Index Page dski02_c

A B C D E F G H I J K L M N O P Q R S T U V W X

Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       void dski02_c ( SpiceInt              handle,
                       ConstSpiceDLADescr  * dladsc,
                       SpiceInt              item,
                       SpiceInt              start,
                       SpiceInt              room,
                       SpiceInt            * n,
                       SpiceInt            * values   )

#### Abstract

       Fetch integer data from a type 2 DSK segment.

#### Required_Reading

       DAS
       DSK

#### Keywords

       DAS
       DSK
       FILES
       TOPOGRAPHY

#### Brief_I/O

       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       handle     I   DSK file handle.
       dladsc     I   DLA descriptor.
       item       I   Keyword identifying item to fetch.
       start      I   Start index.
       room       I   Amount of room in output array.
       n          O   Number of values returned.
       values     O   Array containing requested item.

#### Detailed_Input

       handle         is the handle of a DSK file containing a type 2
                      segment from which data are to be fetched.

       dladsc         is the DLA descriptor associated with the segment
                      from which data are to be fetched.

       item           is an integer "keyword" parameter designating the
                      integer data item to fetch.

                      Names, meanings, and value of keyword parameters
                      supported by this routine are given in the header
                      file

                         SpiceDSK.h

                      The keyword parameters for integer data listed there
                      are supported by this routine.

       start          is the start index within specified data item from
                      which data are to be fetched. The index of the first
                      element of each data item is 0. This convention
                      applies uniformly to all data, even if the data are
                      associated with a set of 1-based indices. For
                      example, the plate ID range starts at 1 (this fact is
                      language-independent), but a caller would use a
                      `start' value of 0 to fetch the vertex indices of the
                      first plate.

       room           is the amount of room in the output array. It is
                      permissible to provide an output array that has too
                      little room to fetch an item in one call.

#### Detailed_Output

       n              is the number of elements fetched to the output
                      array `values'. `n' is normally in the range
                      1:room; if an error occurs on the call, `n' is
                      undefined.

       values         is a contiguous set of elements of the item
                      designated by `item'. The correspondence of
                      `values' with the elements of the data item is:

                         values[0]      item[start]
                           ...             ...
                         values[n-1]    item[start+n-1]

                      If an error occurs on the call, `values' is
                      undefined.

#### Parameters

       See the header files

          SpiceDLA.h
          SpiceDSK.h

#### Exceptions

       1) If the input handle is invalid, the error will be diagnosed by
          routines in the call tree of this routine.

       2) If a file read error occurs, the error will be diagnosed by
          routines in the call tree of this routine.

       3) If the input DLA descriptor is invalid, the effect of this
          routine is undefined. The error *may* be diagnosed by routines
          in the call tree of this routine, but there are no
          guarantees.

       4) If `room' is non-positive, the error SPICE(VALUEOUTOFRANGE)
          is signaled.

       5) If the coarse voxel scale read from the designated segment
          is less than 1, the error PICE(VALUEOUTOFRANGE) is signaled.

       6) If the input keyword parameter is not recognized, the error
          SPICE(NOTSUPPORTED) is signaled.

       7) If `start' is less than 0 or greater than or equal to the size of
          the item to be fetched, the error SPICE(INDEXOUTOFRANGE) is
          signaled.

#### Files

       See input argument `handle'.

#### Particulars

       Most SPICE applications will not need to call this routine. The
       routines dskv02_c, dskp02_c, and dskz02_c provide a higher-level
       interface for fetching DSK type 2 vertex and plate data.

       DSK files are built using the DLA low-level format and
       the DAS architecture; DLA files are a specialized type of DAS
       file in which data are organized as a doubly linked list of
       segments.  Each segment's data belong to contiguous components of
       character, double precision, and integer type.

       Note that the DSK descriptor for the segment is not needed by this
       routine; the DLA descriptor contains the base address and size
       information for the integer, double precision, and character
       components of the segment, and these suffice for the purpose of
       fetching data.

#### Examples

       The numerical results shown for this example may differ across
       platforms. The results depend on the SPICE kernels used as
       input, the compiler and supporting libraries, and the machine
       specific arithmetic implementation.

       1) Look up all the vertices associated with each plate
          of the model contained in a specified type 2 segment.
          For this example, we'll show the context of this look-up:
          opening the DSK file for read access, traversing a trivial,
          one-segment list to obtain the segment of interest.

       Example code begins here.

