending on what parameters you pass in.
@@ -112,7 +67,7 @@ double T_layer (
 //  from the table: the reference height in that layer, 
 //  the lapse in that layer, and the cap (if any) for that layer 
 // (which we take from the /next/ row of the table, if any).
-tuple<double,double> PT_vs_hpt(
+pair<double,double> PT_vs_hpt(
       const double hh, 
       const double _p0,
       const double _t0
@@ -145,7 +100,7 @@ tuple<double,double> PT_vs_hpt(
       xhgt = (pp+1)->height;      
     }
     if (hh <= xhgt) {
-      return make_tuple(P_layer(hh, hgt, p0, t0, lapse),
+      return make_pair(P_layer(hh, hgt, p0, t0, lapse),
                  T_layer(hh, hgt, p0, t0, lapse));
     }
     p0 = P_layer(xhgt, hgt, p0, t0, lapse);
@@ -154,8 +109,8 @@ tuple<double,double> PT_vs_hpt(
   }
   
 // Should never get here.
-  SG_LOG(SG_GENERAL, SG_ALERT, "PT_vs_hpt: ran out of layers");
-  return make_tuple(d0,d0);
+  SG_LOG(SG_ENVIRONMENT, SG_ALERT, "PT_vs_hpt: ran out of layers for h=" << hh );
+  return make_pair(d0, d0);
 }
 
 
@@ -206,7 +161,7 @@ void FGAtmoCache::tabulate() {
 
     for (double hgt = -1000; hgt <= 32000;) {
         double press,temp;
-        make_tuple(ref(press), ref(temp)) = PT_vs_hpt(hgt);
+        boost::tie(press, temp) = PT_vs_hpt(hgt);
         a_tvs_p->addEntry(press / inHg, hgt / foot);
 
 #ifdef DEBUG_EXPORT_P_H
@@ -258,7 +213,7 @@ void FGAtmoCache::check_model() {
         using namespace atmodel;
         cache();
         double press,temp;
-        make_tuple(ref(press), ref(temp)) = PT_vs_hpt(height);
+        boost::tie(press, temp) = PT_vs_hpt(height);
         cout << "Height: " << height
              << " \tpressure: " << press << endl;
         cout << "Check:  "
@@ -268,7 +223,7 @@ void FGAtmoCache::check_model() {
 
 //////////////////////////////////////////////////////////////////////
 
-FGAltimeter::FGAltimeter() : kset(atmodel::ISA::P0), kft(0)
+FGAltimeter::FGAltimeter()
 {
     cache();
 }
@@ -296,7 +251,7 @@ double FGAtmo::QNH(const double field_elev, const double field_press) {
     double rslt =  field_press
             * pow(1. + ISA::lam0 * field_elev / ISA::T0 * prat, 1./nn);
 #if 0
-    SG_LOG(SG_GENERAL, SG_ALERT, "QNH: elev: " << field_elev
+    SG_LOG(SG_ENVIRONMENT, SG_ALERT, "QNH: elev: " << field_elev
                 << "  press: " << field_press
                 << "  prat: "  << prat
                 << "  rslt: " << rslt
@@ -306,6 +261,21 @@ double FGAtmo::QNH(const double field_elev, const double field_press) {
     return rslt;
 }
 
+// Invert the QNH calculation to get the field pressure from a metar
+// report.
+// field pressure _in pascals_ 
+//  ... caller gets to convert to inHg or millibars
+// Field elevation in m
+// Altimeter setting (QNH) in pascals
+// Valid for fields within the troposphere only.
+double FGAtmo::fieldPressure(const double field_elev, const double qnh)
+{
+    using namespace atmodel;
+    static const double nn = ISA::lam0 * Rgas / g / mm;
+    const double pratio = pow(qnh / ISA::P0, nn);
+    return ISA::P0 * pow(pratio - field_elev * ISA::lam0 / ISA::T0, 1.0 / nn);
+}
+
 void FGAltimeter::dump_stack1(const double Tref) {
     using namespace atmodel;
     const int bs(200);