```/* <![CDATA[ */
function get_sym_list(){return [["Function","xf",[["mapToSphere",40],["track",15]]]];} /* ]]> */1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
5//
6// This Source Code Form is subject to the terms of the Mozilla
7// Public License v. 2.0. If a copy of the MPL was not distributed
8// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
9
10#include "trackball.h"
11#include "camera.h"
12
13using namespace Eigen;
14
15void Trackball::track(const Vector2i& point2D)
16{
17  if (mpCamera==0)
18    return;
19  Vector3f newPoint3D;
20  bool newPointOk = mapToSphere(point2D, newPoint3D);
21
22  if (mLastPointOk && newPointOk)
23  {
24    Vector3f axis = mLastPoint3D.cross(newPoint3D).normalized();
25    float cos_angle = mLastPoint3D.dot(newPoint3D);
26    if ( internal::abs(cos_angle) < 1.0 )
27    {
28      float angle = 2. * acos(cos_angle);
29      if (mMode==Around)
30        mpCamera->rotateAroundTarget(Quaternionf(AngleAxisf(angle, axis)));
31      else
32        mpCamera->localRotate(Quaternionf(AngleAxisf(-angle, axis)));
33    }
34  }
35
36  mLastPoint3D = newPoint3D;
37  mLastPointOk = newPointOk;
38}
39
40bool Trackball::mapToSphere(const Vector2i& p2, Vector3f& v3)
41{
42  if ((p2.x() >= 0) && (p2.x() <= int(mpCamera->vpWidth())) &&
43      (p2.y() >= 0) && (p2.y() <= int(mpCamera->vpHeight())) )
44  {
45    double x  = (double)(p2.x() - 0.5*mpCamera->vpWidth())  / (double)mpCamera->vpWidth();
46    double y  = (double)(0.5*mpCamera->vpHeight() - p2.y()) / (double)mpCamera->vpHeight();
47    double sinx         = sin(M_PI * x * 0.5);
48    double siny         = sin(M_PI * y * 0.5);
49    double sinx2siny2   = sinx * sinx + siny * siny;
50
51    v3.x() = sinx;
52    v3.y() = siny;
53    v3.z() = sinx2siny2 < 1.0 ? sqrt(1.0 - sinx2siny2) : 0.0;
54
55    return true;
56  }
57  else
58    return false;
59}
60```