310 lines
9.7 KiB
C++
310 lines
9.7 KiB
C++
// flight.c -- a general interface to the various flight models
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//
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// Written by Curtis Olson, started May 1997.
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//
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// Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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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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// (Log is kept at end of this file)
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#include <stdio.h>
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#include "flight.hxx"
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#include "LaRCsim.hxx"
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#include <Debug/logstream.hxx>
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#include <FDM/External/external.hxx>
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#include <FDM/LaRCsim/ls_interface.h>
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#include <Include/fg_constants.h>
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#include <Math/fg_geodesy.hxx>
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#include <Time/timestamp.hxx>
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// base_fdm_state is the internal state that is updated in integer
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// multiples of "dt". This leads to "jitter" with respect to the real
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// world time, so we introduce cur_fdm_state which is extrapolated by
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// the difference between sim time and real world time
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FGState cur_fdm_state;
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FGState base_fdm_state;
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// Extrapolate fdm based on time_offset (in usec)
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void FGState::extrapolate( int time_offset ) {
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double dt = time_offset / 1000000.0;
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cout << "extrapolating FDM by dt = " << dt << endl;
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double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
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double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
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double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
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double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
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double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
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double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
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geodetic_position_v[0] = lat;
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geocentric_position_v[0] = lat_geoc;
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geodetic_position_v[1] = lon;
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geocentric_position_v[1] = lon_geoc;
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geodetic_position_v[2] = alt;
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geocentric_position_v[2] = radius;
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}
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// Initialize the flight model parameters
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int fgFDMInit(int model, FGState& f, double dt) {
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double save_alt = 0.0;
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FG_LOG( FG_FLIGHT ,FG_INFO, "Initializing flight model" );
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base_fdm_state = f;
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if ( model == FGState::FG_SLEW ) {
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// fgSlewInit(dt);
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} else if ( model == FGState::FG_LARCSIM ) {
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// lets try to avoid really screwing up the LaRCsim model
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if ( base_fdm_state.get_Altitude() < -9000.0 ) {
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save_alt = base_fdm_state.get_Altitude();
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base_fdm_state.set_Altitude( 0.0 );
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}
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// translate FG to LaRCsim structure
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FGState_2_LaRCsim(base_fdm_state);
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// initialize LaRCsim
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fgLaRCsimInit(dt);
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FG_LOG( FG_FLIGHT, FG_INFO, "FG pos = " <<
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base_fdm_state.get_Latitude() );
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// translate LaRCsim back to FG structure
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fgLaRCsim_2_FGState(base_fdm_state);
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// but lets restore our original bogus altitude when we are done
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if ( save_alt < -9000.0 ) {
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base_fdm_state.set_Altitude( save_alt );
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}
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} else if ( model == FGState::FG_EXTERNAL ) {
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fgExternalInit(base_fdm_state);
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} else {
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FG_LOG( FG_FLIGHT, FG_WARN,
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"Unimplemented flight model == " << model );
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}
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// set valid time for this record
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base_fdm_state.stamp_time();
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f = base_fdm_state;
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return 1;
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}
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// Run multiloop iterations of the flight model
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int fgFDMUpdate(int model, FGState& f, int multiloop, int time_offset) {
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double time_step, start_elev, end_elev;
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// printf("Altitude = %.2f\n", FG_Altitude * 0.3048);
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// set valid time for this record
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base_fdm_state.stamp_time();
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time_step = (1.0 / DEFAULT_MODEL_HZ) * multiloop;
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start_elev = base_fdm_state.get_Altitude();
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if ( model == FGState::FG_SLEW ) {
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// fgSlewUpdate(f, multiloop);
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} else if ( model == FGState::FG_LARCSIM ) {
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fgLaRCsimUpdate(base_fdm_state, multiloop);
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// extrapolate position based on actual time
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// f = extrapolate_fdm( base_fdm_state, time_offset );
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f = base_fdm_state;
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} else if ( model == FGState::FG_EXTERNAL ) {
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// fgExternalUpdate(f, multiloop);
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FGTimeStamp current;
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current.stamp();
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f = base_fdm_state;
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f.extrapolate( current - base_fdm_state.get_time_stamp() );
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} else {
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FG_LOG( FG_FLIGHT, FG_WARN,
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"Unimplemented flight model == " << model );
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}
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end_elev = base_fdm_state.get_Altitude();
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if ( time_step > 0.0 ) {
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// feet per second
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base_fdm_state.set_Climb_Rate( (end_elev - start_elev) / time_step );
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}
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return 1;
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}
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// Set the altitude (force)
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void fgFDMForceAltitude(int model, double alt_meters) {
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double sea_level_radius_meters;
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double lat_geoc;
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// Set the FG variables first
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fgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
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&sea_level_radius_meters, &lat_geoc);
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base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
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base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
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(sea_level_radius_meters *
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METER_TO_FEET) );
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// additional work needed for some flight models
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if ( model == FGState::FG_LARCSIM ) {
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ls_ForceAltitude( base_fdm_state.get_Altitude() );
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}
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}
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// Set the local ground elevation
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void fgFDMSetGroundElevation(int model, double ground_meters) {
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base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
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cur_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
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}
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// $Log$
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// Revision 1.14 1999/02/01 21:33:31 curt
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// Renamed FlightGear/Simulator/Flight to FlightGear/Simulator/FDM since
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// Jon accepted my offer to do this and thought it was a good idea.
