| dskv02_c |
|
Table of contents
Procedure
dskv02_c ( DSK, fetch type 2 vertex data )
void dskv02_c ( SpiceInt handle,
ConstSpiceDLADescr * dladsc,
SpiceInt start,
SpiceInt room,
SpiceInt * n,
SpiceDouble vrtces[][3] )
AbstractFetch vertices from a type 2 DSK segment. Required_ReadingDAS DSK KeywordsDAS DSK FILES Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- handle I DSK file handle. dladsc I DLA descriptor. start I Start index. room I Amount of room in output array. n O Number of vertices returned. vrtces O Array containing vertices. 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.
start is the ID of the first vertex to be fetched from
the segment designated by `handle' and `dladsc'. The
ID of a vertex is its ordinal position within the
segment. Vertex IDs range from 1 to `nv', where `nv'
is the number of vertices in the segment.
Note that Fortran-style 1-based indexing is used for
vertex IDs because these IDs must be consistent with
the IDs used in DSK files, across all languages
supported by SPICE.
room is the number of vertices that can fit in the output
`vrtces' array: the output array must be large enough
to hold at least 3*room double precision values.
Detailed_Output
n is the number of vertices fetched to the output
array `vrtces'. `n' is normally in the range
1 : min( nv, room )
If an error occurs on the call, `n' is undefined.
vrtces is a contiguous set of vertices. The returned
vertices are arranged in order of increasing vertex
ID. The IDs of the returned vertices range from
start
to
start + n - 1
Each vertex is a 3-vector. The correspondence of
elements of `vrtces' with the elements of the set of
vertices contained in the segment is:
vrtces[0][0] segment_vertex_set[start][0]
vrtces[0][1] segment_vertex_set[start][1]
vrtces[0][2] segment_vertex_set[start][2]
... ...
vrtces[n-1][0] segment_vertex_set[start+n-1][0]
vrtces[n-1][1] segment_vertex_set[start+n-1][1]
vrtces[n-1][2] segment_vertex_set[start+n-1][2]
The vertices are expressed in the body-fixed
reference frame of the segment designated by
`handle' and `dladsc'. The center of this frame is the
origin of the Cartesian coordinate system in which
the vertices are expressed. Note that the frame
center need not coincide with the central body of
the segment. Units are km.
If an error occurs on the call, `vrtces' is
undefined.
Parameters
See the header file
SpiceDLA.h
for declarations of DLA descriptor sizes and documentation of the
contents of DLA descriptors.
See the header file
SpiceDSK.h
for declarations of DSK descriptor sizes and documentation of the
contents of DSK descriptors.
See the header file
SpiceDSK.h
for declarations of DSK data type 2 (plate model) parameters.
Exceptions
1) If the input handle is invalid, an error is signaled by a
routine in the call tree of this routine.
2) If a file read error occurs, the error is signaled by a
routine 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 by a routine in the call tree of this routine.
5) If `start' is less than 1 or greater than the number of
vertices in the segment, the error SPICE(INDEXOUTOFRANGE) is
signaled by a routine in the call tree of this routine.
FilesSee input argument `handle'. ParticularsThis routine enables SPICE-based user applications to rapidly fetch the vertex data from a specified type 2 DSK segment. Using a large output array generally improves efficiency. 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 each
of the first 5 plates, display the plate's vertices and normal
vector.
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.
/.
Program dskv02_ex1
./
#include <stdio.h>
#include "SpiceUsr.h"
int main()
{
/.
Constants
./
#define PBUFSIZ 10000
#define FILSIZ 256
/.
Local variables
./
SpiceBoolean found;
SpiceChar dsk [ FILSIZ ];
SpiceDLADescr dladsc;
SpiceDouble normal [3];
SpiceDouble verts [3][3];
SpiceInt handle;
SpiceInt i;
SpiceInt j;
SpiceInt n;
SpiceInt np;
SpiceInt nread;
SpiceInt nv;
SpiceInt nvtx;
SpiceInt plates[PBUFSIZ][3];
SpiceInt plix;
SpiceInt remain;
SpiceInt start;
/.
Prompt for name of DSK and open file for reading.
./
prompt_c ( "Enter DSK name > ", FILSIZ, dsk );
dasopr_c ( dsk, &handle );
dlabfs_c ( handle, &dladsc, &found );
if ( !found )
{
setmsg_c ( "No segment found in file #." );
errch_c ( "#", dsk );
sigerr_c ( "SPICE(NOSEGMENT)" );
}
/.
Get segment vertex and plate counts.
./
dskz02_c ( handle, &dladsc, &nv, &np );
printf ( "\n"
"Number of vertices: %d\n"
"Number of plates: %d\n",
(int)nv,
(int)np );
/.
