scrollWithIndexAndRingcheck static method

void scrollWithIndexAndRingcheck(CoordinateSequence seq, int indexOfFirstCoordinate, bool ensureRing)

Shifts the positions of the coordinates until the coordinate at firstCoordinateIndex is first.

@param seq the coordinate sequence to rearrange @param indexOfFirstCoordinate the index of the coordinate to make first @param ensureRing makes sure that {@code} will be a closed ring upon exit

Implementation

static void scrollWithIndexAndRingcheck(
    CoordinateSequence seq, int indexOfFirstCoordinate, bool ensureRing) {
  int i = indexOfFirstCoordinate;
  if (i <= 0) return;

  // make a copy of the sequence
  CoordinateSequence copy = seq.copy();

  // test if ring, determine last index
  int last = ensureRing ? seq.size() - 1 : seq.size();

  // fill in values
  for (int j = 0; j < last; j++) {
    for (int k = 0; k < seq.getDimension(); k++)
      seq.setOrdinate(
          j, k, copy.getOrdinate((indexOfFirstCoordinate + j) % last, k));
  }

  // Fix the ring (first == last)
  if (ensureRing) {
    for (int k = 0; k < seq.getDimension(); k++)
      seq.setOrdinate(last, k, seq.getOrdinate(0, k));
  }
}