git.maemo.org Git - navit-package/blob - navit/transform.c

   1 /**
   2  * Navit, a modular navigation system.
   3  * Copyright (C) 2005-2008 Navit Team
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * version 2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the
  16  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301, USA.
  18  */
  19
  20 #include <assert.h>
  21 #include <stdio.h>
  22 #include <math.h>
  23 #include <limits.h>
  24 #include <glib.h>
  25 #include <string.h>
  26 #include "config.h"
  27 #include "coord.h"
  28 #include "debug.h"
  29 #include "map.h"
  30 #include "transform.h"
  31 #include "projection.h"
  32 #include "point.h"
  33 #include "item.h"
  34
  35 struct transformation {
  36         long scale;             /* Scale factor */
  37         int angle;              /* Rotation angle */
  38         double cos_val,sin_val; /* cos and sin of rotation angle */
  39         enum projection pro;
  40         struct map_selection *map_sel;
  41         struct map_selection *screen_sel;
  42         struct point screen_center;
  43         struct coord map_center;        /* Center of source rectangle */
  44 };
  45
  46 struct transformation *
  47 transform_new(void)
  48 {
  49         struct transformation *this_;
  50
  51         this_=g_new0(struct transformation, 1);
  52
  53         return this_;
  54 }
  55
  56 static const double gar2geo_units = 360.0/(1<<24);
  57 static const double geo2gar_units = 1/(360.0/(1<<24));
  58
  59 void
  60 transform_to_geo(enum projection pro, struct coord *c, struct coord_geo *g)
  61 {
  62         switch (pro) {
  63         case projection_mg:
  64                 g->lng=c->x/6371000.0/M_PI*180;
  65                 g->lat=atan(exp(c->y/6371000.0))/M_PI*360-90;
  66                 break;
  67         case projection_garmin:
  68                 g->lng=c->x*gar2geo_units;
  69                 g->lat=c->y*gar2geo_units;
  70                 break;
  71         default:
  72                 break;
  73         }
  74 }
  75
  76 void
  77 transform_from_geo(enum projection pro, struct coord_geo *g, struct coord *c)
  78 {
  79         switch (pro) {
  80         case projection_mg:
  81                 c->x=g->lng*6371000.0*M_PI/180;
  82                 c->y=log(tan(M_PI_4+g->lat*M_PI/360))*6371000.0;
  83                 break;
  84         case projection_garmin:
  85                 c->x=g->lng*geo2gar_units;
  86                 c->y=g->lat*geo2gar_units;
  87                 break;
  88         default:
  89                 break;
  90         }
  91 }
  92
  93 void
  94 transform_from_to(struct coord *cfrom, enum projection from, struct coord *cto, enum projection to)
  95 {
  96         struct coord_geo g;
  97         transform_to_geo(from, cfrom, &g);
  98         transform_from_geo(to, &g, cto);
  99 }
 100
 101 void
 102 transform_geo_to_cart(struct coord_geo *geo, double a, double b, struct coord_geo_cart *cart)
 103 {
 104         double n,ee=1-b*b/(a*a);
 105         n = a/sqrt(1-ee*sin(geo->lat)*sin(geo->lat));
 106         cart->x=n*cos(geo->lat)*cos(geo->lng);
 107         cart->y=n*cos(geo->lat)*sin(geo->lng);
 108         cart->z=n*(1-ee)*sin(geo->lat);
 109 }
 110
 111 void
 112 transform_cart_to_geo(struct coord_geo_cart *cart, double a, double b, struct coord_geo *geo)
 113 {
 114         double lat,lati,n,ee=1-b*b/(a*a), lng = atan(cart->y/cart->x);
 115
 116         lat = atan(cart->z / sqrt((cart->x * cart->x) + (cart->y * cart->y)));
 117         do
 118         {
 119                 lati = lat;
 120
 121                 n = a / sqrt(1-ee*sin(lat)*sin(lat));
 122                 lat = atan((cart->z + ee * n * sin(lat)) / sqrt(cart->x * cart->x + cart->y * cart->y));
 123         }
 124         while (fabs(lat - lati) >= 0.000000000000001);
 125
 126         geo->lng=lng/M_PI*180;
 127         geo->lat=lat/M_PI*180;
 128 }
 129
 130
 131 void
