arcball.inl

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/*
    Sheep - A Rigid Body Dynamics Engine
    Copyright (C) 2001-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of Sheep.

    Sheep is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    Sheep is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Sheep; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

inline
Arcball::Arcball() {
    m_q = Quaternion::Identity();
    m_is_dragging = false;
}

inline
void Arcball::BeginDrag(const Vector2 &p) {
    assert(!m_is_dragging);

    m_start_q = m_q;
    m_from = point_on_sphere(p);

    m_is_dragging = true;
}

inline
void Arcball::UpdateDrag(const Vector2 &p) {
    assert(m_is_dragging);

    const Vector3 to = point_on_sphere(p);

    m_q = Quaternion::Rotation(m_from, to) * m_start_q;
    m_q = m_q.Normalized();
}

inline
void Arcball::EndDrag() {
    assert(m_is_dragging);
    m_is_dragging = false;
}

inline
void Arcball::CancelDrag() {
    assert(m_is_dragging);
    m_q = m_start_q;
    m_is_dragging = false;
}

inline
bool Arcball::IsDragging() const {
    return m_is_dragging;
}

inline
void Arcball::SetOrientation(const Quaternion &q) {
    assert(!m_is_dragging);
    m_q = q;
}

inline
const Quaternion &Arcball::GetOrientation() const {
    return m_q;
}

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