// constants.h -- various constant definitions // // Written by Curtis Olson, started February 2000. // Last change by Eric van den Berg, Feb 2013 // // Copyright (C) 2000 Curtis L. Olson - http://www.flightgear.org/~curt/ // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Library General Public // License as published by the Free Software Foundation; either // version 2 of the License, or (at your option) any later version. // // This library 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 // Library 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. // // $Id$ /** \file constants.h * Various constant definitions. */ #ifndef _SG_CONSTANTS_H #define _SG_CONSTANTS_H #include #include // Make sure PI is defined in its various forms #ifndef SGD_PI // remove me once FlightGear no longer uses PLIB #ifdef M_PI const double SGD_PI = M_PI; const float SG_PI = M_PI; #else const float SG_PI = 3.1415926535f; const double SGD_PI = 3.1415926535; #endif #endif // of PLIB-SG guard /** 2 * PI */ const double SGD_2PI = SGD_PI * 2.0; /** PI / 2 */ #ifdef M_PI_2 # define SGD_PI_2 M_PI_2 #else # define SGD_PI_2 1.57079632679489661923 #endif /** PI / 4 */ const double SGD_PI_4 = 0.78539816339744830961; #ifndef SGD_DEGREES_TO_RADIANS // // remove me once FlightGear no longer uses PLIB const double SGD_DEGREES_TO_RADIANS = SGD_PI / 180.0; const double SGD_RADIANS_TO_DEGREES = 180.0 / SGD_PI; const float SG_DEGREES_TO_RADIANS = SG_PI / 180.0f; const float SG_RADIANS_TO_DEGREES = 180.0f / SG_PI; #endif // of PLIB-SG guard /** \def SG_E "e" */ #ifdef M_E # define SG_E M_E #else # define SG_E 2.7182818284590452354 #endif /** pi/180/60/60, or about 100 feet at earths' equator */ #define SG_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 SG_EARTH_RAD 6378.155 // Maximum terrain elevation from sea level #define SG_MAX_ELEVATION_M 9000.0 // Earth parameters for WGS 84, taken from LaRCsim/ls_constants.h /** Value of earth radius from LaRCsim (ft) */ #define SG_EQUATORIAL_RADIUS_FT 20925650. /** Value of equatorial earth radius from LaRCsim (meter) */ #define SG_EQUATORIAL_RADIUS_M 6378138.12 /** Radius squared (ft) */ #define SG_EQ_RAD_SQUARE_FT 437882827922500. /** Radius squared (meter) */ #define SG_EQ_RAD_SQUARE_M 40680645877797.1344 /** Value of WGS84 polar earth radius (meter) */ #define SG_POLAR_RADIUS_M 6356752.3142451794975639668 // Physical Constants, SI /**mean gravity on earth */ #define SG_g0_m_p_s2 9.80665 // m/s2 /**standard pressure at SL */ #define SG_p0_Pa 101325.0 // Pa /**standard density at SL */ #define SG_rho0_kg_p_m3 1.225 // kg/m3 /**standard temperature at SL */ #define SG_T0_K 288.15 // K (=15degC) /**specific gas constant of air*/ #define SG_R_m2_p_s2_p_K 287.05 // m2/s2/K /**specific heat constant at constant pressure*/ #define SG_cp_m2_p_s2_p_K 1004.68 // m2/s2/K /**ratio of specific heats of air*/ #define SG_gamma 1.4 // =cp/cv (cp = 1004.68 m2/s2 K , cv = 717.63 m2/s2 K) /**constant beta used to calculate dynamic viscosity */ #define SG_beta_kg_p_sm_sqrK 1.458e-06 // kg/s/m/SQRT(K) /** Sutherland constant */ #define SG_S_K 110.4 // K // Conversions /** Arc seconds to radians. (arcsec*pi)/(3600*180) = rad */ #define SG_ARCSEC_TO_RAD 4.84813681109535993589e-06 /** Radians to arc seconds. (rad*3600*180)/pi = arcsec */ #define SG_RAD_TO_ARCSEC 206264.806247096355156 /** Feet to Meters */ #define SG_FEET_TO_METER 0.3048 /** Meters to Feet */ #define SG_METER_TO_FEET 3.28083989501312335958 /** Meters to Nautical Miles. 1 nm = 6076.11549 feet */ #define SG_METER_TO_NM 0.0005399568034557235 /** Nautical Miles to Meters */ #define SG_NM_TO_METER 1852.0000 /** Meters to Statute Miles. */ #define SG_METER_TO_SM 0.0006213699494949496 /** Statute Miles to Meters. */ #define SG_SM_TO_METER 1609.3412196 /** Radians to Nautical Miles. 1 nm = 1/60 of a degree */ #define SG_NM_TO_RAD 0.00029088820866572159 /** Nautical Miles to Radians */ #define SG_RAD_TO_NM 3437.7467707849392526 /** meters per second to Knots */ #define SG_MPS_TO_KT 1.9438444924406046432 /** Knots to meters per second */ #define SG_KT_TO_MPS 0.5144444444444444444 /** Feet per second to Knots */ #define SG_FPS_TO_KT 0.5924838012958962841 /** Knots to Feet per second */ #define SG_KT_TO_FPS 1.6878098571011956874 /** meters per second to Miles per hour */ #define SG_MPS_TO_MPH 2.2369362920544020312 /** meetrs per hour to Miles per second */ #define SG_MPH_TO_MPS 0.44704 /** Meters per second to Kilometers per hour */ #define SG_MPS_TO_KMH 3.6 /** Kilometers per hour to meters per second */ #define SG_KMH_TO_MPS 0.2777777777777777778 /** Pascal to Inch Mercury */ #define SG_PA_TO_INHG 0.0002952998330101010 /** Inch Mercury to Pascal */ #define SG_INHG_TO_PA 3386.388640341 /** slug/ft3 to kg/m3 */ #define SG_SLUGFT3_TO_KGPM3 515.379 /** For divide by zero avoidance, this will be close enough to zero */ #define SG_EPSILON 0.0000001 /** Highest binobj format version we know how to read/write. This starts at * 0 and can go up to 65535 */ #define SG_BINOBJ_VERSION 6 /** for backwards compatibility */ #define SG_SCENERY_FILE_FORMAT "0.4" /** Default object ranges. Overridden by /sim/rendering/static-lod/[bare|rough|detailed] **/ #define SG_OBJECT_RANGE_BARE 30000.0 #define SG_OBJECT_RANGE_ROUGH 9000.0 #define SG_OBJECT_RANGE_DETAILED 1500.0 /** Minimum expiry time of PagedLOD within the Tile. Overridden by /sim/rendering/plod-minimum-expiry-time-secs **/ #define SG_TILE_MIN_EXPIRY 180.0 /** Radius of scenery tiles in m **/ #define SG_TILE_RADIUS 14000.0 #endif // _SG_CONSTANTS_H