 132 transform_datum(struct coord_geo *from, enum map_datum from_datum, struct coord_geo *to, enum map_datum to_datum)
 133 {
 134 }
 135
 136 int
 137 transform(struct transformation *t, enum projection pro, struct coord *c, struct point *p, int count, int unique)
 138 {
 139         struct coord c1;
 140         int xcn, ycn;
 141         struct coord_geo g;
 142 #ifdef AVOID_FLOAT
 143         int xc,yc;
 144 #else
 145         double xc,yc;
 146 #endif
 147         int i,j = 0;
 148         for (i=0; i < count; i++) {
 149                 if (pro == t->pro) {
 150                         xc=c[i].x;
 151                         yc=c[i].y;
 152                 } else {
 153                         transform_to_geo(pro, &c[i], &g);
 154                         transform_from_geo(t->pro, &g, &c1);
 155                         xc=c1.x;
 156                         yc=c1.y;
 157                 }
 158 //              dbg(2,"0x%x, 0x%x - 0x%x,0x%x contains 0x%x,0x%x\n", t->r.lu.x, t->r.lu.y, t->r.rl.x, t->r.rl.y, c->x, c->y);
 159 //              ret=coord_rect_contains(&t->r, c);
 160                 xc-=t->map_center.x;
 161                 yc-=t->map_center.y;
 162                 yc=-yc;
 163                 if (t->angle) {
 164                         xcn=xc*t->cos_val+yc*t->sin_val;
 165                         ycn=-xc*t->sin_val+yc*t->cos_val;
 166                         xc=xcn;
 167                         yc=ycn;
 168                 }
 169                 xc=xc*16;
 170                 yc=yc*16;
 171 #ifndef AVOID_FLOAT
 172                 if (t->scale!=1) {
 173                         xc=xc/(double)(t->scale);
 174                         yc=yc/(double)(t->scale);
 175                 }
 176 #else
 177                 if (t->scale!=1) {
 178                         xc=xc/t->scale;
 179                         yc=yc/t->scale;
 180                 }
 181 #endif
 182                 xc+=t->screen_center.x;
 183                 yc+=t->screen_center.y;
 184                 if (xc < -0x8000)
 185                         xc=-0x8000;
 186                 if (xc > 0x7fff) {
 187                         xc=0x7fff;
 188                 }
 189                 if (yc < -0x8000)
 190                         yc=-0x8000;
 191                 if (yc > 0x7fff)
 192                         yc=0x7fff;
 193                 if (j == 0 || !unique || p[j-1].x != xc || p[j-1].y != yc) {
 194                         p[j].x=xc;
 195                         p[j].y=yc;
 196                         j++;
 197                 }
 198         }
 199         return j;
 200 }
 201
 202 void
 203 transform_reverse(struct transformation *t, struct point *p, struct coord *c)
 204 {
 205         int xc,yc;
 206         xc=p->x;
 207         yc=p->y;
 208         xc-=t->screen_center.x;
 209         yc-=t->screen_center.y;
 210         xc=xc*t->scale/16;
 211         yc=-yc*t->scale/16;
 212         if (t->angle) {
 213                 int xcn, ycn;
 214                 xcn=xc*t->cos_val+yc*t->sin_val;
 215                 ycn=-xc*t->sin_val+yc*t->cos_val;
 216                 xc=xcn;
 217                 yc=ycn;
 218         }
 219         c->x=t->map_center.x+xc;
 220         c->y=t->map_center.y+yc;
 221 }
 222
 223 enum projection
 224 transform_get_projection(struct transformation *this_)
 225 {
 226         return this_->pro;
 227 }
 228
 229 void
 230 transform_set_projection(struct transformation *this_, enum projection pro)
 231 {
 232         this_->pro=pro;
 233 }
 234
 235 static int
 236 min4(int v1,int v2, int v3, int v4)
 237 {
 238         int res=v1;
 239         if (v2 < res)
 240                 res=v2;
 241         if (v3 < res)
 242                 res=v3;
 243         if (v4 < res)
 244                 res=v4;
 245         return res;
 246 }
 247
 248 static int
 249 max4(int v1,int v2, int v3, int v4)
 250 {
 251         int res=v1;
 252         if (v2 > res)
 253                 res=v2;
 254         if (v3 > res)
 255                 res=v3;
