get_topo_coord.c

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#include "prototypes.h"
 
void get_topo_coord(char *fname)
 
{
 
 int i,j,ier,maxj,maxi,max_value,k;
 float lat,lon;
 extern struct topo *topo;
 FILE *fp;
 char *p,kbuf[10000];
 float max_lat,max_lon,delta_lat,delta_lon,total_lat,total_lon;
 
 topo=(struct topo *) calloc(1,sizeof(struct topo));
 if(topo==NULL) {
 
                   printf("could not allocate topo space\n");
                   exit(1);
 
                  }          
 
 max_value=0;
 
 fp=fopen(fname,"r");
 
 if(fp==NULL) {
 
              printf("could not open %s\n",fname);
              exit(1);
 
              }
 
 p=fgets(kbuf,80,fp);
 
 ier=sscanf(kbuf,"%f %f %f %f %f %f",&max_lat,&max_lon,&total_lat,&total_lon,&delta_lat,&delta_lon);
 delta_lat=delta_lat/60.;
 delta_lon=delta_lon/60.;
 
 maxi=total_lon/delta_lon+1;
 maxj=total_lat/delta_lat+1;
 
 topo->maxi=maxi;
 topo->maxj=maxj;
 topo->max_lat=max_lat;
 topo->max_lon=max_lon;
 topo->total_lat=total_lat;
 topo->total_lon=total_lon;
 topo->delta_lat=delta_lat;
 topo->delta_lon=delta_lon;
 
 topo->coord=(struct coord**) calloc(maxi,sizeof(struct coord *));
 topo->value=(short int**) calloc(maxi,sizeof(short int *));
 
 if(topo->coord==NULL || topo->value==NULL) {
 
                            printf("no memory for topo array\n");
                            exit(1);
 
              }
 
 for(i=0;i<maxi;i++) {
 
      topo->coord[i]=(struct coord *) calloc(maxj,sizeof(struct coord));
 
      topo->value[i]=(short int *) calloc(maxj,sizeof(short int));
 
      if(topo->coord[i]==NULL || topo->value[i]==NULL) {
 
                printf("no memory for topo array\n");
                exit(1);
 
          }
 
    }
 
 for(j=0;j<maxj;j++) {
 
 fread(kbuf,sizeof(char),maxi*4,fp);
 
 k=0;
 
 for(i=0;i<maxi;i++) {
         
         topo->value[i][j]=atoi(&kbuf[k]);
 
         lat=max_lat-(float)j*delta_lat;
         lon=max_lon-(float)i*delta_lon;
 
         get_topo_pixels(i,j,lat,lon);
 
         k=k+4;         
 
    }
 
   }
 
fclose(fp);
 
return;
 
}
void get_topo_pixels(int i, int j, float lat,float lon)
 
  {
 
     extern struct dval dval;
     long r,s;
     float conv=.0174;
     extern struct topo *topo;
     
     r=dval.a * cos(lat*conv)/(1+sin(lat*conv))
       * cos((lon-dval.lo-90)*conv) + dval.xo +.5;
 
     topo->coord[i][j].x=r;
 
     s=dval.a * cos(lat*conv)/(1+sin(lat*conv))
       * sin((lon-dval.lo-90)*conv) + dval.yo + .5;
       
     topo->coord[i][j].y=s;
 
     return;
 
   }