Initial take of new environment subsystem. Configure with

--use-new-environment to active it.

src/Environment/.cvsignore

@@ -0,0 +1,3 @@
+.deps
+Makefile
+Makefile.in

src/Environment/Makefile.am

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+# libdir	= ${exec_prefix}/lib
+# lib_LTLIBRARIES = libEnvironment.la
+# libEnvironment_la_SOURCES = environment.c environment.h
+
+noinst_LIBRARIES = libEnvironment.a
+
+libEnvironment_a_SOURCES = environment.cxx environment.hxx
+
+if OLD_AUTOMAKE
+INCLUDES += -I$(top_srcdir) -I$(top_srcdir)/src
+else
+INCLUDES = -I$(top_srcdir) -I$(top_srcdir)/src
+endif

src/Environment/environment.cxx

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+// environment.cxx -- routines to model the natural environment
+//
+// Written by David Megginson, started February 2002.
+//
+// Copyright (C) 2002  David Megginson - david@megginson.com
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#ifdef HAVE_WINDOWS_H
+#  include <windows.h>                     
+#endif
+
+#include <GL/glut.h>
+#include <GL/gl.h>
+
+#include <math.h>
+
+#include <simgear/debug/logstream.hxx>
+#include <simgear/math/sg_random.h>
+
+#include <Main/fg_props.hxx>
+#include <Aircraft/aircraft.hxx>
+#include "environment.hxx"
+
+
+// This is a record containing current environment info
+FGEnvironment current_environment;
+
+
+FGEnvironment::FGEnvironment()
+  : visibility_m(32000),
+    wind_from_heading_deg(0),
+    wind_speed_kt(0),
+    wind_from_north_fps(0),
+    wind_from_east_fps(0),
+    wind_from_down_fps(0),
+    fog_exp_density(0),
+    fog_exp2_density(0)
+{
+}
+
+
+FGEnvironment::~FGEnvironment()
+{
+}
+
+
+// Initialize the environment modeling subsystem
+void FGEnvironment::init ()
+{
+    SG_LOG( SG_GENERAL, SG_INFO, "Initializing environment subsystem");
+}
+
+
+void
+FGEnvironment::bind ()
+{
+  fgTie("/environment/visibility-m", this,
+	&FGEnvironment::get_visibility_m, &FGEnvironment::set_visibility_m);
+  fgSetArchivable("/environment/visibility-m");
+  fgTie("/environment/wind-from-heading-deg", this,
+	&FGEnvironment::get_wind_from_heading_deg,
+	&FGEnvironment::set_wind_from_heading_deg);
+  fgTie("/environment/wind-speed-kt", this,
+	&FGEnvironment::get_wind_speed_kt, &FGEnvironment::set_wind_speed_kt);
+  fgTie("/environment/wind-from-north-fps", this,
+	&FGEnvironment::get_wind_from_north_fps,
+	&FGEnvironment::set_wind_from_north_fps, false);
+  fgSetArchivable("/environment/wind-from-north-fps");
+  fgTie("/environment/wind-from-east-fps", this,
+	&FGEnvironment::get_wind_from_east_fps,
+	&FGEnvironment::set_wind_from_east_fps, false);
+  fgSetArchivable("/environment/wind-from-east-fps");
+  fgTie("/environment/wind-from-down-fps", this,
+	&FGEnvironment::get_wind_from_down_fps,
+	&FGEnvironment::set_wind_from_down_fps, false);
+  fgSetArchivable("/environment/wind-from-down-fps");
+}
+
+void
+FGEnvironment::unbind ()
+{
+  fgUntie("/environment/visibility-m");
+  fgUntie("/environment/wind-from-heading-deg");
+  fgUntie("/environment/wind-speed-kt");
+  fgUntie("/environment/wind-from-north-fps");
+  fgUntie("/environment/wind-from-east-fps");
+  fgUntie("/environment/wind-from-down-fps");
+}
+
+void FGEnvironment::update (int dt)
+{
+				// FIXME: the FDMs should update themselves
+  current_aircraft.fdm_state
+    ->set_Velocities_Local_Airmass(wind_from_north_fps,
+				   wind_from_east_fps,
+				   wind_from_down_fps);
+}
+
+void
+FGEnvironment::set_visibility_m (double v)
+{
+	glMatrixMode(GL_MODELVIEW);
+	// in meters
+	visibility_m = v;
+
+        // for GL_FOG_EXP
+	fog_exp_density = -log(0.01 / visibility_m);
+
+	// for GL_FOG_EXP2
+	fog_exp2_density = sqrt( -log(0.01) ) / visibility_m;
+
+	// Set correct opengl fog density
+	glFogf (GL_FOG_DENSITY, fog_exp2_density);
+	glFogi( GL_FOG_MODE, GL_EXP2 );
+
+	// SG_LOG( SG_INPUT, SG_DEBUG, "Fog density = " << fog_density );
+	// SG_LOG( SG_INPUT, SG_INFO, 
+	//     	   "Fog exp2 density = " << fog_exp2_density );
+}
+
+void
+FGEnvironment::set_wind_from_heading_deg (double h)
+{
+  wind_from_heading_deg = h;
+  _recalc_ne();
+}
+
+void
+FGEnvironment::set_wind_speed_kt (double s)
+{
+  wind_speed_kt = s;
+  _recalc_ne();
+}
+
+void
+FGEnvironment::set_wind_from_north_fps (double n)
+{
+  wind_from_north_fps = n;
+  _recalc_hdgspd();
+}
+
+void
+FGEnvironment::set_wind_from_east_fps (double e)
+{
+  wind_from_east_fps = e;
+  _recalc_hdgspd();
+}
+
+void
+FGEnvironment::set_wind_from_down_fps (double d)
+{
+  wind_from_down_fps = d;
+  _recalc_hdgspd();
+}
+
+void
+FGEnvironment::_recalc_hdgspd ()
+{
+  double angle_rad = atan(wind_from_north_fps/wind_from_east_fps);
+  wind_from_heading_deg = angle_rad * SGD_RADIANS_TO_DEGREES;
+  if (wind_from_east_fps >= 0)
+    wind_from_heading_deg = 90 - wind_from_heading_deg;
+  else
+    wind_from_heading_deg = 270 - wind_from_heading_deg;
+  if (angle_rad == 0)
+    wind_speed_kt = fabs(wind_from_east_fps
+			 * SG_METER_TO_NM * SG_FEET_TO_METER * 3600);
+  else
+    wind_speed_kt = (wind_from_north_fps / sin(angle_rad))
+      * SG_METER_TO_NM * SG_FEET_TO_METER * 3600;
+}
+
+void
+FGEnvironment::_recalc_ne ()
+{
+  double speed_fps =
+    wind_speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET * (1.0/3600);
+
+  wind_from_north_fps = speed_fps *
+    cos(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
+  wind_from_east_fps = speed_fps *
+    sin(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
+}
+
+// end of environment.cxx
+