 256         if (v4 > res)
 257                 res=v4;
 258         return res;
 259 }
 260
 261 struct map_selection *
 262 transform_get_selection(struct transformation *this_, enum projection pro, int order)
 263 {
 264
 265         struct map_selection *ret,*curri,*curro;
 266         struct coord_geo g;
 267         int i;
 268
 269         ret=map_selection_dup(this_->map_sel);
 270         curri=this_->map_sel;
 271         curro=ret;
 272         while (curri) {
 273                 if (this_->pro != pro) {
 274                         transform_to_geo(this_->pro, &curri->u.c_rect.lu, &g);
 275                         transform_from_geo(pro, &g, &curro->u.c_rect.lu);
 276                         dbg(1,"%f,%f", g.lat, g.lng);
 277                         transform_to_geo(this_->pro, &curri->u.c_rect.rl, &g);
 278                         transform_from_geo(pro, &g, &curro->u.c_rect.rl);
 279                         dbg(1,": - %f,%f\n", g.lat, g.lng);
 280                 }
 281                 dbg(1,"transform rect for %d is %d,%d - %d,%d\n", pro, curro->u.c_rect.lu.x, curro->u.c_rect.lu.y, curro->u.c_rect.rl.x, curro->u.c_rect.rl.y);
 282                 for (i = 0 ; i < layer_end ; i++)
 283                         curro->order[i]+=order;
 284                 curri=curri->next;
 285                 curro=curro->next;
 286         }
 287         return ret;
 288 }
 289
 290 struct coord *
 291 transform_center(struct transformation *this_)
 292 {
 293         return &this_->map_center;
 294 }
 295
 296 void
 297 transform_set_angle(struct transformation *t,int angle)
 298 {
 299         t->angle=angle;
 300         t->cos_val=cos(M_PI*t->angle/180);
 301         t->sin_val=sin(M_PI*t->angle/180);
 302 }
 303
 304 int
 305 transform_get_angle(struct transformation *this_,int angle)
 306 {
 307         return this_->angle;
 308 }
 309
 310 void
 311 transform_set_screen_selection(struct transformation *t, struct map_selection *sel)
 312 {
 313         map_selection_destroy(t->screen_sel);
 314         t->screen_sel=map_selection_dup(sel);
 315         if (sel) {
 316                 t->screen_center.x=(sel->u.p_rect.rl.x-sel->u.p_rect.lu.x)/2;
 317                 t->screen_center.y=(sel->u.p_rect.rl.y-sel->u.p_rect.lu.y)/2;
 318         }
 319 }
 320
 321 #if 0
 322 void
 323 transform_set_size(struct transformation *t, int width, int height)
 324 {
 325         t->width=width;
 326         t->height=height;
 327 }
 328 #endif
 329
 330 void
 331 transform_get_size(struct transformation *t, int *width, int *height)
 332 {
 333         struct point_rect *r;
 334         if (t->screen_sel) {
 335                 r=&t->screen_sel->u.p_rect;
 336                 *width=r->rl.x-r->lu.x;
 337                 *height=r->rl.y-r->lu.y;
 338         }
 339 }
 340
 341 void
 342 transform_setup(struct transformation *t, struct pcoord *c, int scale, int angle)
 343 {
 344         t->pro=c->pro;
 345         t->map_center.x=c->x;
 346         t->map_center.y=c->y;
 347         t->scale=scale;
 348         transform_set_angle(t, angle);
 349 }
 350
 351 #if 0
 352
 353 void
 354 transform_setup_source_rect_limit(struct transformation *t, struct coord *center, int limit)
 355 {
 356         t->center=*center;
 357         t->scale=1;
 358         t->angle=0;
 359         t->r.lu.x=center->x-limit;
 360         t->r.rl.x=center->x+limit;
 361         t->r.rl.y=center->y-limit;
 362         t->r.lu.y=center->y+limit;
 363 }
 364 #endif
 365
 366 void
 367 transform_setup_source_rect(struct transformation *t)
 368 {
 369         int i;
 370         struct coord screen[4];
 371         struct point screen_pnt[4];
 372         struct point_rect *pr;
 373         struct map_selection *ms,*msm,*next,**msm_last;
 374         ms=t->map_sel;
 375         while (ms) {
 376                 next=ms->next;
 377                 g_free(ms);
 378                 ms=next;
 379         }
 380         t->map_sel=NULL;
