genazlines.py

import math
from qgis.core import *

from processing.core.VectorWriter import VectorWriter

##degspacing=number 30
##distance=number 5000000
##numrings=number 4
##centerx=number 0.0
##centery=number 0.0
##output=output vector
##crsId=string USER:100001

def mkpoint(start, distance, bearing):
    # bearing in radians
    angle = math.radians(bearing)
    dist_x, dist_y = (distance * math.sin(angle), distance * math.cos(angle))
    xfinal, yfinal = (start.x() + dist_x, start.y() + dist_y)
    # resulting point
    return QgsPoint(xfinal, yfinal)

crs = QgsCoordinateReferenceSystem(crsId)
shapetype = QGis.WKBLineString
writer = VectorWriter(output, None, [], shapetype, crs)
start = QgsPoint(centerx,centery)
points =  [mkpoint(start, distance*numrings, b) for b in  xrange(0, 360, degspacing)]
lines = [QgsGeometry.fromPolyline([start, p]) for p in points]

for n in xrange(1, numrings+1):
    buf = QgsGeometry.fromPoint(start).buffer(distance * n, 25)
    lines.append(buf)

for line in lines:
    f = QgsFeature()
    f.setGeometry(line)
    writer.addFeature(f)


del writer