src/Environment/environment.hxx

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+// environment.hxx -- routines to model the natural environment.
+//
+// Written by David Megginson, started February 2002.
+//
+// Copyright (C) 2002  David Megginson - david@megginson.com
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+
+
+#ifndef _ENVIRONMENT_HXX
+#define _ENVIRONMENT_HXX
+
+#include <simgear/compiler.h>
+
+#include <GL/gl.h>
+
+#include <Main/fgfs.hxx>
+
+#ifdef SG_HAVE_STD_INCLUDES
+#  include <cmath>
+#else
+#  include <math.h>
+#endif
+
+
+/**
+ * Model the natural environment.
+ *
+ * This class models the natural environment at a specific place and
+ * time.  A separate instance is necessary for each location or time.
+ *
+ * This class should eventually move to SimGear.
+ */
+class FGEnvironment : public FGSubsystem
+{
+
+public:
+
+  FGEnvironment();
+  virtual ~FGEnvironment();
+  
+  virtual void init ();
+  virtual void bind ();
+  virtual void unbind ();
+  virtual void update (int dt);
+    
+  inline virtual double get_visibility_m () const { return visibility_m; }
+  inline virtual double get_wind_from_heading_deg () const {
+    return wind_from_heading_deg;
+  }
+  inline virtual double get_wind_speed_kt () const { return wind_speed_kt; }
+  inline virtual double get_wind_from_north_fps () const {
+    return wind_from_north_fps;
+  }
+  inline virtual double get_wind_from_east_fps () const {
+    return wind_from_east_fps;
+  }
+  inline virtual double get_wind_from_down_fps () const {
+    return wind_from_down_fps;
+  }
+
+  virtual void set_visibility_m (double v);
+  virtual void set_wind_from_heading_deg (double h);
+  virtual void set_wind_speed_kt (double s);
+  virtual void set_wind_from_north_fps (double n);
+  virtual void set_wind_from_east_fps (double e);
+  virtual void set_wind_from_down_fps (double d);
+
+private:
+
+  void _recalc_hdgspd ();
+  void _recalc_ne ();
+
+  double visibility_m;
+
+  double wind_from_heading_deg;
+  double wind_speed_kt;
+
+  double wind_from_north_fps;
+  double wind_from_east_fps;
+  double wind_from_down_fps;
+
+				// Do these belong here?
+  GLfloat fog_exp_density;
+  GLfloat fog_exp2_density;
+
+};
+
+// FIXME: move to FGGlobals.
+extern FGEnvironment current_environment;
+
+#endif // _ENVIRONMENT_HXX