 381         msm_last=&t->map_sel;
 382         ms=t->screen_sel;
 383         while (ms) {
 384                 msm=g_new0(struct map_selection, 1);
 385                 *msm=*ms;
 386                 pr=&ms->u.p_rect;
 387                 screen_pnt[0].x=pr->lu.x;
 388                 screen_pnt[0].y=pr->lu.y;
 389                 screen_pnt[1].x=pr->rl.x;
 390                 screen_pnt[1].y=pr->lu.y;
 391                 screen_pnt[2].x=pr->lu.x;
 392                 screen_pnt[2].y=pr->rl.y;
 393                 screen_pnt[3].x=pr->rl.x;
 394                 screen_pnt[3].y=pr->rl.y;
 395                 for (i = 0 ; i < 4 ; i++) {
 396                         transform_reverse(t, &screen_pnt[i], &screen[i]);
 397                 }
 398                 msm->u.c_rect.lu.x=min4(screen[0].x,screen[1].x,screen[2].x,screen[3].x);
 399                 msm->u.c_rect.rl.x=max4(screen[0].x,screen[1].x,screen[2].x,screen[3].x);
 400                 msm->u.c_rect.rl.y=min4(screen[0].y,screen[1].y,screen[2].y,screen[3].y);
 401                 msm->u.c_rect.lu.y=max4(screen[0].y,screen[1].y,screen[2].y,screen[3].y);
 402                 *msm_last=msm;
 403                 msm_last=&msm->next;
 404                 ms=ms->next;
 405         }
 406 }
 407
 408 long
 409 transform_get_scale(struct transformation *t)
 410 {
 411         return t->scale;
 412 }
 413
 414 void
 415 transform_set_scale(struct transformation *t, long scale)
 416 {
 417         t->scale=scale;
 418 }
 419
 420
 421 int
 422 transform_get_order(struct transformation *t)
 423 {
 424         int scale=t->scale;
 425         int order=0;
 426         while (scale > 1) {
 427                 order++;
 428                 scale>>=1;
 429         }
 430         order=18-order;
 431         if (order < 0)
 432                 order=0;
 433         return order;
 434 }
 435
 436
 437 void
 438 transform_geo_text(struct coord_geo *g, char *buffer)
 439 {
 440         double lng=g->lng;
 441         double lat=g->lat;
 442         char lng_c='E';
 443         char lat_c='N';
 444
 445         if (lng < 0) {
 446                 lng=-lng;
 447                 lng_c='W';
 448         }
 449         if (lat < 0) {
 450                 lat=-lat;
 451                 lat_c='S';
 452         }
 453
 454         sprintf(buffer,"%02.0f%07.4f%c %03.0f%07.4f%c", floor(lat), fmod(lat*60,60), lat_c, floor(lng), fmod(lng*60,60), lng_c);
 455
 456 }
 457
 458 #define TWOPI (M_PI*2)
 459 #define GC2RAD(c) ((c) * TWOPI/(1<<24))
 460 #define minf(a,b) ((a) < (b) ? (a) : (b))
 461
 462 static double
 463 transform_distance_garmin(struct coord *c1, struct coord *c2)
 464 {
 465 #ifdef USE_HALVESINE
 466         static const int earth_radius = 6371*1000; //m change accordingly
 467 // static const int earth_radius  = 3960; //miles
 468
 469 //Point 1 cords
 470         float lat1  = GC2RAD(c1->y);
 471         float long1 = GC2RAD(c1->x);
 472
 473 //Point 2 cords
 474         float lat2  = GC2RAD(c2->y);
 475         float long2 = GC2RAD(c2->x);
 476
 477 //Haversine Formula
 478         float dlong = long2-long1;
 479         float dlat  = lat2-lat1;
 480
 481         float sinlat  = sinf(dlat/2);
 482         float sinlong = sinf(dlong/2);
 483
 484         float a=(sinlat*sinlat)+cosf(lat1)*cosf(lat2)*(sinlong*sinlong);
 485         float c=2*asinf(minf(1,sqrt(a)));
 486 #ifdef AVOID_FLOAT
 487         return round(earth_radius*c);
 488 #else
 489         return earth_radius*c;
 490 #endif
 491 #else
 492 #define GMETER 2.3887499999999999
 493         double dx,dy;
 494         dx=c1->x-c2->x;
 495         dy=c1->y-c2->y;
 496         return sqrt(dx*dx+dy*dy)*GMETER;
 497 #undef GMETER
 498 #endif
 499 }
 500
 501 double
 502 transform_scale(int y)
 503 {
 504         struct coord c;
 505         struct coord_geo g;
 506         c.x=0;
 507         c.y=y;
 508         transform_to_geo(projection_mg, &c, &g);
 509         return 1/cos(g.lat/180*M_PI);
 510 }
 511
 512 #ifdef AVOID_FLOAT
