int msIntersectPolygons(shapeObj *p1, shapeObj *p2)
{
int i;
/* STEP 1: polygon 1 completely contains 2 (only need to check one point from each part) */
for(i=0; i<p2->numlines; i++) {
if(msIntersectPointPolygon(&(p2->line[i].point[0]), p1) == MS_TRUE) /* this considers holes and multiple parts */
return(MS_TRUE);
}
/* STEP 2: polygon 2 completely contains 1 (only need to check one point from each part) */
for(i=0; i<p1->numlines; i++) {
if(msIntersectPointPolygon(&(p1->line[i].point[0]), p2) == MS_TRUE) /* this considers holes and multiple parts */
return(MS_TRUE);
}
/* STEP 3: look for intersecting line segments */
if (msIntersectPolylines(p1, p2) == MS_TRUE)
return(MS_TRUE);
/*
** At this point we know there are are no intersections between edges. There may be other tests necessary
** but I haven't run into any cases that require them.
*/
return(MS_FALSE);
}
int msIntersectPolylinePolygon(shapeObj *line, shapeObj *poly) {
int i;
/* STEP 1: polygon might competely contain the polyline or one of it's parts (only need to check one point from each part) */
for(i=0; i<line->numlines; i++) {
if(msIntersectPointPolygon(&(line->line[i].point[0]), poly) == MS_TRUE) /* this considers holes and multiple parts */
return(MS_TRUE);
}
/* STEP 2: look for intersecting line segments */
if (msIntersectPolylines(line, poly) == MS_TRUE)
return (MS_TRUE);
return(MS_FALSE);
}
/*
** Does shape1 intersect shape2, returns MS_TRUE/MS_FALSE or -1 for an error.
*/
int msGEOSIntersects(shapeObj *shape1, shapeObj *shape2)
{
#ifdef USE_GEOS
GEOSGeom g1, g2;
int result;
if(!shape1 || !shape2)
return -1;
if(!shape1->geometry) /* if no geometry for shape1 then build one */
shape1->geometry = (GEOSGeom) msGEOSShape2Geometry(shape1);
g1 = (GEOSGeom) shape1->geometry;
if(!g1) return -1;
if(!shape2->geometry) /* if no geometry for shape2 then build one */
shape2->geometry = (GEOSGeom) msGEOSShape2Geometry(shape2);
g2 = (GEOSGeom) shape2->geometry;
if(!g2) return -1;
result = GEOSIntersects(g1, g2);
return ((result==2) ? -1 : result);
#else
if(!shape1 || !shape2)
return -1;
switch(shape1->type) { /* todo: deal with point shapes */
case(MS_SHAPE_LINE):
switch(shape2->type) {
case(MS_SHAPE_LINE):
return msIntersectPolylines(shape1, shape2);
case(MS_SHAPE_POLYGON):
return msIntersectPolylinePolygon(shape1, shape2);
}
break;
case(MS_SHAPE_POLYGON):
switch(shape2->type) {
case(MS_SHAPE_LINE):
return msIntersectPolylinePolygon(shape2, shape1);
case(MS_SHAPE_POLYGON):
return msIntersectPolygons(shape1, shape2);
}
break;
}
return -1;
#endif
}
