MySQL implementation of ray-casting Algorithm?

Question

We need to figure out a quick and fairly accurate method for point-in-polygon for lat/long values and polygons over google maps. After some research - came across some posts abo

Answer 1

I wanted to use the above mywithin stored procedure on a table of polygons so here are the commands to do just that.

After importing a shapefile containing polygons into mysql using ogr2ogr as follows

ogr2ogr -f "mysql" MYSQL:"mydbname,host=localhost,user=root,password=mypassword,port=3306" -nln "mytablename" -a_srs "EPSG:4326" /path/to/shapefile.shp

you can then use MBRwithin to prefilter your table and mywithin to finish as follows

DROP TEMPORARY TABLE IF EXISTS POSSIBLE_POLYS;
CREATE TEMPORARY TABLE POSSIBLE_POLYS(OGR_FID INT,SHAPE POLYGON);
INSERT INTO POSSIBLE_POLYS (OGR_FID, SHAPE) SELECT mytablename.OGR_FID,mytablename.SHAPE FROM mytablename WHERE MBRwithin(@testpoint,mytablename.SHAPE);

DROP TEMPORARY TABLE IF EXISTS DEFINITE_POLY;
CREATE TEMPORARY TABLE DEFINITE_POLY(OGR_FID INT,SHAPE POLYGON);
INSERT INTO DEFINITE_POLY (OGR_FID, SHAPE) SELECT POSSIBLE_POLYS.OGR_FID,POSSIBLE_POLYS.SHAPE FROM POSSIBLE_POLYS WHERE mywithin(@testpoint,POSSIBLE_POLYS.SHAPE);

where @testpoint is created, for example, from

SET @longitude=120;
SET @latitude=-30;
SET @testpoint =(PointFromText( concat( "POINT(", @longitude, " ", @latitude, ")" ) ));