line_segment2.h

/*
 * Copyright (c) 2019, The Regents of the University of California (Regents).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *    1. Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *
 *    3. Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Please contact the author(s) of this library if you have any questions.
 * Authors: David Fridovich-Keil   ( dfk@eecs.berkeley.edu )
 */

///////////////////////////////////////////////////////////////////////////////
//
// Line segment in 2D.
//
///////////////////////////////////////////////////////////////////////////////

#ifndef ILQGAMES_GEOMETRY_LINE_SEGMENT2_H
#define ILQGAMES_GEOMETRY_LINE_SEGMENT2_H

#include <ilqgames/utils/types.h>

#include <glog/logging.h>

namespace ilqgames {

class LineSegment2 {
 public:
  ~LineSegment2() {}
  LineSegment2(const Point2& point1, const Point2& point2)
      : p1_(point1),
        p2_(point2),
        length_((point1 - point2).norm()),
        unit_direction_((point2 - point1) / length_) {
    CHECK_GT(length_, constants::kSmallNumber);
  }

  // Accessors.
  float Length() const { return length_; }
  const Point2& FirstPoint() const { return p1_; }
  const Point2& SecondPoint() const { return p2_; }
  const Point2& UnitDirection() const { return unit_direction_; }
  float Heading() const {
    return std::atan2(UnitDirection().y(), UnitDirection().x());
  }

  // Compute which side of this line segment the query point is on.
  // Returns true for the "right" side and false for the "left.""
  bool Side(const Point2& query) const;

  // Find closest point on this line segment to a given point (and optionally
  // the signed squared distance, where right is positive, and whether or not
  // the closest point is an endpoint).
  Point2 ClosestPoint(const Point2& query, bool* is_endpoint = nullptr,
                      float* signed_squared_distance = nullptr) const;

  EIGEN_MAKE_ALIGNED_OPERATOR_NEW

 private:
  Point2 p1_;
  Point2 p2_;
  float length_;
  Point2 unit_direction_;
};  // struct LineSegment2

}  // namespace ilqgames

#endif