vos/metaobjects/property/gps_position.hh

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/* $Id: gps_position.hh,v 1.16 2003/07/24 23:08:35 reed Exp $ */

/*  Copyright (C) 2001, 2002 Reed Hedges <reed@zerohour.net>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA

*/

#ifndef _GPS_POSITION_H_
#define _GPS_POSITION_H_

#include <stdio.h>
#include <vos/corelibs/vos/vos.hh>
#include <vos/metaobjects/property/property.hh>

/* This specialization of LocalProperty is meant to get its data from gpsd, the Global
    Positioning System daemon by Remco Treffkorn: <http://russnelson.com/gpsd/>.

    @deprecated libtracking now provides an interface to GPSD, so you should
        use that, perhaps running a little background process to update a 
        property. Sorry, but this class isn't being used by anyone (as far
        as we know) at the 
        moment and it's a bit esoteric to be a standard member of the property
        classes.

    gpsd listens on a TCP port and responds to simple commands with data from a GPS
    hooked up to the computer by serial cable. (I have noted most of the commands
    in the source, gps_position.cc).  The latutude (LAT), longitude (LON) and altitutde
    (ALT) of the GPS are stored in the property in this format (the format conforms to 
    that of a3dl object3d position property, with "room" as an arbitrary sector name):

        "LAT ALT LON room"
    
    That is, latitutde is interpreted as X, longitude as Z, and altitude as Y.

    If we decide to split up 3D object position, this class might be modified to
    represent only one component (X, Y, or Z) rather than have all three together 
    as object3d currently does. I think the default will be to have all three, though,
    to remain backwards compatible.


    @author Reed Hedges <reed@zerohour.net> 2/25/02

*/

/** The default gpsd 1.06 TCP port. */
#define GPSD_DEFAULT_PORT 2947

/** Default position precision for values in printf() format string */
#define GPSPROP_DEFAULT_PRECISION 15

/** Default threshold before new property is set (and update messages sent). */
#define GPSPROP_DEFAULT_THRESHOLD 0

class GPSPosition : public LocalProperty {

public:

    /** An exception that indicates a general error communicating to server through network socket. (use ServerCommError::what() to get a descriptive string) */
    class ServerCommError : public runtime_error {
    public:
        ServerCommError(const string& s) : runtime_error(s) {}
    };

protected:

    int socket_fd;
    static char* gpsd_host;
    static int gpsd_port;

    /* scale factors (multipliers) */
    double lat_scale;
    double lon_scale;
    double alt_scale;

    /* offsets */
    double lat_off;
    double lon_off;
    double alt_off;

    /* fixed altitude? */
    bool fix_alt;
    double fixed_alt_val;

    /* Store values from last update */
    double last_lat;
    double last_lon;
    double last_alt;

    /* Threshold difference from last value before the new values are written (and
     * update messages are sent). Use setThreshold to change. */
    double threshold;

    /* Format string for creating position property. Use setPrecision to change. */
    char position_format[64];

    
public:

    /** Constructor: initializes values and oens socket to gpsd */
    GPSPosition(MetaObject *super) throw (ServerCommError);

    /** Destructor: closes socket. */
    ~GPSPosition(); 

    /** Register GPSPosition with MetaFactory by typeid(GPSPosition).name, as a local object extension. You must also call Property::registerExtenders()! */
    static void registerExtenders() {
        LocalSite::addLocalObjectExtension(typeid(GPSPosition).name(), &GPSPosition::new_GPSPosition);
    }

    /** This method is used by MetaFactory to create a new instance of this class. */
    static MetaObject* new_GPSPosition(MetaObject* super, const string& type) {
        return new GPSPosition(super);
    }

    /** Set precision of values.  The default value is 15 decimal places.  Must
     * be an integer value >= 0 and <= 15. 
     * @precision new precision value
     * @throws range_error if requested precision value is > 15 or < 0.*/
    void setPrecision(int precision) throw (range_error);

    /** Set threshold of change before property value is replaced on update()
     * (and therefore update messages sent to listeners) */
    void setThreshold(double t) {
        threshold = t;
    }

    /** Update value from gpsd after which you can use read() to get the new value. Call at intervals, or right before a read. Only changes the property value (with a call to replace()) if the difference from the last update is greater than the threshold.
     * @see setThreshold()
     * @see setPrecision()
     */
    void update() throw (ServerCommError);

    /** Send status command to gpsd and return response. -1 is returned on connection/communicaiton error. */
    int getStatus() throw(ServerCommError);

    /** Set default gpsd server for future GPSPosition objects 
        @param host Numerical host address. Default is "127.0.0.1" 
        @param port Port number. Default is GPSD_DEFAULT_PORT (2947). */
    static void setServer(char* host = "127.0.0.1", int port = GPSD_DEFAULT_PORT) {
        gpsd_host = host;
        gpsd_port = port;
    }

    /** Set scaling multipliers.  ( (Final value) = (Original value + Offset) * Scaling ). */
    void setScaling(double latitude, double longitude, double altitude);

    /** Set offsets. ( (Final value) = (Original value + Offset) * Scaling ). */
    void setOffsets(double latitude, double longitude, double altitude);

    /** Fix altitude (Y position) to some value. */
    void fixAltitude(double val) {
        fix_alt = true;
        fixed_alt_val = val;
    }
};





#endif

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