void dskp02_c ( SpiceInt handle,
ConstSpiceDLADescr * dladsc,
SpiceInt start,
SpiceInt room,
SpiceInt * n,
SpiceInt plates[][3] )
Fetch triangular plates from a type 2 DSK segment.
DAS
DSK
DAS
DSK
FILES
Variable 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 plates returned.
plates O Array containing plates.
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 plate to be fetched from the
segment designated by `handle' and `dladsc'. The ID
of a plate is its ordinal position within the
segment. Plate IDs range from 1 to NP, where NP is
the number of plates in the segment.
Note that Fortran-style 1-based indexing is used for
plate 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 plates that can fit in the output
`plates' array: the output array must be large enough
to hold at least 3*room integer values.
n is the number of plates fetched to the output
array `plates'. `n' is normally in the range
1 : min( NP, room )
If an error occurs on the call, `n' is undefined.
plates is a contiguous set of plates. The returned
plates are arranged in order of increasing plate
ID. The IDs of the returned plates range from
start
to
start + n - 1
Each plate consists of three vertex indices. The
correspondence of elements of `plates' with the
elements of the set of plates contained in the
segment is:
plates[0][0] plate_set[start][0]
plates[0][1] plate_set[start][1]
plates[0][2] plate_set[start][2]
... ...
plates[n-1][0] plate_set[start+n-1][0]
plates[n-1][1] plate_set[start+n-1][1]
plates[n-1][2] plate_set[start+n-1][2]
If an error occurs on the call, `plates' is
undefined.
See the header file
SpiceDLA.h
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 `start' is less than 1 or greater than the number of plates
in the segment, the error SPICE(INDEXOUTOFRANGE) is signaled.
See input argument `handle'.
This routine enables SPICE-based user applications to rapidly
fetch the plate data from a specified type 2 DSK segment. Using
a large output array generally improves efficiency.
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
plate, 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.
#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 plate.
./
remain = 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 PC/Linux/gcc/64bit
platform, using a DSK file representing a regular icosahedron,
the output was:
Number of vertices: 12
Number of plates: 20
Plate number: 1
Vertex 1: ( 0.00000000e+00 0.00000000e+00 1.17557000e+00 )
Vertex 2: ( 1.05146000e+00 0.00000000e+00 5.25731000e-01 )
Vertex 3: ( 3.24920000e-01 1.00000000e+00 5.25731000e-01 )
Normal: ( 4.91124160e-01 3.56821347e-01 7.94654382e-01 )
Plate number: 2
Vertex 1: ( 0.00000000e+00 0.00000000e+00 1.17557000e+00 )
Vertex 2: ( 3.24920000e-01 1.00000000e+00 5.25731000e-01 )
Vertex 3: ( -8.50651000e-01 6.18034000e-01 5.25731000e-01 )
Normal: ( -1.87592328e-01 5.77350079e-01 7.94654645e-01 )
...
Plate number: 20
Vertex 1: ( 8.50651000e-01 -6.18034000e-01 -5.25731000e-01 )
Vertex 2: ( 0.00000000e+00 0.00000000e+00 -1.17557000e+00 )
Vertex 3: ( 8.50651000e-01 6.18034000e-01 -5.25731000e-01 )
Normal: ( 6.07061680e-01 0.00000000e+00 -7.94654715e-01 )
None.
None.
N.J. Bachman (JPL)
-CSPICE Version 1.1.0, APR-04-2017 (NJB)
Removed references to old header files. Updated
example program.
-DSKLIB_C Version 1.0.1, 22-APR-2014 (NJB)
The diagram in the Detailed_Output header section showing the
contents of the output `plates' array has been corrected.
-DSKLIB_C Version 1.0.0, 04-JUN-2010 (NJB)
fetch plate data from a type 2 dsk segment
Link to routine dskp02_c source file dskp02_c.c
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