             #include <stdio.h>
             #include "SpiceUsr.h"
             #include "SpiceDLA.h"
             #include "SpiceDSK.h"

             int main()
             {

                /.
                Local parameters
                ./
                #define FILSIZ          256

                /.
                Local variables
                ./
                SpiceBoolean            found;

                SpiceChar               dsk     [ FILSIZ ];

                SpiceDLADescr           dladsc;

                SpiceDouble             vrtces  [3][3];

                SpiceInt                handle;
                SpiceInt                i;
                SpiceInt                j;
                SpiceInt                n;
                SpiceInt                np;
                SpiceInt                start;
                SpiceInt                vrtids  [3];

                /.
                Prompt for the name of the DSK to read.
                ./
                prompt_c ( "Enter DSK name > ", FILSIZ, dsk );

                /.
                Open the DSK file for read access. We use the DAS-level
                interface for this function.
                ./
                dasopr_c ( dsk, &handle );

                /.
                Begin a forward search through the kernel, treating the
                file as a DLA. In this example, it's a very short search.
                ./
                dlabfs_c ( handle, &dladsc, &found );

                if ( !found  )
                {
                   /.
                   We arrive here only if the kernel
                   contains no segments.  This is
                   unexpected, but we're prepared for it.
                   ./
                   setmsg_c ( "No segments found in DSK file #." );
                   errch_c  ( "#", dsk                           );
                   sigerr_c ( "SPICE(NODATA)"                    );
                }

                /.
                If we made it this far, `dladsc' is the
                DLA descriptor of the first segment.

                Find the number of plates in the model.
                ./
                dski02_c ( handle, &dladsc, SPICE_DSK02_KWNP,
                           0,      1,       &n,             &np );

                /.
                For each plate, look up the desired data.
                ./
                for ( i = 1;  i <= np;  i++ )
                {
                   /.
                   For the Ith plate, find the associated
                   vertex IDs.  We must take into account
                   the fact that each plate has three
                   vertices when we compute the start
                   index.
                   ./
                   start = 3*(i-1);

                   dski02_c ( handle, &dladsc, SPICE_DSK02_KWPLAT, start,
                              3,      &n,      vrtids                   );

                   for ( j = 0;  j < 3;  j++  )
                   {
                      /.
                      Fetch the vertex associated with
                      the jth vertex ID.  Again, each
                      vertex is a 3-vector.  Note that
                      the vertices are double-precision
                      data, so we fetch them using
                      dskd02_c.
                      ./
                      start = (vrtids[j]-1)*3;

                      dskd02_c ( handle, &dladsc, SPICE_DSK02_KWVERT, start,
                                 3,      &n,      vrtces[j]               );
                   }

                   /.
                   Display the vertices of the ith plate:
                   ./
                   printf ( "\n"
                            "Plate number:  %d\n"
                            "   Vertex 1: ( %+e   %+e   %+e )\n"
                            "   Vertex 2: ( %+e   %+e   %+e )\n"
                            "   Vertex 3: ( %+e   %+e   %+e )\n",
                            (int)i,
                            vrtces[0][0], vrtces[0][1], vrtces[0][2],
                            vrtces[1][0], vrtces[1][1], vrtces[1][2],
                            vrtces[2][0], vrtces[2][1], vrtces[2][2]  );
                }

                /.
                Close the kernel.  This isn't necessary in a stand-
                alone program, but it's good practice in subroutines
                because it frees program and system resources.
                ./
                dascls_c ( handle );

                return ( 0 );
             }

       When this program was run on a PC/Linux/gcc/64-bit platform,
       using a DSK file containing data representing a regular
       icosahedron, the output was:

          Plate number:  1
             Vertex 1: ( +0.000000e+00   +0.000000e+00   +1.175570e+00 )
             Vertex 2: ( +1.051460e+00   +0.000000e+00   +5.257310e-01 )
             Vertex 3: ( +3.249200e-01   +1.000000e+00   +5.257310e-01 )

          Plate number:  2
             Vertex 1: ( +0.000000e+00   +0.000000e+00   +1.175570e+00 )
             Vertex 2: ( +3.249200e-01   +1.000000e+00   +5.257310e-01 )
             Vertex 3: ( -8.506510e-01   +6.180340e-01   +5.257310e-01 )

             ...

          Plate number:  20
             Vertex 1: ( +8.506510e-01   -6.180340e-01   -5.257310e-01 )
             Vertex 2: ( +0.000000e+00   +0.000000e+00   -1.175570e+00 )
             Vertex 3: ( +8.506510e-01   +6.180340e-01   -5.257310e-01 )

#### Restrictions

       1) The underlying f2c'd routine

             dski02_

          called by this routine uses discovery check-in to boost execution
          speed.  However, that routine is in violation of NAIF standards
          for use of discovery check-in:  routines called from that routine
          may signal errors.  If errors are signaled in routines called
          from dski02_, that routine's name will be missing from the
          traceback message.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman    (JPL)

#### Version

       -CSPICE Version 1.0.0, 04-APR-2017 (NJB)

          Updated parameter references in example program.
          Removed unnecessary include statements.
          Updated header.

          DSKLIB_C Version 1.0.1, 11-JUL-2014 (NJB)

             Corrected minor header comment typos.

          DSKLIB_C Version 1.0.0, 11-FEB-2010 (NJB)

#### Index_Entries

       fetch integer data from a type 2 dsk segment

#### Link to routine dski02_c source file dski02_c.c

    Wed Apr  5 17:54:32 2017