This is a solution for polygon selection in google maps. Some polygons can across antimeridian which will be getting wrong by postgis when you make ST_Within query, for example. So, this function allows to split polygon to multipolygon, parts of wich are contained in both hemispheres if needs

google_maps_polygon.py

# -*- coding: utf-8 -*-
from django.contrib.gis.geos import MultiPolygon, GEOSGeometry
from django.db import connection


def is_crossed_antimeridian(polygon):
    crossed = False
    coords = []
    for polygon_set in polygon:
        for (lng, lat) in polygon_set:
            coords.append(lng)
    current_lng = coords.pop(0)
    for coord in coords:
        if abs(current_lng-coord) > 180:
            return True
        current_lng = coord
    return crossed


def split_polygon_by_antimeridian(polygon):
    """
    Function split polygon to Multipolygon by antimeridian
    :param polygon: Polygon
    :return: Multipolygon 
    """
    if not is_crossed_antimeridian(polygon):
        return MultiPolygon(polygon, srid=polygon.srid)
    srid = polygon.srid,
    wkt = polygon.wkt
    with connection.cursor() as cursor:
        cursor.execute("""
        SELECT ST_Union(

                ST_Multi(
                    ST_Intersection(
                        ST_MakeEnvelope(0, -90, 180, 90, %s),
                        ST_MakeValid(ST_ShiftLongitude(ST_GeomFromText(%s, %s)))
                    )
                )
                ,
                ST_Translate(
                    ST_Multi(
                        ST_Intersection(
                            ST_MakeEnvelope(180, -90, 360, 90, %s),
                            ST_MakeValid(ST_ShiftLongitude(ST_GeomFromText(%s, %s)))
                        )
                    ), -360, 0
                )
        )
        """, (srid, wkt, srid, srid, wkt, srid))
        row = cursor.fetchone()
        return GEOSGeometry(row[0])

Thanks for this. It mostly worked for me except for the whether it crosses the prime meridian. I think your function will work if it crosses the prime meridian on a short segment, but not if it wraps around much of the world.

Here's what I ended up with:

    def crosses_prime_meridian?(min, max)
      min = min + 360 if min < 0
      max = max + 360 if max < 0
      min < 180 && max >180 ||
        min < 180 && max < min ||
        min > 180 && max > 180 && min > max
    end

My problem space was slightly different since I knew I was always moving left to right and only dealing with a line segment not a polygon.

Anyway, thanks for posting this. Saved me a bunch of time.

Thanks for you feedback it is nice to know that your work has helped somebody.