private void buildIndex() { sweepLine = new SweepLineIndex(); for (int i = 0; i < rings.size(); i++) { LinearRing ring = (LinearRing) rings.get(i); Envelope env = ring.getEnvelopeInternal(); SweepLineInterval sweepInt = new SweepLineInterval(env.getMinX(), env.getMaxX(), ring); sweepLine.add(sweepInt); } }