text: /*
   * Copyright (c) 2011-2019, The DART development contributors
   * All rights reserved.
   *
   * The list of contributors can be found at:
   *   https://github.com/dartsim/dart/blob/master/LICENSE
   *
   * This file is provided under the following "BSD-style" License:
   *   Redistribution and use in source and binary forms, with or
   *   without modification, are permitted provided that the following
   *   conditions are met:
   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *   * 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.
   *   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.
   */
  
  #include "dart/gui/Trackball.hpp"
  
  #include "dart/gui/LoadOpengl.hpp"
  #include "dart/math/Constants.hpp"
  
  namespace dart {
  namespace gui {
  
  Trackball::Trackball()
    : mCenter(0.0, 0.0),
      mRadius(1.0),
      mStartPos(0.0, 0.0, 0.0),
      mCurrQuat(1.0, 0.0, 0.0, 0.0)
  {
  }
  
  Trackball::Trackball(const Eigen::Vector2d& _center, double _radius)
    : mCenter(_center),
      mRadius(_radius),
      mStartPos(0.0, 0.0, 0.0),
      mCurrQuat(1.0, 0.0, 0.0, 0.0)
  {
  }
  
  void Trackball::startBall(double _x, double _y)
  {
    mStartPos = mouseOnSphere(_x, _y);
  }
  
  void Trackball::updateBall(double _x, double _y)
  {
    Eigen::Vector3d toPos = mouseOnSphere(_x, _y);
    Eigen::Quaterniond newQuat(quatFromVectors(mStartPos, toPos));
    mStartPos = toPos;
    mCurrQuat = newQuat * mCurrQuat;
  }
  
  void Trackball::applyGLRotation()
  {
    Eigen::Transform<double, 3, Eigen::Affine> t(mCurrQuat);
    glMultMatrixd(t.data());
  }
  
  void Trackball::draw(int _winWidth, int _winHeight)
  {
    const double pi = math::constantsd::pi();
  
    glDisable(GL_LIGHTING);
    glDisable(GL_TEXTURE_2D);
  
    glPushMatrix();
  
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glViewport(0, 0, _winWidth, _winHeight);
    gluOrtho2D(0.0, (GLdouble)_winWidth, 0.0, (GLdouble)_winHeight);
  
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
  
    glLineWidth(4.0);
    glColor3f(1.0f, 1.0f, 0.0f);
    glBegin(GL_LINE_LOOP);
    for (int i = 0; i < 360; i += 4)
    {
      double theta = i / 180.0 * pi;
      double x = mRadius * cos(theta);
      double y = mRadius * sin(theta);
      glVertex2d(
          static_cast<GLdouble>((_winWidth >> 1) + x),
          static_cast<GLdouble>((_winHeight >> 1) + y));
    }
    glEnd();
  
    glPopMatrix();
  }
  
  void Trackball::setTrackball(
      const Eigen::Vector2d& _center, const double _radius)
  {
    mCenter = _center;
    mRadius = _radius;
  }
  
  void Trackball::setCenter(const Eigen::Vector2d& _center)
  {
    mCenter = _center;
  }
  
  void Trackball::setRadius(const double _radius)
  {
    mRadius = _radius;
  }
  
  void Trackball::setQuaternion(const Eigen::Quaterniond& _q)
  {
    mCurrQuat = _q;
  }
  
  Eigen::Quaterniond Trackball::getCurrQuat() const
  {
    return mCurrQuat;
  }
  
  Eigen::Matrix3d Trackball::getRotationMatrix() const
  {
    return mCurrQuat.toRotationMatrix();
  }
  
  Eigen::Vector2d Trackball::getCenter() const
  {
    return mCenter;
  }
  
  double Trackball::getRadius() const
  {
    return mRadius;
  }
  
  Eigen::Vector3d Trackball::mouseOnSphere(double _mouseX, double _mouseY) const
  {
    double mag;
    Eigen::Vector3d pointOnSphere;
  
    pointOnSphere(0) = (_mouseX - mCenter(0)) / mRadius;
    pointOnSphere(1) = (_mouseY - mCenter(1)) / mRadius;
  
    mag = pointOnSphere(0) * pointOnSphere(0)
          + pointOnSphere(1) * pointOnSphere(1);
    if (mag > 1.0)
    {
      double scale = 1.0 / sqrt(mag);
      pointOnSphere(0) *= scale;
      pointOnSphere(1) *= scale;
      pointOnSphere(2) = 0.0;
    }
    else
    {
      pointOnSphere(2) = sqrt(1 - mag);
    }
  
    return pointOnSphere;
  }
  
  Eigen::Quaterniond Trackball::quatFromVectors(
      const Eigen::Vector3d& _from, const Eigen::Vector3d& _to) const
  {
    Eigen::Quaterniond quat;
    quat.x() = _from(1) * _to(2) - _from(2) * _to(1);
    quat.y() = _from(2) * _to(0) - _from(0) * _to(2);
    quat.z() = _from(0) * _to(1) - _from(1) * _to(0);
    quat.w() = _from(0) * _to(0) + _from(1) * _to(1) + _from(2) * _to(2);
    return quat;
  }
  
  } // namespace gui
  } // namespace dart
  