import random
from PyQt4.QtCore import QVariant

def checkMinDistance(point, index, distance, points):
    if distance == 0:
        return True
    neighbors = index.nearestNeighbor(point, 1)
    if len(neighbors) == 0:
        return True
    if neighbors[0] in points:
        np = points[neighbors[0]]
        if np.sqrDist(point) < (distance * distance):
            return False
    return True

def generate_wind_turbines(spacing):
    layer = iface.activeLayer()
    crs = layer.crs()
    # Memory layer
    memory_lyr = QgsVectorLayer("Point?crs=epsg:" + unicode(crs.postgisSrid()) + "&index=yes", "Wind turbines for " + str(layer.name()), "memory")
    QgsMapLayerRegistry.instance().addMapLayer(memory_lyr)
    memory_lyr.startEditing()
    provider = memory_lyr.dataProvider()
    provider.addAttributes([QgsField("ID", QVariant.Int)])
    # Variables
    point_density = 0.0001
    fid = 1
    distance_area = QgsDistanceArea()
    # List of features
    fts = []
    # Create points
    for f in layer.getFeatures():
        fGeom = QgsGeometry(f.geometry())
        bbox = fGeom.boundingBox()
        pointCount = int(round(point_density * distance_area.measure(fGeom)))
        index = QgsSpatialIndex()
        points = dict()
        nPoints = 0
        fid += 1
        nIterations = 0
        maxIterations = pointCount * 200
        random.seed()
        while nIterations < maxIterations and nPoints < pointCount:
            rx = bbox.xMinimum() + bbox.width() * random.random()
            ry = bbox.yMinimum() + bbox.height() * random.random()
            pnt = QgsPoint(rx, ry)
            geom = QgsGeometry.fromPoint(pnt)
            if geom.within(fGeom) and checkMinDistance(pnt, index, spacing, points):
                f = QgsFeature(nPoints)
                f.initAttributes(1)
                f.setAttributes([fid])
                f.setGeometry(geom)
                fts.append(f)
                index.insertFeature(f)
                points[nPoints] = pnt
                nPoints += 1
            nIterations += 1
    provider.addFeatures(fts)
    memory_lyr.updateFields()
    memory_lyr.commitChanges()

generate_wind_turbines(500)