/// <summary> /// /// </summary> /// <param name="searchEnv"></param> /// <param name="start0"></param> /// <param name="end0"></param> /// <param name="mcs"></param> private void ComputeSelect(IEnvelope searchEnv, int start0, int end0, MonotoneChainSelectAction mcs) { ICoordinate p0 = pts[start0]; ICoordinate p1 = pts[end0]; mcs.TempEnv1.Init(p0, p1); // terminating condition for the recursion if (end0 - start0 == 1) { mcs.Select(this, start0); return; } // nothing to do if the envelopes don't overlap if (!searchEnv.Intersects(mcs.TempEnv1)) { return; } // the chains overlap, so split each in half and iterate (binary search) int mid = (start0 + end0) / 2; // Assert: mid != start or end (since we checked above for end - start <= 1) // check terminating conditions before recursing if (start0 < mid) { ComputeSelect(searchEnv, start0, mid, mcs); } if (mid < end0) { ComputeSelect(searchEnv, mid, end0, mcs); } }
/// <summary> /// /// </summary> /// <param name="searchEnv"></param> /// <param name="start0"></param> /// <param name="end0"></param> /// <param name="mcs"></param> private void ComputeSelect(IEnvelope searchEnv, int start0, int end0, MonotoneChainSelectAction mcs) { ICoordinate p0 = pts[start0]; ICoordinate p1 = pts[end0]; mcs.TempEnv1.Init(p0, p1); // terminating condition for the recursion if (end0 - start0 == 1) { mcs.Select(this, start0); return; } // nothing to do if the envelopes don't overlap if (!searchEnv.Intersects(mcs.TempEnv1)) return; // the chains overlap, so split each in half and iterate (binary search) int mid = (start0 + end0) / 2; // Assert: mid != start or end (since we checked above for end - start <= 1) // check terminating conditions before recursing if (start0 < mid) ComputeSelect(searchEnv, start0, mid, mcs); if (mid < end0) ComputeSelect(searchEnv, mid, end0, mcs); }
/// <summary> /// Determine all the line segments in the chain whose envelopes overlap /// the searchEnvelope, and process them. /// </summary> /// <param name="searchEnv"></param> /// <param name="mcs"></param> public void Select(IEnvelope searchEnv, MonotoneChainSelectAction mcs) { ComputeSelect(searchEnv, start, end, mcs); }