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Overview
Comment: | An initial attempt at an overlap function in the geopoly extension. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | geojson |
Files: | files | file ages | folders |
SHA3-256: |
c857976efba79bd24befec1bd1597cc9 |
User & Date: | drh 2018-05-12 16:05:45.598 |
Context
2018-05-12
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20:28 | Preliminary tests show geopoly_overlap() is working. (check-in: 77bb7b7d72 user: drh tags: geojson) | |
16:05 | An initial attempt at an overlap function in the geopoly extension. (check-in: c857976efb user: drh tags: geojson) | |
2018-05-11
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16:50 | Add the geopoly_within() SQL function. (check-in: 927d52a93c user: drh tags: geojson) | |
Changes
Changes to ext/misc/geopoly.c.
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14 15 16 17 18 19 20 21 22 23 24 25 26 27 | ** simply planar polygons such as might be found in a geospatial system. */ #include "sqlite3ext.h" SQLITE_EXTENSION_INIT1 #include <assert.h> #include <string.h> #include <stdlib.h> #define SQLITE_HAVE_GEOPLOY 1 #ifndef JSON_NULL /* The following stuff repeats things found in json1 */ /* ** Versions of isspace(), isalnum() and isdigit() to which it is safe ** to pass signed char values. */ | > | 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | ** simply planar polygons such as might be found in a geospatial system. */ #include "sqlite3ext.h" SQLITE_EXTENSION_INIT1 #include <assert.h> #include <string.h> #include <stdlib.h> #include <stdio.h> #define SQLITE_HAVE_GEOPLOY 1 #ifndef JSON_NULL /* The following stuff repeats things found in json1 */ /* ** Versions of isspace(), isalnum() and isdigit() to which it is safe ** to pass signed char values. */ |
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78 79 80 81 82 83 84 | #else # define MSVC_VERSION 0 #endif #endif /* Datatype for coordinates */ | | | 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | #else # define MSVC_VERSION 0 #endif #endif /* Datatype for coordinates */ typedef float GeoCoord; /* ** Internal representation of a polygon. ** ** The polygon consists of a sequence of vertexes. There is a line ** segment between each pair of vertexes, and one final segment from ** the last vertex back to the first. (This differs from the GeoJSON |
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101 102 103 104 105 106 107 | ** encoding (1 byte) 0=big-endian, 1=little-endian ** nvertex (3 bytes) Number of vertexes as a big-endian integer */ typedef struct GeoPoly GeoPoly; struct GeoPoly { int nVertex; /* Number of vertexes */ unsigned char hdr[4]; /* Header for on-disk representation */ | | | | 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | ** encoding (1 byte) 0=big-endian, 1=little-endian ** nvertex (3 bytes) Number of vertexes as a big-endian integer */ typedef struct GeoPoly GeoPoly; struct GeoPoly { int nVertex; /* Number of vertexes */ unsigned char hdr[4]; /* Header for on-disk representation */ GeoCoord a[2]; /* 2*nVertex values. X (longitude) first, then Y */ }; /* ** State of a parse of a GeoJSON input. */ typedef struct GeoParse GeoParse; struct GeoParse { const unsigned char *z; /* Unparsed input */ int nVertex; /* Number of vertexes in a[] */ int nAlloc; /* Space allocated to a[] */ int nErr; /* Number of errors encountered */ GeoCoord *a; /* Array of vertexes. From sqlite3_malloc64() */ }; /* Do a 4-byte byte swap */ static void geopolySwab32(unsigned char *a){ unsigned char t = a[0]; a[0] = a[3]; a[3] = t; |