Display the vertices of each of the first 5 plates.
./
remain = mini_c ( 2, 5, np );
start = 1;
while ( remain > 0 )
{
/.
`nread' is the number of plates we"ll read on this
loop pass.
./
nread = mini_c ( 2, PBUFSIZ, remain );
dskp02_c ( handle, &dladsc, start, nread, &n, plates );
for ( i = 0; i < nread; i++ )
{
plix = start + i;
/.
Read the vertices of the current plate.
./
for ( j = 0; j < 3; j++ )
{
dskv02_c ( handle, &dladsc, plates[i][j],
1, &nvtx,
( SpiceDouble(*)[3] )(verts[j]) );
}
/.
Display the vertices of the current plate:
./
printf ( "\n"
" Plate number: %d\n"
" Vertex 1: ( %16.8e %16.8e %16.8e )\n"
" Vertex 2: ( %16.8e %16.8e %16.8e )\n"
" Vertex 3: ( %16.8e %16.8e %16.8e )\n",
(int)plix,
verts[0][0], verts[0][1], verts[0][2],
verts[1][0], verts[1][1], verts[1][2],
verts[2][0], verts[2][1], verts[2][2] );
/.
Display the normal vector of the current plate:
./
dskn02_c ( handle, &dladsc, plix, normal );
printf( " Normal: ( %16.8e %16.8e %16.8e )\n",
normal[0], normal[1], normal[2] );
}
start = start + nread;
remain = remain - nread;
}
/.
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 executed on a Mac/Intel/cc/64-bit
platform, using the DSK file named phobos512.bds, the output
was:
Enter DSK name > phobos512.bds
Number of vertices: 1579014
Number of plates: 3145728
Plate number: 1
Vertex 1: ( -6.77444000e+00 6.26815000e+00 6.01149000e+00 )
Vertex 2: ( -6.76238000e+00 6.25728000e+00 6.02556000e+00 )
Vertex 3: ( -6.75710000e+00 6.27754000e+00 6.02096000e+00 )
Normal: ( -5.81973770e-01 3.21285613e-01 7.47048918e-01 )
Plate number: 2
Vertex 1: ( -6.77444000e+00 6.26815000e+00 6.01149000e+00 )
Vertex 2: ( -6.77973000e+00 6.24790000e+00 6.01610000e+00 )
Vertex 3: ( -6.76238000e+00 6.25728000e+00 6.02556000e+00 )
Normal: ( -5.81456950e-01 3.21988310e-01 7.47148809e-01 )
Plate number: 3
Vertex 1: ( -6.77973000e+00 6.24790000e+00 6.01610000e+00 )
Vertex 2: ( -6.76768000e+00 6.23701000e+00 6.03019000e+00 )
Vertex 3: ( -6.76238000e+00 6.25728000e+00 6.02556000e+00 )
Normal: ( -5.81597068e-01 3.22641957e-01 7.46757671e-01 )
Plate number: 4
Vertex 1: ( -6.77973000e+00 6.24790000e+00 6.01610000e+00 )
Vertex 2: ( -6.78499000e+00 6.22762000e+00 6.02070000e+00 )
Vertex 3: ( -6.76768000e+00 6.23701000e+00 6.03019000e+00 )
Normal: ( -5.83129010e-01 3.20560704e-01 7.46459237e-01 )
Plate number: 5
Vertex 1: ( -6.78499000e+00 6.22762000e+00 6.02070000e+00 )
Vertex 2: ( -6.77299000e+00 6.21674000e+00 6.03482000e+00 )
Vertex 3: ( -6.76768000e+00 6.23701000e+00 6.03019000e+00 )
Normal: ( -5.83664048e-01 3.23060196e-01 7.44962005e-01 )
RestrictionsNone. Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) Version
-CSPICE Version 1.0.1, 10-AUG-2021 (JDR)
Edited the header to comply with NAIF standard. Updated
code example to reduce the number of plates whose vertices are
shown on output.
Fixed -Exceptions entry #5: `start' ranges from 1 to the number
of vertices in the segment.
-CSPICE Version 1.0.0, 04-APR-2017 (NJB)
Updated header to refer to "vertex IDs."
27-JAN-2016 (NJB)
Removed references to old header files. Updated
example program. Updated -Detailed_Output header
section.
DSKLIB_C Version 1.0.1, 21-APR-2014 (NJB)
The diagram in the -Detailed_Output header section showing the
contents of the output `vrtces' array has been corrected.
DSKLIB_C Version 1.0.0 04-JUN-2010 (NJB)
Index_Entriesreturn specified vertices from type 2 DSK segment |
Fri Dec 31 18:41:05 2021