/**************************************************************************
* constants.h -- various constant definitions
*
* Written by Curtis Olson, started July 1997.
*
* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.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.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef _FG_CONSTANTS_H
#define _FG_CONSTANTS_H
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <math.h>
/* This should be defined via autoconf in configure.in */
#ifndef VERSION
#define VERSION "\"not defined\""
#endif
// Make sure PI is defined in its various forms
// PI, only PI, and nothing but PI
#ifdef M_PI
# define FG_PI M_PI
#else
# define FG_PI 3.14159265358979323846
#endif
// 2 * PI
#define FG_2PI 6.28318530717958647692
// PI / 2
#ifdef M_PI_2
# define FG_PI_2 M_PI_2
#else
# define FG_PI_2 1.57079632679489661923
#endif
// PI / 4
#define FG_PI_4 0.78539816339744830961
/* ONE_SECOND is pi/180/60/60, or about 100 feet at earths' equator */
#define ONE_SECOND 4.848136811E-6
/* Radius of Earth in kilometers at the equator. Another source had
* 6378.165 but this is probably close enough */
#define EARTH_RAD 6378.155
/* Earth parameters for WGS 84, taken from LaRCsim/ls_constants.h */
/* Value of earth radius from [8] */
#define EQUATORIAL_RADIUS_FT 20925650. /* ft */
#define EQUATORIAL_RADIUS_M 6378138.12 /* meter */
/* Radius squared */
#define RESQ_FT 437882827922500. /* ft */
#define RESQ_M 40680645877797.1344 /* meter */
/* Value of earth flattening parameter from ref [8]
*
* Note: FP = f
* E = 1-f
* EPS = sqrt(1-(1-f)^2)
*/
#define FP 0.003352813178
#define E 0.996647186
#define EPS 0.081819221
#define INVG 0.031080997
/* Time Related Parameters */
#define MJD0 2415020.0
#define J2000 (2451545.0 - MJD0)
#define SIDRATE .9972695677
/* Conversions */
/* Degrees to Radians */
#define DEG_TO_RAD 0.017453292 /* deg*pi/180 = rad */
/* Radians to Degrees */
#define RAD_TO_DEG 57.29577951 /* rad*180/pi = deg */
/* Arc seconds to radians */ /* (arcsec*pi)/(3600*180) = rad */
#define ARCSEC_TO_RAD 4.84813681109535993589e-06
/* Radians to arc seconds */ /* (rad*3600*180)/pi = arcsec */
#define RAD_TO_ARCSEC 206264.806247096355156
/* Feet to Meters */
#define FEET_TO_METER 0.3048
/* Meters to Feet */
#define METER_TO_FEET 3.28083989501312335958
/* Meters to Nautical Miles, 1 nm = 6076.11549 feet */
#define METER_TO_NM 0.00053995680
/* Nautical Miles to Meters */
#define NM_TO_METER 1852.0000
/* Radians to Nautical Miles, 1 nm = 1/60 of a degree */
#define NM_TO_RAD 0.00029088820866572159
/* Nautical Miles to Radians */
#define RAD_TO_NM 3437.7467707849392526
/* For divide by zero avoidance, this will be close enough to zero */
#define FG_EPSILON 0.0000001
/* Timing constants for Flight Model updates */
#define DEFAULT_TIMER_HZ 20
#define DEFAULT_MULTILOOP 6
#define DEFAULT_MODEL_HZ (DEFAULT_TIMER_HZ * DEFAULT_MULTILOOP)
/* Field of view limits */
#define FG_FOV_MIN 0.1
#define FG_FOV_MAX 179.9
#endif /* _FG_CONSTANTS_H */
/* $Log$
/* Revision 1.9 1998/08/24 20:02:35 curt
/* Added ONE_SECOND (in radians)
/*
* Revision 1.8 1998/07/12 03:07:13 curt
* Added #ifdef HAVE_CONFIG_H ...
*
* Revision 1.7 1998/07/08 14:36:29 curt
* Changed name of EQUATORIAL_RADIUS_KM and RESQ_KM to "M" since they were
* in meters anyways.
*
* Unified fgCartesianPoint3d and fgPolarPoint3d in a single struct called
* fgPoint3d.
*
* Revision 1.6 1998/07/03 14:36:11 curt
* Added conversion constants to fg_constants.h to assist with converting
* between various world units and coordinate systems.
* Added gl vendor/renderer/version info to general structure. Initialized
* in fg_init.cxx
*
* Revision 1.5 1998/05/17 16:56:47 curt
* Re-organized PI related constants.
*
* Revision 1.4 1998/05/16 13:03:10 curt
* Defined field of view max/min limits.
*
* Revision 1.3 1998/04/08 23:35:32 curt
* Tweaks to Gnu automake/autoconf system.
*
* Revision 1.2 1998/03/23 21:18:37 curt
* Made FG_EPSILON smaller.
*
* Revision 1.1 1998/01/27 00:46:50 curt
* prepended "fg_" on the front of these to avoid potential conflicts with
* system include files.
*
* Revision 1.3 1998/01/22 02:59:35 curt
* Changed #ifdef FILE_H to #ifdef _FILE_H
*
* Revision 1.2 1998/01/07 03:31:26 curt
* Miscellaneous tweaks.
*
* Revision 1.1 1997/12/15 21:02:15 curt
* Moved to .../FlightGear/Src/Include/
*
* Revision 1.10 1997/09/13 01:59:45 curt
* Mostly working on stars and generating sidereal time for accurate star
* placement.
*
* Revision 1.9 1997/08/22 21:34:32 curt
* Doing a bit of reorganizing and house cleaning.
*
* Revision 1.8 1997/07/31 22:52:22 curt
* Working on redoing internal coordinate systems & scenery transformations.
*
* Revision 1.7 1997/07/23 21:52:10 curt
* Put comments around the text after an #endif for increased portability.
*
* Revision 1.6 1997/07/21 14:45:01 curt
* Minor tweaks.
*
* Revision 1.5 1997/07/19 23:04:46 curt
* Added an initial weather section.
*
* Revision 1.4 1997/07/19 22:37:03 curt
* Added various PI definitions.
*
* Revision 1.3 1997/07/14 16:26:03 curt
* Testing/playing -- placed objects randomly across the entire terrain.
*
* Revision 1.2 1997/07/08 18:20:11 curt
* Working on establishing a hard ground.
*
* Revision 1.1 1997/07/07 21:02:36 curt
* Initial revision.
* */