From: Nathan Wagner <nw@hydaspes.if.org>
Date: Mon, 23 Feb 2015 14:03:32 +0000 (+0000)
Subject: work
X-Git-Url: https://pd.if.org/git/?p=hexagon;a=commitdiff_plain;h=e18c84c99d50c450bcbe8ad8f66d4e57eadf0911

work
---

diff --git a/pgsql/hexfuncs.sql b/pgsql/hexfuncs.sql
index 8826e17..b080539 100644
--- a/pgsql/hexfuncs.sql
+++ b/pgsql/hexfuncs.sql
@@ -5,6 +5,41 @@ create schema hex;
 
 set search_path to hex,public,gis;
 
+-- return a postgis text polygon
+-- the 0,0 hex center is at the origin
+-- we rotate, then translate
+create or replace function hexgeom(
+	xc integer, yc integer, scale float = 1.0, angle float = 0.0, xorigin float = 0.0, yorigin float = 0.0
+) returns text language 'plpgsql' as $$
+declare
+	x float[];
+	y float[];
+	stride float;
+	xoff float;
+	yoff float;
+begin
+	stride := scale * 2.0 / sqrt(3.0);
+	xoff := stride;
+	yoff = scale / 2.0;
+	x[1] := (2 + 3 * xc ) * stride;
+	x[4] := (-2 + 3 * xc) * stride;
+	x[2] := (1 + 3 * xc ) * stride;
+	x[6] := (1 + 3 * xc ) * stride;
+	x[3] := (-1 + 3 * xc ) * stride;
+	x[5] := (-1 + 3 * xc ) * stride;
+
+	y[1] := (0 + 2 * yc + xc % 2) * yoff;
+	y[4] := (0 + 2 * yc + xc % 2) * yoff;
+	y[2] := (1 + 2 * yc + xc % 2) * yoff;
+	y[3] := (1 + 2 * yc + xc % 2) * yoff;
+	y[5] := (-1 + 2 * yc + xc % 2) * yoff;
+	y[6] := (-1 + 2 * yc + xc % 2) * yoff;
+
+	return format('POLYGON((%s %s, %s %s, %s %s, %s %s, %s %s, %s %s))',
+		x[1], y[1], x[2], y[2], x[3], y[3], x[4], y[4], x[5], y[5], x[6], y[6]);
+end;
+$$ immutable strict;
+
 create or replace function hexgrid(
 	xdim integer,
 	ydim integer,