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Overview
| Comment: | Replace the new geopoly_reverse() function with geopoly_ccw(). The geopoly_ccw() function only reverses the vertex order if doing so is necessary to get the correct right-hand winding rule on the polygon. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
075066944b13b18d339ccf87ae16f0b9 |
| User & Date: | drh 2018-10-08 18:55:56.767 |
Context
|
2018-10-08
| ||
| 20:04 | Fix an issue with the new memstat.c extension. (check-in: ce6e80b130 user: drh tags: trunk) | |
| 18:55 | Replace the new geopoly_reverse() function with geopoly_ccw(). The geopoly_ccw() function only reverses the vertex order if doing so is necessary to get the correct right-hand winding rule on the polygon. (check-in: 075066944b user: drh tags: trunk) | |
| 12:58 | Add the geopoly_reverse() function to the GeoPoly extension. (check-in: 690dd18a57 user: drh tags: trunk) | |
Changes
Changes to ext/rtree/geopoly.c.
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p->a[ii*2+1] = y1;
}
sqlite3_result_blob(context, p->hdr,
4+8*p->nVertex, SQLITE_TRANSIENT);
sqlite3_free(p);
}
}
/*
** Implementation of the geopoly_area(X) function.
**
** If the input is a well-formed Geopoly BLOB then return the area
** enclosed by the polygon. If the polygon circulates clockwise instead
** of counterclockwise (as it should) then return the negative of the
** enclosed area. Otherwise return NULL.
*/
static void geopolyAreaFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
GeoPoly *p = geopolyFuncParam(context, argv[0], 0);
if( p ){
| > > > > > > > > > > > > > > > > > > > > > < < < < < < < < < < | | > > | > > > > | | | > | | | | | | | | | | 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 |
p->a[ii*2+1] = y1;
}
sqlite3_result_blob(context, p->hdr,
4+8*p->nVertex, SQLITE_TRANSIENT);
sqlite3_free(p);
}
}
/*
** Compute the area enclosed by the polygon.
**
** This routine can also be used to detect polygons that rotate in
** the wrong direction. Polygons are suppose to be counter-clockwise (CCW).
** This routine returns a negative value for clockwise (CW) polygons.
*/
static double geopolyArea(GeoPoly *p){
double rArea = 0.0;
int ii;
for(ii=0; ii<p->nVertex-1; ii++){
rArea += (p->a[ii*2] - p->a[ii*2+2]) /* (x0 - x1) */
* (p->a[ii*2+1] + p->a[ii*2+3]) /* (y0 + y1) */
* 0.5;
}
rArea += (p->a[ii*2] - p->a[0]) /* (xN - x0) */
* (p->a[ii*2+1] + p->a[1]) /* (yN + y0) */
* 0.5;
return rArea;
}
/*
** Implementation of the geopoly_area(X) function.
**
** If the input is a well-formed Geopoly BLOB then return the area
** enclosed by the polygon. If the polygon circulates clockwise instead
** of counterclockwise (as it should) then return the negative of the
** enclosed area. Otherwise return NULL.
*/
static void geopolyAreaFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
GeoPoly *p = geopolyFuncParam(context, argv[0], 0);
if( p ){
sqlite3_result_double(context, geopolyArea(p));
sqlite3_free(p);
}
}
/*
** Implementation of the geopoly_ccw(X) function.
**
** If the rotation of polygon X is clockwise (incorrect) instead of
** counter-clockwise (the correct winding order according to RFC7946)
** then reverse the order of the vertexes in polygon X.
**
** In other words, this routine returns a CCW polygon regardless of the
** winding order of its input.
**
** Use this routine to sanitize historical inputs that that sometimes
** contain polygons that wind in the wrong direction.
*/
static void geopolyCcwFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
GeoPoly *p = geopolyFuncParam(context, argv[0], 0);
if( p ){
if( geopolyArea(p)<0.0 ){
int ii, jj;
for(ii=2, jj=p->nVertex*2 - 4; ii<jj; ii+=2, jj-=2){
GeoCoord t = p->a[ii];
p->a[ii] = p->a[jj];
p->a[jj] = t;
t = p->a[ii+1];
p->a[ii+1] = p->a[jj+1];
p->a[jj+1] = t;
}
}
sqlite3_result_blob(context, p->hdr,
4+8*p->nVertex, SQLITE_TRANSIENT);
sqlite3_free(p);
}
}
|
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{ geopolyWithinFunc, 2, 1, "geopoly_within" },
{ geopolyContainsPointFunc, 3, 1, "geopoly_contains_point" },
{ geopolyOverlapFunc, 2, 1, "geopoly_overlap" },
{ geopolyDebugFunc, 1, 0, "geopoly_debug" },
{ geopolyBBoxFunc, 1, 1, "geopoly_bbox" },
{ geopolyXformFunc, 7, 1, "geopoly_xform" },
{ geopolyRegularFunc, 4, 1, "geopoly_regular" },
| | | 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 |
{ geopolyWithinFunc, 2, 1, "geopoly_within" },
{ geopolyContainsPointFunc, 3, 1, "geopoly_contains_point" },
{ geopolyOverlapFunc, 2, 1, "geopoly_overlap" },
{ geopolyDebugFunc, 1, 0, "geopoly_debug" },
{ geopolyBBoxFunc, 1, 1, "geopoly_bbox" },
{ geopolyXformFunc, 7, 1, "geopoly_xform" },
{ geopolyRegularFunc, 4, 1, "geopoly_regular" },
{ geopolyCcwFunc, 1, 1, "geopoly_ccw" },
};
static const struct {
void (*xStep)(sqlite3_context*,int,sqlite3_value**);
void (*xFinal)(sqlite3_context*);
const char *zName;
} aAgg[] = {
{ geopolyBBoxStep, geopolyBBoxFinal, "geopoly_group_bbox" },
|
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