generate method

void generate(double radius)

Implementation

void generate(double radius) {
  if (generators.isEmpty) {
    return;
  }
  _diagram.clear();
  _queue.clear();
  final inverseRadius = 1 / radius;
  final firstGenerator = generators.first;
  _lower.setFrom(firstGenerator.center);
  _upper.setFrom(firstGenerator.center);
  for (final g in generators) {
    Vector2.min(_lower, g.center, _lower);
    Vector2.max(_upper, g.center, _upper);
  }
  _countX = 1 + (inverseRadius * (_upper.x - _lower.x)).toInt();
  _countY = 1 + (inverseRadius * (_upper.y - _lower.y)).toInt();
  for (final g in generators) {
    g.center.setFrom((g.center - _lower)..scale(inverseRadius));
    final x = max(0, min(g.center.x.toInt(), _countX - 1));
    final y = max(0, min(g.center.y.toInt(), _countY - 1));
    _queue.addFirst(VoronoiDiagramTask(x, y, x + y * _countX, g));
  }
  while (_queue.isNotEmpty) {
    final front = _queue.removeFirst();
    final x = front.x;
    final y = front.y;
    final i = front.i;
    final g = front.generator;
    if (_diagram.containsKey(i)) {
      _diagram[i] = g;
      if (x > 0) {
        _queue.addFirst(VoronoiDiagramTask(x - 1, y, i - 1, g));
      }
      if (y > 0) {
        _queue.addFirst(VoronoiDiagramTask(x, y - 1, i - _countX, g));
      }
      if (x < _countX - 1) {
        _queue.addFirst(VoronoiDiagramTask(x + 1, y, i + 1, g));
      }
      if (y < _countY - 1) {
        _queue.addFirst(VoronoiDiagramTask(x, y + 1, i + _countX, g));
      }
    }
  }
  final maxIteration = _countX + _countY;
  for (var iteration = 0; iteration < maxIteration; iteration++) {
    for (var y = 0; y < _countY; y++) {
      for (var x = 0; x < _countX - 1; x++) {
        final i = x + y * _countX;
        final a = _diagram[i]!;
        final b = _diagram[i + 1]!;
        if (a != b) {
          _queue.addFirst(VoronoiDiagramTask(x, y, i, b));
          _queue.addFirst(VoronoiDiagramTask(x + 1, y, i + 1, a));
        }
      }
    }
    for (var y = 0; y < _countY - 1; y++) {
      for (var x = 0; x < _countX; x++) {
        final i = x + y * _countX;
        final a = _diagram[i]!;
        final b = _diagram[i + _countX]!;
        if (a != b) {
          _queue.addFirst(VoronoiDiagramTask(x, y, i, b));
          _queue.addFirst(VoronoiDiagramTask(x, y + 1, i + _countX, a));
        }
      }
    }
    var updated = false;
    while (_queue.isNotEmpty) {
      final front = _queue.removeFirst();
      final x = front.x;
      final y = front.y;
      final i = front.i;
      final k = front.generator;
      final a = _diagram[i]!;
      final b = k;
      if (a != b) {
        final ax = a.center.x - x;
        final ay = a.center.y - y;
        final bx = b.center.x - x;
        final by = b.center.y - y;
        final a2 = ax * ax + ay * ay;
        final b2 = bx * bx + by * by;
        if (a2 > b2) {
          _diagram[i] = b;
          if (x > 0) {
            _queue.addFirst(VoronoiDiagramTask(x - 1, y, i - 1, b));
          }
          if (y > 0) {
            _queue.addFirst(VoronoiDiagramTask(x, y - 1, i - _countX, b));
          }
          if (x < _countX - 1) {
            _queue.addFirst(VoronoiDiagramTask(x + 1, y, i + 1, b));
          }
          if (y < _countY - 1) {
            _queue.addFirst(VoronoiDiagramTask(x, y + 1, i + _countX, b));
          }
          updated = true;
        }
      }
    }
    if (!updated) {
      break;
    }
  }
}