surface topology data converter

[Wookey]

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On Thu 30 Jan, Erin Lynch wrote:
> Sorry to bother everyone, but does anyone have a copy
> of the C program mentioned by Wookey in:
> 
> http://www.chaos.org.uk/survex/cp/CP11/CPoint11.htm#Art_5
> 
> I have surface topology in HPGL, and I'd like to
> convert it to a format survex can use.  Thanks.

Hmm, I've almost certainly got a copy somewhere, but it may take a while to
find.

This would probably be better done a perl or python script these days, but
that's still work for someone.


<fx: wanders round computer for a bit>

got it:
One naff bit of 1994 vintage c code attached.

Wookey
-- 
Aleph One Ltd, Bottisham, CAMBRIDGE, CB5 9BA, UK  Tel +44 (0) 1223 811679
work: http://www.aleph1.co.uk/     play: http://www.chaos.org.uk/~wookey/

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/* 1994.09.09  HPtoSVX.C */
/* HPGL to SVX contour converter */
/* Wookey */

/* This code is released under the GNU GPL */

/* takes lines in from HPGL file. If there is a PR line indicating relative
co-ords it stops */
/* For each PU (pen up=3Dmove) command it assumes a new traverse is startin=
g
and writes a new *begin command*/
/* for each PD (pen down=3Ddraw) command it just adds the corresponding leg
to the SVX file */

/* you should get a file in sections with each connected traverse having a
different name, fixed point, and section */

/* There are no heights, as they are not in the original data - you have to
work them out yourself and use search & replace to put them in */

#define INFILE "CONTOUR"
#define OUTFILE "CONTSVX"
#define BUFLEN 20
#define DEBUG 0
#define PI 3.14

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

extern int main (void)
{
 FILE *HPGL,*SVX;
 char command[3];
 int x=3D0,oldx=3D0,y=3D0,oldy=3D0,deltax,deltay;
 char buf[BUFLEN];
 int cpoint=3D0;
 char label[11]=3D"cont";
 int clabel=3D0;
 int numfields;
 double value, comp, tape;

 HPGL =3D fopen (INFILE, "rt");
 if (HPGL=3D=3DNULL)
  {
  printf ("couldn't open input HPGL file\n");
  exit(0);
  }
 SVX =3D fopen (OUTFILE, "w");
 if (SVX=3D=3DNULL)
  {
  printf ("couldn't open output .SVX file\n");
  exit(0);
  }

 while (fgets(buf, BUFLEN, HPGL)!=3DNULL)
  {
  #if DEBUG
  printf ("%s\n", buf);
  #endif
  numfields =3D sscanf (buf, "%2s %d,%d", command,&x,&y);
  #if DEBUG
  printf ("%s %d %d\n", command, x, y);
  #endif
  switch (numfields)
   {
    case (0):
     {
     printf ("empty line\n");
     break;
     }
    case (1):
     {
     if (strcmp(command, "PA")=3D=3D0)
      printf ("Absolute Coordinates\n");
     else
      if (strcmp(command, "PR")=3D=3D0)
       {
       printf ("Relative co-ordinates not implemented - aborting\n");
       exit(0);
       }
      printf ("command ignored\n");
     break;
     }
    case (2):
     {
     printf ("invalid line\n");
     break;
     }
    case (3):
     {
     if (strcmp(command,"PU")=3D=3D0) /* start new traverse */
      {
      if (clabel!=3D0)
      /* fprintf(SVX,"*END %s%d\n\n",label,clabel);*/ /* don't do it 1st ti=
me */
      printf ("converting traverse %s%d\n",label,clabel);
      clabel=3Dclabel+100;
      cpoint=3D0;
      fprintf(SVX,"*PREFIX \\%s%d\n",label,clabel);
      /*fprintf(SVX,"*BEGIN %s%d\n",label,clabel);
*/
      fprintf(SVX,"*FIX %d %d %d %d\n",cpoint, x, y, clabel);
      oldx=3Dx;oldy=3Dy; /* reset 'from' co-ords */
      }

     if (strcmp(command,"PD")=3D=3D0)
      {
      deltax=3Doldx-x;
      deltay=3Doldy-y;
     /* if (deltay=3D=3D0) /* straight north or south - avoid fp exception =
*/
       /*{
       if (deltax>=3D0) comp=3D0.0;
       if (deltax<0) comp=3D180;
       }
      else */
       {
       value=3Datan2((double)deltax,(double)deltay);
       comp=3D(360.0*value)/(2.0*PI)+180;
       }

      tape=3Dsqrt(((double)deltax*(double)deltax) + ((double)deltay*(double=
)deltay));
      fprintf(SVX,"%d %d %d %d 0\n",cpoint, cpoint+1, (int)tape, (int)comp)=
;
      cpoint++;
      oldx=3Dx;oldy=3Dy; /* reset 'from' co-ords */
       }
     }
   }
  };  /*do*/
  /*fprintf (SVX,"*END %s%d\n",label,clabel);*/ /* complete last survey blo=
ck */
 /* tidy up */
 fclose (HPGL);
 fclose (SVX);

}

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