 513 static int
 514 tab_sqrt[]={14142,13379,12806,12364,12018,11741,11517,11333,11180,11051,10943,10850,10770,10701,10640,10587,10540,10499,10462,10429,10400,10373,10349,10327,10307,10289,10273,10257,10243,10231,10219,10208};
 515 #endif
 516
 517 double
 518 transform_distance(enum projection pro, struct coord *c1, struct coord *c2)
 519 {
 520         if (pro == projection_mg) {
 521 #ifndef AVOID_FLOAT
 522         double dx,dy,scale=transform_scale((c1->y+c2->y)/2);
 523         dx=c1->x-c2->x;
 524         dy=c1->y-c2->y;
 525         return sqrt(dx*dx+dy*dy)/scale;
 526 #else
 527         int dx,dy,f,scale=15539;
 528         dx=c1->x-c2->x;
 529         dy=c1->y-c2->y;
 530         if (dx < 0)
 531                 dx=-dx;
 532         if (dy < 0)
 533                 dy=-dy;
 534         while (dx > 20000 || dy > 20000) {
 535                 dx/=10;
 536                 dy/=10;
 537                 scale/=10;
 538         }
 539         if (! dy)
 540                 return dx*10000/scale;
 541         if (! dx)
 542                 return dy*10000/scale;
 543         if (dx > dy) {
 544                 f=dx*8/dy-8;
 545                 if (f >= 32)
 546                         return dx*10000/scale;
 547                 return dx*tab_sqrt[f]/scale;
 548         } else {
 549                 f=dy*8/dx-8;
 550                 if (f >= 32)
 551                         return dy*10000/scale;
 552                 return dy*tab_sqrt[f]/scale;
 553         }
 554 #endif
 555         } else if (pro == projection_garmin) {
 556                 return transform_distance_garmin(c1, c2);
 557         } else {
 558                 dbg(0,"Unknown projection: %d\n", pro);
 559                 return 0;
 560         }
 561 }
 562
 563 double
 564 transform_polyline_length(enum projection pro, struct coord *c, int count)
 565 {
 566         double ret=0;
 567         int i;
 568
 569         for (i = 0 ; i < count-1 ; i++)
 570                 ret+=transform_distance(pro, &c[i], &c[i+1]);
 571         return ret;
 572 }
 573
 574 int
 575 transform_distance_sq(struct coord *c1, struct coord *c2)
 576 {
 577         int dx=c1->x-c2->x;
 578         int dy=c1->y-c2->y;
 579
 580         if (dx > 32767 || dy > 32767 || dx < -32767 || dy < -32767)
 581                 return INT_MAX;
 582         else
 583                 return dx*dx+dy*dy;
 584 }
 585
 586 int
 587 transform_distance_line_sq(struct coord *l0, struct coord *l1, struct coord *ref, struct coord *lpnt)
 588 {
 589         int vx,vy,wx,wy;
 590         int c1,c2;
 591         int climit=1000000;
 592         struct coord l;
 593
 594         vx=l1->x-l0->x;
 595         vy=l1->y-l0->y;
 596         wx=ref->x-l0->x;
 597         wy=ref->y-l0->y;
 598
 599         c1=vx*wx+vy*wy;
 600         if ( c1 <= 0 ) {
 601                 if (lpnt)
 602                         *lpnt=*l0;
 603                 return transform_distance_sq(l0, ref);
 604         }
 605         c2=vx*vx+vy*vy;
 606         if ( c2 <= c1 ) {
 607                 if (lpnt)
 608                         *lpnt=*l1;
 609                 return transform_distance_sq(l1, ref);
 610         }
 611         while (c1 > climit || c2 > climit) {
 612                 c1/=256;
 613                 c2/=256;
 614         }
 615         l.x=l0->x+vx*c1/c2;
 616         l.y=l0->y+vy*c1/c2;
 617         if (lpnt)
 618                 *lpnt=l;
 619         return transform_distance_sq(&l, ref);
 620 }
 621
 622 int
 623 transform_distance_polyline_sq(struct coord *c, int count, struct coord *ref, struct coord *lpnt, int *pos)
 624 {
 625         int i,dist,distn;
 626         struct coord lp;
 627         if (count < 2)
 628                 return INT_MAX;
 629         if (pos)
 630                 *pos=0;
 631         dist=transform_distance_line_sq(&c[0], &c[1], ref, lpnt);
 632         for (i=2 ; i < count ; i++) {
 633                 distn=transform_distance_line_sq(&c[i-1], &c[i], ref, &lp);
