nearestPoint method

@override Vector2 nearestPoint(Vector2 point)

Returns a point on the shape's boundary which is closest to the given point.

The point must lie outside of the shape. If there are multiple nearest points, any one can be returned.

This method will not modify point. At the same time, the caller does not get ownership of the returned object: they must treat it as an immutable short-lived object.

Implementation

@override
Vector2 nearestPoint(Vector2 point) {
  var shortestDistance2 = double.infinity;
  for (var i = 0; i < _vertices.length; i++) {
    final vertex = _vertices[i];
    final edge = _edges[i];
    final dotProduct =
        (point.x - vertex.x) * edge.x + (point.y - vertex.y) * edge.y;
    final t = (dotProduct / edge.length2).clamp(-1.0, 0.0);
    final edgePointX = vertex.x + edge.x * t;
    final edgePointY = vertex.y + edge.y * t;
    final dx = edgePointX - point.x;
    final dy = edgePointY - point.y;
    final distance2 = dx * dx + dy * dy;
    if (distance2 < shortestDistance2) {
      shortestDistance2 = distance2;
      _tmpResult.setValues(edgePointX, edgePointY);
    }
  }
  return _tmpResult;
}