Method nearest_pt_on_line

deps/tesseract/ccstruct/points.cpp:136–145

Returns the point on the given line nearest to this, ie the point such that the vector point->this is perpendicular to the line. The line is defined as a line_point and a dir_vector for its direction.

// that the vector point->this is perpendicular to the line.
// The line is defined as a line_point and a dir_vector for its direction.
FCOORD FCOORD::nearest_pt_on_line(const FCOORD& line_point,
                                  const FCOORD& dir_vector) const {
  FCOORD point_vector(*this - line_point);
  // The dot product (%) is |dir_vector||point_vector|cos theta, so dividing by
  // the square of the length of dir_vector gives us the fraction of dir_vector
  // to add to line1 to get the appropriate point, so
  // result = line1 + lambda dir_vector.
  double lambda = point_vector % dir_vector / dir_vector.sqlength();
  return line_point + (dir_vector * lambda);
}