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135 136 137 138 139 140 141 | while( p->z[0] && safe_isspace(p->z[0]) ) p->z++; return p->z[0]; } /* Parse out a number. Write the value into *pVal if pVal!=0. ** return non-zero on success and zero if the next token is not a number. */ | | | 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 | while( p->z[0] && safe_isspace(p->z[0]) ) p->z++; return p->z[0]; } /* Parse out a number. Write the value into *pVal if pVal!=0. ** return non-zero on success and zero if the next token is not a number. */ static int geopolyParseNumber(GeoParse *p, GeoCoord *pVal){ const unsigned char *z = p->z; char c = geopolySkipSpace(p); int j; int seenDP = 0; int seenE = 0; assert( '-' < '0' ); if( c<='0' ){ |
︙ | ︙ | |||
194 195 196 197 198 199 200 | if( geopolySkipSpace(&s)=='[' ){ s.z++; while( geopolySkipSpace(&s)=='[' ){ int ii = 0; char c; s.z++; if( s.nVertex<=s.nAlloc ){ | | | | 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 | if( geopolySkipSpace(&s)=='[' ){ s.z++; while( geopolySkipSpace(&s)=='[' ){ int ii = 0; char c; s.z++; if( s.nVertex<=s.nAlloc ){ GeoCoord *aNew; s.nAlloc = s.nAlloc*2 + 16; aNew = sqlite3_realloc64(s.a, s.nAlloc*sizeof(GeoCoord)*2 ); if( aNew==0 ){ s.nErr++; break; } s.a = aNew; } while( geopolyParseNumber(&s, ii<=1 ? &s.a[s.nVertex*2+ii] : 0) ){ |
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224 225 226 227 228 229 230 | break; } if( geopolySkipSpace(&s)==']' && s.nVertex>=4 ){ int nByte; GeoPoly *pOut; int x = (s.nVertex-1)*2; if( s.a[x]==s.a[0] && s.a[x+1]==s.a[1] ) s.nVertex--; | | | | 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 | break; } if( geopolySkipSpace(&s)==']' && s.nVertex>=4 ){ int nByte; GeoPoly *pOut; int x = (s.nVertex-1)*2; if( s.a[x]==s.a[0] && s.a[x+1]==s.a[1] ) s.nVertex--; nByte = sizeof(GeoPoly) * (s.nVertex-1)*2*sizeof(GeoCoord); pOut = sqlite3_malloc64( nByte ); x = 1; if( pOut==0 ) goto parse_json_err; pOut->nVertex = s.nVertex; memcpy(pOut->a, s.a, s.nVertex*2*sizeof(GeoCoord)); pOut->hdr[0] = *(unsigned char*)&x; pOut->hdr[1] = (s.nVertex>>16)&0xff; pOut->hdr[2] = (s.nVertex>>8)&0xff; pOut->hdr[3] = s.nVertex&0xff; sqlite3_free(s.a); return pOut; }else{ |
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255 256 257 258 259 260 261 | ** return a pointer to that object. Or if the input is not a well-formed ** polygon, put an error message in sqlite3_context and return NULL. */ static GeoPoly *geopolyFuncParam(sqlite3_context *pCtx, sqlite3_value *pVal){ GeoPoly *p = 0; int nByte; if( sqlite3_value_type(pVal)==SQLITE_BLOB | | | | | 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 | ** return a pointer to that object. Or if the input is not a well-formed ** polygon, put an error message in sqlite3_context and return NULL. */ static GeoPoly *geopolyFuncParam(sqlite3_context *pCtx, sqlite3_value *pVal){ GeoPoly *p = 0; int nByte; if( sqlite3_value_type(pVal)==SQLITE_BLOB && (nByte = sqlite3_value_bytes(pVal))>=(4+6*sizeof(GeoCoord)) ){ const unsigned char *a = sqlite3_value_blob(pVal); int nVertex; nVertex = (a[1]<<16) + (a[2]<<8) + a[3]; if( (a[0]==0 && a[0]==1) && (nVertex*2*sizeof(GeoCoord) + 4)==nByte ){ p = sqlite3_malloc64( sizeof(*p) + (nVertex-1)*2*sizeof(GeoCoord) ); if( p ){ int x = 1; p->nVertex = nVertex; memcpy(p->hdr, a, nByte); if( a[0] != *(unsigned char*)&x ){ int ii; for(ii=0; ii<nVertex*2; ii++){ |