 634                 if (distn < dist) {
 635                         dist=distn;
 636                         if (lpnt)
 637                                 *lpnt=lp;
 638                         if (pos)
 639                                 *pos=i-1;
 640                 }
 641         }
 642         return dist;
 643 }
 644
 645
 646 void
 647 transform_print_deg(double deg)
 648 {
 649         printf("%2.0f:%2.0f:%2.4f", floor(deg), fmod(deg*60,60), fmod(deg*3600,60));
 650 }
 651
 652 #ifdef AVOID_FLOAT
 653 static int tab_atan[]={0,262,524,787,1051,1317,1584,1853,2126,2401,2679,2962,3249,3541,3839,4142,4452,4770,5095,5430,5774,6128,6494,6873,7265,7673,8098,8541,9004,9490,10000,10538};
 654
 655 static int
 656 atan2_int_lookup(int val)
 657 {
 658         int len=sizeof(tab_atan)/sizeof(int);
 659         int i=len/2;
 660         int p=i-1;
 661         for (;;) {
 662                 i>>=1;
 663                 if (val < tab_atan[p])
 664                         p-=i;
 665                 else
 666                         if (val < tab_atan[p+1])
 667                                 return p+(p>>1);
 668                         else
 669                                 p+=i;
 670         }
 671 }
 672
 673 static int
 674 atan2_int(int dx, int dy)
 675 {
 676         int f,mul=1,add=0,ret;
 677         if (! dx) {
 678                 return dy < 0 ? 180 : 0;
 679         }
 680         if (! dy) {
 681                 return dx < 0 ? -90 : 90;
 682         }
 683         if (dx < 0) {
 684                 dx=-dx;
 685                 mul=-1;
 686         }
 687         if (dy < 0) {
 688                 dy=-dy;
 689                 add=180*mul;
 690                 mul*=-1;
 691         }
 692         while (dx > 20000 || dy > 20000) {
 693                 dx/=10;
 694                 dy/=10;
 695         }
 696         if (dx > dy) {
 697                 ret=90-atan2_int_lookup(dy*10000/dx);
 698         } else {
 699                 ret=atan2_int_lookup(dx*10000/dy);
 700         }
 701         return ret*mul+add;
 702 }
 703 #endif
 704
 705 int
 706 transform_get_angle_delta(struct coord *c1, struct coord *c2, int dir)
 707 {
 708         int dx=c2->x-c1->x;
 709         int dy=c2->y-c1->y;
 710 #ifndef AVOID_FLOAT
 711         double angle;
 712         angle=atan2(dx,dy);
 713         angle*=180/M_PI;
 714 #else
 715         int angle;
 716         angle=atan2_int(dx,dy);
 717 #endif
 718         if (dir == -1)
 719                 angle=angle-180;
 720         if (angle < 0)
 721                 angle+=360;
 722         return angle;
 723 }
 724
 725 int
 726 transform_within_border(struct transformation *this_, struct point *p, int border)
 727 {
 728         struct map_selection *ms=this_->screen_sel;
 729         while (ms) {
 730                 struct point_rect *r=&ms->u.p_rect;
 731                 if (p->x >= r->lu.x+border && p->x <= r->rl.x-border &&
 732                     p->y >= r->lu.y+border && p->y <= r->rl.y-border)
 733                         return 1;
 734                 ms=ms->next;
 735         }
 736         return 0;
 737 }
 738
 739 int
 740 transform_within_dist_point(struct coord *ref, struct coord *c, int dist)
 741 {
 742         if (c->x-dist > ref->x)
 743                 return 0;
 744         if (c->x+dist < ref->x)
 745                 return 0;
 746         if (c->y-dist > ref->y)
 747                 return 0;
 748         if (c->y+dist < ref->y)
 749                 return 0;
 750         if ((c->x-ref->x)*(c->x-ref->x) + (c->y-ref->y)*(c->y-ref->y) <= dist*dist)
 751                 return 1;
 752         return 0;
 753 }
 754
 755 int
 756 transform_within_dist_line(struct coord *ref, struct coord *c0, struct coord *c1, int dist)
 757 {
 758         int vx,vy,wx,wy;
 759         int n1,n2;
 760         struct coord lc;
 761
 762         if (c0->x < c1->x) {
 763                 if (c0->x-dist > ref->x)
 764                         return 0;
