Documentation Source Text

either the GeoJSON format or the internal binary format.

<tcl>hd_fragment goverlap geopoly_overlap</tcl>
<h2>The geopoly_overlap(P1,P2) Function</h2>

<p>
If P1 and P2 are both polygons, then the geopoly_overlap(P1,P2) function returns
a non-zero integer if there is any overlap between P1 and P2, or it returns
zero if P1 and P2 completely disjoint.
If either P1 or P2 is not a polygon, this routine returns NULL.

<p>
The geopoly_overlap(P1,P2) function is special in that the geopoly virtual
table knows how to use R*Tree indexes to optimize queries in which the 
WHERE clause uses geopoly_overlap() as a boolean function.  Only the
geopoly_overlap(P1,P2) and geopoly_within(P1,P2) functions have this
capability.

<tcl>hd_fragment gwithin geopoly_within</tcl>
<h2>The geopoly_within(P1,P2) Function</h2>

<p>
If P1 and P2 are both polygons, then the geopoly_within(P1,P2) function returns
a non-zero integer if P2 is completely contained within P1, or it returns zero
if any part of P2 is outside of P1.  If P1 and P2 are the same polygon, this routine
returns non-zero.
If either P1 or P2 is not a polygon, this routine returns NULL.

<p>
The geopoly_within(P1,P2) function is special in that the geopoly virtual
table knows how to use R*Tree indexes to optimize queries in which the 
WHERE clause uses geopoly_within() as a boolean function.  Only the
geopoly_within(P1,P2) and geopoly_overlap(P1,P2) functions have this

The geopoly_group_bbox(P) function returns the smallest rectangle that will
enclose all P values seen during aggregation.

<tcl>hd_fragment gpoint geopoly_constains_point</tcl>
<h2>The geopoly_contains_point(P,X,Y) Function</h2>

<p>
If P is a polygon, then geopoly_contains_point(P,X,Y) returns a 
non-zero integer if and only
if the coordinate X,Y is inside or on the boundary of the polygon P.
If P is not a polygon, geopoly_contains_point(P,X,Y) returns NULL.

<tcl>hd_fragment xform geopoly_xform</tcl>
<h2>The geopoly_xform(P,A,B,C,D,E,F) Function</h2>

<p>