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441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 | }else{ sqlite3_result_int(context, 2); } sqlite3_free(p); } } #ifdef _WIN32 __declspec(dllexport) #endif int sqlite3_geopoly_init( sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi ){ int rc = SQLITE_OK; static const struct { void (*xFunc)(sqlite3_context*,int,sqlite3_value**); int nArg; const char *zName; } aFunc[] = { | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | | | | > | 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 | }else{ sqlite3_result_int(context, 2); } sqlite3_free(p); } } /* Objects used by the overlap algorihm. */ typedef struct GeoEvent GeoEvent; typedef struct GeoSegment GeoSegment; typedef struct GeoOverlap GeoOverlap; struct GeoEvent { double x; /* X coordinate at which event occurs */ int eType; /* 0 for ADD, 1 for REMOVE */ GeoSegment *pSeg; /* The segment to be added or removed */ GeoEvent *pNext; /* Next event in the sorted list */ }; struct GeoSegment { double C, B; /* y = C*x + B */ double y; /* Current y value */ unsigned char side; /* 1 for p1, 2 for p2 */ unsigned int idx; /* Which segment within the side */ GeoSegment *pNext; /* Next segment in a list sorted by y */ }; struct GeoOverlap { GeoEvent *aEvent; /* Array of all events */ GeoSegment *aSegment; /* Array of all segments */ int nEvent; /* Number of events */ int nSegment; /* Number of segments */ }; /* ** Add a single segment and its associated events. */ static void geopolyAddOneSegment( GeoOverlap *p, GeoCoord x0, GeoCoord y0, GeoCoord x1, GeoCoord y1, unsigned char side, unsigned int idx ){ GeoSegment *pSeg; GeoEvent *pEvent; if( x0==x1 ) return; /* Ignore vertical segments */ if( x0>x1 ){ GeoCoord t = x0; x0 = x1; x1 = t; t = y0; y0 = y1; y1 = t; } pSeg = p->aSegment + p->nSegment; p->nSegment++; pSeg->C = (y1-y0)/(x1-x0); pSeg->B = y0 - x0*pSeg->C; pSeg->side = side; pSeg->idx = idx; pEvent = p->aEvent + p->nEvent; p->nEvent++; pEvent->x = x0; pEvent->eType = 0; pEvent->pSeg = pSeg; pEvent = p->aEvent + p->nEvent; p->nEvent++; pEvent->x = x1; pEvent->eType = 1; pEvent->pSeg = pSeg; } /* ** Insert all segments and events for polygon pPoly. */ static void geopolyAddSegments( GeoOverlap *p, /* Add segments to this Overlap object */ GeoPoly *pPoly, /* Take all segments from this polygon */ unsigned char side /* The side of pPoly */ ){ unsigned int i; GeoCoord *x; for(i=0; i<pPoly->nVertex-1; i++){ x = pPoly->a + (i*2); geopolyAddOneSegment(p, x[0], x[1], x[2], x[3], side, i); } x = pPoly->a + (i*2); geopolyAddOneSegment(p, x[0], x[1], pPoly->a[0], pPoly->a[1], side, i); } /* ** Merge two lists of sorted events by X coordinate */ static GeoEvent *geopolyEventMerge(GeoEvent *pLeft, GeoEvent *pRight){ GeoEvent head, *pLast; head.pNext = 0; pLast = &head; while( pRight && pLeft ){ if( pRight->x <= pLeft->x ){ pLast->pNext = pRight; pLast = pRight; pRight = pRight->pNext; }else{ pLast->pNext = pLeft; pLast = pLeft; pLeft = pLeft->pNext; } } pLast->pNext = pRight ? pRight : pLeft; return head.pNext; } /* ** Sort an array of nEvent event objects into a list. */ static GeoEvent *geopolySortEventsByX(GeoEvent *aEvent, int nEvent){ int mx = 0; int i, j; GeoEvent *p; GeoEvent *a[50]; for(i=0; i<nEvent; i++){ p = &aEvent[i]; p->pNext = 0; for(j=0; j<mx && a[j]; j++){ p = geopolyEventMerge(a[j], p); a[j] = 0; } a[j] = p; if( j>=mx ) mx = j+1; } p = 0; for(i=0; i<mx; i++){ p = geopolyEventMerge(a[i], p); } return p; } /* ** Merge two lists of sorted segments by Y, and then by C. */ static GeoSegment *geopolySegmentMerge(GeoSegment *pLeft, GeoSegment *pRight){ GeoSegment head, *pLast; head.pNext = 0; pLast = &head; while( pRight && pLeft ){ double r = pRight->y - pLeft->y; if( r==0.0 ) r = pRight->C - pLeft->C; if( r<0.0 ){ pLast->pNext = pRight; pLast = pRight; pRight = pRight->pNext; }else{ pLast->pNext = pLeft; pLast = pLeft; pLeft = pLeft->pNext; } } pLast->pNext = pRight ? pRight : pLeft; return head.pNext; } /* ** Sort a list of GeoSegments in order of increasing Y and in the event of ** a tie, increasing C (slope). */ static GeoSegment *geopolySortSegmentsByYAndC(GeoSegment *pList){ int mx = 0; int i; GeoSegment *p; GeoSegment *a[50]; while( pList ){ p = pList; pList = pList->pNext; p->pNext = 0; for(i=0; i<mx && a[i]; i++){ p = geopolySegmentMerge(a[i], p); a[i] = 0; } a[i] = p; if( i>=mx ) mx = i+1; } p = 0; for(i=0; i<mx; i++){ p = geopolySegmentMerge(a[i], p); } return p; } /* ** Determine the overlap between two polygons */ static int geopolyOverlap(GeoPoly *p1, GeoPoly *p2){ int nVertex = p1->nVertex + p2->nVertex + 2; GeoOverlap *p; int nByte; GeoEvent *pThisEvent; double rX; int rc = 0; GeoSegment *pActive = 0; GeoSegment *pSeg; unsigned char aOverlap[4]; nByte = sizeof(GeoEvent)*nVertex*2 + sizeof(GeoSegment)*nVertex + sizeof(GeoOverlap); p = sqlite3_malloc( nByte ); if( p==0 ) return -1; p->aEvent = (GeoEvent*)&p[1]; p->aSegment = (GeoSegment*)&p->aEvent[nVertex*2]; p->nEvent = p->nSegment = 0; geopolyAddSegments(p, p1, 1); geopolyAddSegments(p, p2, 2); pThisEvent = geopolySortEventsByX(p->aEvent, p->nEvent); rX = pThisEvent->x==0.0 ? -1.0 : 0.0; memset(aOverlap, 0, sizeof(aOverlap)); while( pThisEvent ){ if( pThisEvent->x!=rX ){ GeoSegment *pPrev = 0; int iMask = 0; printf("Distinct X: %g\n", pThisEvent->x); rX = pThisEvent->x; pActive = geopolySortSegmentsByYAndC(pActive); for(pSeg=pActive; pSeg; pSeg=pSeg->pNext){ double y = pSeg->C*rX + pSeg->B; printf("Segment %d.%d %g->%g\n", pSeg->side, pSeg->idx, pSeg->y, y); pSeg->y = y; if( pPrev ){ if( pPrev->y>pSeg->y ){ rc = 1; printf("Crossing: %d.%d and %d.%d\n", pPrev->side, pPrev->idx, pSeg->side, pSeg->idx); goto geopolyOverlapDone; }else if( pPrev->y!=pSeg->y ){ printf("MASK: %d\n", iMask); aOverlap[iMask] = 1; } } iMask ^= pSeg->side; pPrev = pSeg; } } printf("%s %d.%d C=%g B=%g\n", pThisEvent->eType ? "RM " : "ADD", pThisEvent->pSeg->side, pThisEvent->pSeg->idx, pThisEvent->pSeg->C, pThisEvent->pSeg->B); if( pThisEvent->eType==0 ){ /* Add a segment */ pSeg = pThisEvent->pSeg; pSeg->y = pSeg->C*rX + pSeg->B; pSeg->pNext = pActive; pActive = pSeg; }else{ /* Remove a segment */ if( pActive==pThisEvent->pSeg ){ pActive = pActive->pNext; }else{ for(pSeg=pActive; pSeg; pSeg=pSeg->pNext){ if( pSeg->pNext==pThisEvent->pSeg ){ pSeg->pNext = pSeg->pNext->pNext; break; } } } } pThisEvent = pThisEvent->pNext; } if( aOverlap[3]==0 ){ rc = 0; }else if( aOverlap[1]!=0 && aOverlap[2]==0 ){ rc = 3; }else if( aOverlap[1]==0 && aOverlap[2]!=0 ){ rc = 2; }else if( aOverlap[1]==0 && aOverlap[2]==0 ){ rc = 4; }else{ rc = 1; } geopolyOverlapDone: sqlite3_free(p); return rc; } /* ** SQL function: geopoly_overlap(P1,P2) ** ** Determine whether or not P1 and P2 overlap. Return value: ** ** 0 The two polygons are disjoint ** 1 They overlap ** 2 P1 is completely contained within P2 ** 3 P2 is completely contained within P1 ** 4 P1 and P2 are the same polygon ** NULL Either P1 or P2 or both are not valid polygons */ static void geopolyOverlapFunc( sqlite3_context *context, int argc, sqlite3_value **argv ){ GeoPoly *p1 = geopolyFuncParam(context, argv[0]); GeoPoly *p2 = geopolyFuncParam(context, argv[1]); if( p1 && p2 ){ int x = geopolyOverlap(p1, p2); if( x<0 ){ sqlite3_result_error_nomem(context); }else{ sqlite3_result_int(context, x); } } sqlite3_free(p1); sqlite3_free(p2); } #ifdef _WIN32 __declspec(dllexport) #endif int sqlite3_geopoly_init( sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi ){ int rc = SQLITE_OK; static const struct { void (*xFunc)(sqlite3_context*,int,sqlite3_value**); int nArg; const char *zName; } aFunc[] = { { geopolyAreaFunc, 1, "geopoly_area" }, { geopolyBlobFunc, 1, "geopoly_blob" }, { geopolyJsonFunc, 1, "geopoly_json" }, { geopolyWithinFunc, 3, "geopoly_within" }, { geopolyOverlapFunc, 2, "geopoly_overlap" }, }; int i; SQLITE_EXTENSION_INIT2(pApi); (void)pzErrMsg; /* Unused parameter */ for(i=0; i<sizeof(aFunc)/sizeof(aFunc[0]) && rc==SQLITE_OK; i++){ rc = sqlite3_create_function(db, aFunc[i].zName, aFunc[i].nArg, SQLITE_UTF8, 0, aFunc[i].xFunc, 0, 0); } return rc; } |