open source gis - Get all vertices of a polygon using OGR and Python

I'm having a little trouble with the Python OGR API. What I am trying to do is get all the coordinates of each vertex of the outer ring of a polygon.

This is what I have so far:

import osgeo.ogr
import glob

path = "/home/woo/maps/"
out = path + 'output.txt'

file = open(out,'w')
for filename in glob.glob(path + "*.shp"):

    ds = osgeo.ogr.Open(filename)
    layer1 = ds.GetLayer(0)
    print layer1.GetExtent()    
    for feat in layer1:
        geom = feat.GetGeometryRef()
        ring = geom.GetGeometryRef(0)
        points = ring.GetPointCount()
        #Not sure what to do here



file.close()

I have heard that you can just for over the region but that only returns the rings in the polygon, not the nodes.

Anyone able to help.

Answer

It depends a bit on your file format and geometry, but in principle the continuation could look like this.

  for p in xrange(points):
        lon, lat, z = ring.GetPoint(p)