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ATL_ELEVATION(3T)      AVIATOR TERRAIN LIBRARY FUNCTIONS      ATL_ELEVATION(3T)



NAME
        atl_elevation - generate elevations in Aviator terrain data files

SYNOPSIS
        #include <atl.h>

        int atl_elevation(long_00, lat_00, long_0c, lat_0c,
                          long_r0, lat_r0, long_rc, lat_rc,
                          filename, num_rows, num_cols)
        double long_00, lat_00, long_0c, lat_0c;
        double long_00, lat_r0, long_rc, lat_rc;
        char   *filename;
        int    num_rows, num_cols;

DESCRIPTION
        atl_elevation() changes or creates the elevations in the data files
        used by Aviator.  The data files have filenames of ???_??? where ? is
        a number.

        filename points to the pathname of a file containing the elevations
        that are to be converted.  The file must contain the elevation data in
        the format of an array of integers:

                int elevation[num_rows][num_cols];

        The array, elevation[num_rows][num_cols], contains the heights
        measured in millimeters from sea level.

        long_00 and lat_00 represent the longitude and latitude of the
        location on the globe of the elevation[0][0].  long_0c and lat_0c
        indicate the location the elevation[0][num_cols-1].  long_r0 and
        lat_r0 indicate the location the elevation[num_rows-1][0].  long_rc
        and lat_rc indicate the location the elevation[num_rows-1][num_cols-1].
        All longitudes are measured in degrees from the Meridian of Greenwich
        and all latitudes are measured in degrees from the Equator.

        atl_elevation() allows the elevations of the data files to be handled
        in small sections.  When all the elevations have been generated,
        atl_elevation_post() must be run on all of the data.

RETURN VALUES
        atl_elevation() returns:
        0       on success.
        -1      on failure.

FILES
        /usr/games/aviator/atl/h/atl.h
        /usr/games/aviator/atl/lib/libatl.a
        /usr/games/aviator/passwords
        /usr/games/aviator/terrain/???_???

ENVIRONMENT
        The environment variable AVIATOR_HOME points to the home directory for
        aviator, if it is other than /usr/games/aviator.  AVIATOR_PASSWORDS
        points to the file that contains the password file passwords, if it is
        other than /usr/games/aviator/passwords or ${AVIATOR_HOME}/passwords.
        passwords contains the password needed to use atl_color().  The
        following are examples of how to set AVIATOR_HOME and
        AVIATOR_PASSWORDS:

                setenv AVIATOR_HOME      /home/bigdisk/aviator
                setenv AVIATOR_PASSWORDS /home/bigdisk/aviator/passwords

SEE ALSO
        atl_elevation_post(3T), passwords(5A)



ATL Release 1.8         Last change: 25 December 1991