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//
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// Revision 1.13 1999/01/27 04:48:39 curt
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// Set the runway height in cur_fdm_state as well as base_fdm_state.
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//
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// Revision 1.12 1999/01/20 13:42:22 curt
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// Tweaked FDM interface.
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// Testing check sum support for NMEA serial output.
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//
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// Revision 1.11 1999/01/19 17:52:06 curt
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// Working on being able to extrapolate a new position and orientation
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// based on a position, orientation, and time offset.
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//
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// Revision 1.10 1999/01/09 13:37:32 curt
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// Convert fgTIMESTAMP to FGTimeStamp which holds usec instead of ms.
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//
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// Revision 1.9 1999/01/08 19:27:37 curt
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// Fixed AOA reading on HUD.
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// Continued work on time jitter compensation.
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//
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// Revision 1.8 1999/01/08 03:23:51 curt
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// Beginning work on compensating for sim time vs. real world time "jitter".
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//
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// Revision 1.7 1998/12/18 23:37:07 curt
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// Collapsed out the FGState variables not currently needed. They are just
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// commented out and can be readded easily at any time. The point of this
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// exersize is to determine which variables were or were not currently being
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// used.
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//
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// Revision 1.6 1998/12/05 15:54:11 curt
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// Renamed class fgFLIGHT to class FGState as per request by JSB.
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//
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// Revision 1.5 1998/12/04 01:29:39 curt
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// Stubbed in a new flight model called "External" which is expected to be driven
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// from some external source.
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//
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// Revision 1.4 1998/12/03 01:16:40 curt
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// Converted fgFLIGHT to a class.
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//
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// Revision 1.3 1998/11/06 21:18:03 curt
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// Converted to new logstream debugging facility. This allows release
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// builds with no messages at all (and no performance impact) by using
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// the -DFG_NDEBUGNDEBUG flag.
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//
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// Revision 1.2 1998/10/16 23:27:40 curt
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// C++-ifying.
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//
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// Revision 1.1 1998/10/16 20:16:41 curt
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// Renamed flight.[ch] to flight.[ch]xx
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//
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// Revision 1.19 1998/09/29 14:57:38 curt
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// c++-ified comments.
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//
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// Revision 1.18 1998/09/29 02:02:40 curt
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// Added a rate of climb calculation.
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//
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// Revision 1.17 1998/08/24 20:09:07 curt
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// .
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//
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// Revision 1.16 1998/08/22 14:49:55 curt
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// Attempting to iron out seg faults and crashes.
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// Did some shuffling to fix a initialization order problem between view
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// position, scenery elevation.
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//
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// Revision 1.15 1998/07/30 23:44:36 curt
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// Beginning to add support for multiple flight models.
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//
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// Revision 1.14 1998/07/12 03:08:27 curt
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// Added fgFlightModelSetAltitude() to force the altitude to something
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// other than the current altitude. LaRCsim doesn't let you do this by just
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// changing FG_Altitude.
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//
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// Revision 1.13 1998/04/25 22:06:28 curt
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// Edited cvs log messages in source files ... bad bad bad!
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//
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// Revision 1.12 1998/04/21 16:59:33 curt
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// Integrated autopilot.
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// Prepairing for C++ integration.
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//
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// Revision 1.11 1998/04/18 04:14:04 curt
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// Moved fg_debug.c to it's own library.
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//
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// Revision 1.10 1998/02/07 15:29:37 curt
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// Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
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// <chotchkiss@namg.us.anritsu.com>
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//
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// Revision 1.9 1998/01/27 00:47:53 curt
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// Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
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// system and commandline/config file processing code.
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//
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// Revision 1.8 1998/01/19 19:27:03 curt
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// Merged in make system changes from Bob Kuehne <rpk@sgi.com>
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// This should simplify things tremendously.
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//
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// Revision 1.7 1998/01/19 18:40:23 curt
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// Tons of little changes to clean up the code and to remove fatal errors
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// when building with the c++ compiler.
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//
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// Revision 1.6 1998/01/19 18:35:43 curt
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// Minor tweaks and fixes for cygwin32.
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//
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// Revision 1.5 1997/12/30 20:47:37 curt
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// Integrated new event manager with subsystem initializations.
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//
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// Revision 1.4 1997/12/10 22:37:42 curt
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// Prepended "fg" on the name of all global structures that didn't have it yet.
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// i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
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//
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// Revision 1.3 1997/08/27 03:30:04 curt
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// Changed naming scheme of basic shared structures.
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//
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// Revision 1.2 1997/05/29 22:39:57 curt
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// Working on incorporating the LaRCsim flight model.
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//
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// Revision 1.1 1997/05/29 02:35:04 curt
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// Initial revision.
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//
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