172 lines
4.1 KiB
C
172 lines
4.1 KiB
C
// fg_constants.h -- various constant definitions
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//
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// Written by Curtis Olson, started July 1997.
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//
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// Copyright (C) 1997 Curtis L. Olson - curt@flightgear.org
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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//
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// $Id$
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#ifndef _FG_CONSTANTS_H
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#define _FG_CONSTANTS_H
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/*
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#ifndef __cplusplus
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# error This library requires C++
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#endif
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "Include/compiler.h"
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#ifdef FG_HAVE_STD_INCLUDES
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# include <cmath>
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#else
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# ifdef FG_MATH_EXCEPTION_CLASH
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# define exception C_exception
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# endif
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# include <math.h>
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#endif
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// This should be defined via autoconf in configure.in
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#ifndef VERSION
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#define VERSION "\"not defined\""
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#endif
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// Make sure PI is defined in its various forms
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// PI, only PI, and nothing but PI
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#ifdef M_PI
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# define FG_PI M_PI
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#else
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# define FG_PI 3.14159265358979323846
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#endif
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// 2 * PI
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#define FG_2PI 6.28318530717958647692
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// PI / 2
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#ifdef M_PI_2
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# define FG_PI_2 M_PI_2
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#else
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# define FG_PI_2 1.57079632679489661923
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#endif
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// PI / 4
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#define FG_PI_4 0.78539816339744830961
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#ifndef M_E
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# define M_E 2.7182818284590452354
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#endif
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// ONE_SECOND is pi/180/60/60, or about 100 feet at earths' equator
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#define ONE_SECOND 4.848136811E-6
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// Radius of Earth in kilometers at the equator. Another source had
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// 6378.165 but this is probably close enough
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#define EARTH_RAD 6378.155
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// Earth parameters for WGS 84, taken from LaRCsim/ls_constants.h
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// Value of earth radius from [8]
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#define EQUATORIAL_RADIUS_FT 20925650. // ft
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#define EQUATORIAL_RADIUS_M 6378138.12 // meter
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// Radius squared
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#define RESQ_FT 437882827922500. // ft
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#define RESQ_M 40680645877797.1344 // meter
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// Value of earth flattening parameter from ref [8]
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//
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// Note: FP = f
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// E = 1-f
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// EPS = sqrt(1-(1-f)^2)
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//
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#define FP 0.003352813178
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#define E 0.996647186
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#define EPS 0.081819221
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#define INVG 0.031080997
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// Time Related Parameters
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#define MJD0 2415020.0
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#define J2000 (2451545.0 - MJD0)
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#define SIDRATE .9972695677
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// Conversions
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// Degrees to Radians
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#define DEG_TO_RAD 0.017453292 // deg*pi/180 = rad
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// Radians to Degrees
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#define RAD_TO_DEG 57.29577951 // rad*180/pi = deg
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// Arc seconds to radians // (arcsec*pi)/(3600*180) = rad
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#define ARCSEC_TO_RAD 4.84813681109535993589e-06
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// Radians to arc seconds // (rad*3600*180)/pi = arcsec
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#define RAD_TO_ARCSEC 206264.806247096355156
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// Feet to Meters
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#define FEET_TO_METER 0.3048
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// Meters to Feet
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#define METER_TO_FEET 3.28083989501312335958
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// Meters to Nautical Miles, 1 nm = 6076.11549 feet
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#define METER_TO_NM 0.00053995680
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// Nautical Miles to Meters
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#define NM_TO_METER 1852.0000
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// Radians to Nautical Miles, 1 nm = 1/60 of a degree
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#define NM_TO_RAD 0.00029088820866572159
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// Nautical Miles to Radians
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#define RAD_TO_NM 3437.7467707849392526
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// For divide by zero avoidance, this will be close enough to zero
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#define FG_EPSILON 0.0000001
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// Timing constants for Flight Model updates
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#define DEFAULT_TIMER_HZ 20
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#define DEFAULT_MULTILOOP 6
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#define DEFAULT_MODEL_HZ (DEFAULT_TIMER_HZ * DEFAULT_MULTILOOP)
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// Field of view limits
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#define FG_FOV_MIN 0.1
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#define FG_FOV_MAX 179.9
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// Maximum nodes per tile
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#define FG_MAX_NODES 2000
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#endif // _FG_CONSTANTS_H
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