 765                 if (c1->x+dist < ref->x)
 766                         return 0;
 767         } else {
 768                 if (c1->x-dist > ref->x)
 769                         return 0;
 770                 if (c0->x+dist < ref->x)
 771                         return 0;
 772         }
 773         if (c0->y < c1->y) {
 774                 if (c0->y-dist > ref->y)
 775                         return 0;
 776                 if (c1->y+dist < ref->y)
 777                         return 0;
 778         } else {
 779                 if (c1->y-dist > ref->y)
 780                         return 0;
 781                 if (c0->y+dist < ref->y)
 782                         return 0;
 783         }
 784         vx=c1->x-c0->x;
 785         vy=c1->y-c0->y;
 786         wx=ref->x-c0->x;
 787         wy=ref->y-c0->y;
 788
 789         n1=vx*wx+vy*wy;
 790         if ( n1 <= 0 )
 791                 return transform_within_dist_point(ref, c0, dist);
 792         n2=vx*vx+vy*vy;
 793         if ( n2 <= n1 )
 794                 return transform_within_dist_point(ref, c1, dist);
 795
 796         lc.x=c0->x+vx*n1/n2;
 797         lc.y=c0->y+vy*n1/n2;
 798         return transform_within_dist_point(ref, &lc, dist);
 799 }
 800
 801 int
 802 transform_within_dist_polyline(struct coord *ref, struct coord *c, int count, int close, int dist)
 803 {
 804         int i;
 805         for (i = 0 ; i < count-1 ; i++) {
 806                 if (transform_within_dist_line(ref,c+i,c+i+1,dist)) {
 807                         return 1;
 808                 }
 809         }
 810         if (close)
 811                 return (transform_within_dist_line(ref,c,c+count-1,dist));
 812         return 0;
 813 }
 814
 815 int
 816 transform_within_dist_polygon(struct coord *ref, struct coord *c, int count, int dist)
 817 {
 818         int i, j, ci = 0;
 819         for (i = 0, j = count-1; i < count; j = i++) {
 820                 if ((((c[i].y <= ref->y) && ( ref->y < c[j].y )) ||
 821                 ((c[j].y <= ref->y) && ( ref->y < c[i].y))) &&
 822                 (ref->x < (c[j].x - c[i].x) * (ref->y - c[i].y) / (c[j].y - c[i].y) + c[i].x))
 823                         ci = !ci;
 824         }
 825         if (! ci) {
 826                 if (dist)
 827                         return transform_within_dist_polyline(ref, c, count, dist, 1);
 828                 else
 829                         return 0;
 830         }
 831         return 1;
 832 }
 833
 834 int
 835 transform_within_dist_item(struct coord *ref, enum item_type type, struct coord *c, int count, int dist)
 836 {
 837         if (type < type_line)
 838                 return transform_within_dist_point(ref, c, dist);
 839         if (type < type_area)
 840                 return transform_within_dist_polyline(ref, c, count, 0, dist);
 841         return transform_within_dist_polygon(ref, c, count, dist);
 842 }
 843
 844
 845 /*
 846 Note: there are many mathematically equivalent ways to express these formulas. As usual, not all of them are computationally equivalent.
 847
 848 L = latitude in radians (positive north)
 849 Lo = longitude in radians (positive east)
 850 E = easting (meters)
 851 N = northing (meters)
 852
 853 For the sphere
 854
 855 E = r Lo
 856 N = r ln [ tan (pi/4 + L/2) ]
 857
 858 where
 859
 860 r = radius of the sphere (meters)
 861 ln() is the natural logarithm
 862
 863 For the ellipsoid
 864
 865 E = a Lo
 866 N = a * ln ( tan (pi/4 + L/2) * ( (1 - e * sin (L)) / (1 + e * sin (L))) ** (e/2)  )
 867
 868
 869                                                e
 870                                                -
 871                    pi     L     1 - e sin(L)   2
 872     =  a ln( tan( ---- + ---) (--------------)   )
 873                    4      2     1 + e sin(L)
 874
 875
 876 where
 877
 878 a = the length of the semi-major axis of the ellipsoid (meters)
 879 e = the first eccentricity of the ellipsoid
 880
 881
 882 */
 883
 884