/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the demonstration applications of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:LGPL$+
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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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**+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** General Public License version 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL included in the+
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** packaging of this file.  Please review the following information to+
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** ensure the GNU Lesser General Public License version 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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+
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#include "trackball.h"+
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#include "scene.h"+
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+
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//============================================================================//+
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//                                  TrackBall                                 //+
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//============================================================================//+
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+
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TrackBall::TrackBall(TrackMode mode)+
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    : m_angularVelocity(0)+
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    , m_paused(false)+
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    , m_pressed(false)+
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    , m_mode(mode)+
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{+
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    m_axis = QVector3D(0, 1, 0);+
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    m_rotation = QQuaternion();+
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    m_lastTime = QTime::currentTime();+
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}+
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+
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TrackBall::TrackBall(float angularVelocity, const QVector3D& axis, TrackMode mode)+
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    : m_axis(axis)+
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    , m_angularVelocity(angularVelocity)+
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    , m_paused(false)+
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    , m_pressed(false)+
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    , m_mode(mode)+
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{+
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    m_rotation = QQuaternion();+
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    m_lastTime = QTime::currentTime();+
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}+
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+
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void TrackBall::push(const QPointF& p, const QQuaternion &)+
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{+
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    m_rotation = rotation();+
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    m_pressed = true;+
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    m_lastTime = QTime::currentTime();+
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    m_lastPos = p;+
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    m_angularVelocity = 0.0f;+
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}+
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+
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void TrackBall::move(const QPointF& p, const QQuaternion &transformation)+
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{+
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    if (!m_pressed)+
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        return;+
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+
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    QTime currentTime = QTime::currentTime();+
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    int msecs = m_lastTime.msecsTo(currentTime);+
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    if (msecs <= 20)+
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        return;+
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+
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    switch (m_mode) {+
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    case Plane:+
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        {+
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            QLineF delta(m_lastPos, p);+
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            m_angularVelocity = 180*delta.length() / (PI*msecs);+
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            m_axis = QVector3D(-delta.dy(), delta.dx(), 0.0f).normalized();+
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            m_axis = transformation.rotatedVector(m_axis);+
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            m_rotation = QQuaternion::fromAxisAndAngle(m_axis, 180 / PI * delta.length()) * m_rotation;+
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        }+
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        break;+
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    case Sphere:+
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        {+
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            QVector3D lastPos3D = QVector3D(m_lastPos.x(), m_lastPos.y(), 0.0f);+
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            float sqrZ = 1 - QVector3D::dotProduct(lastPos3D, lastPos3D);+
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            if (sqrZ > 0)+
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                lastPos3D.setZ(sqrt(sqrZ));+
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            else+
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                lastPos3D.normalize();+
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+
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            QVector3D currentPos3D = QVector3D(p.x(), p.y(), 0.0f);+
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            sqrZ = 1 - QVector3D::dotProduct(currentPos3D, currentPos3D);+
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            if (sqrZ > 0)+
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                currentPos3D.setZ(sqrt(sqrZ));+
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            else+
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                currentPos3D.normalize();+
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+
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            m_axis = QVector3D::crossProduct(lastPos3D, currentPos3D);+
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            float angle = 180 / PI * asin(sqrt(QVector3D::dotProduct(m_axis, m_axis)));+
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+
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            m_angularVelocity = angle / msecs;+
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            m_axis.normalize();+
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            m_axis = transformation.rotatedVector(m_axis);+
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            m_rotation = QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation;+
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        }+
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        break;+
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    }+
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+
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+
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    m_lastPos = p;+
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    m_lastTime = currentTime;+
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}+
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+
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void TrackBall::release(const QPointF& p, const QQuaternion &transformation)+
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{+
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    // Calling move() caused the rotation to stop if the framerate was too low.+
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    move(p, transformation);+
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    m_pressed = false;+
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}+
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+
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void TrackBall::start()+
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{+
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    m_lastTime = QTime::currentTime();+
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    m_paused = false;+
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}+
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+
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void TrackBall::stop()+
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{+
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    m_rotation = rotation();+
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    m_paused = true;+
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}+
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+
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QQuaternion TrackBall::rotation() const+
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{+
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    if (m_paused || m_pressed)+
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        return m_rotation;+
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+
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    QTime currentTime = QTime::currentTime();+
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    float angle = m_angularVelocity * m_lastTime.msecsTo(currentTime);+
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    return QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation;+
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}+
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+
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